|
Search of All Forums Enter your search criteria. Click here for tips on using our search |
For Sale Ads |
1: Tubes Asylum, Microphonics (0.00)
Posted by Eli Duttman on 2021-09-14, 11:57:17 (69.142.46.247)
As it was intended for mobile service, the Loktal 7F7 is less prone to vibration sensitivity. The rigid individual pins of Loktal types through the glass base is a plus over the common central stem fo .......
2: Tubes Asylum, RE: 6SL7 Tube Recommendations for Aretha Preamp (0.00)
Posted by Eli Duttman on 2021-09-14, 02:31:47 (69.142.46.247)
Octal 6SL7 is very close to 9 pin mini 5751. μ = 70. Good OS 6SL7s are NOT easy to come by. The RCA tubes you have easily could be outstanding. A possibility is building/buying Loktal to Octal ad .......
3: Vintage Asylum, RE: sorry, I meant to say which manufacturer(s) consistently offered (0.00)
Posted by Eli Duttman on 2021-09-09, 13:02:05 (69.142.46.247)
Years ago, I had a Sansui 7070 receiver and got good service out of it. That series of Sansui receivers were made with wire wrap and need a going over that includes LOTS of soldering, if they are to b .......
4: Vintage Asylum, RE: sorry, I meant to say which manufacturer(s) consistently offered (0.00)
Posted by Eli Duttman on 2021-09-09, 06:48:16 (69.142.46.247)
Pioneer and Sansui consistently get "good press". .......
5: Tubes Asylum, RE: Isn't there another indirectly heated 5y3? nt (0.00)
Posted by Eli Duttman on 2021-08-30, 06:22:50 (69.142.46.247)
Yes, 6087/5Y3WGTB. .......
6: Vintage Asylum, RE: Recommend some new RCA cables for my Philips 312! (0.00)
Posted by Eli Duttman on 2021-08-13, 10:15:15 (69.142.46.247)
You retain the separate motor grounding wire. The sophisticated arrangement uses the 2 conductors for the signal and a "drain" wire from the shield to the phono preamp's grounding post. Do not connect .......
7: Vintage Asylum, RE: Recommend some new RCA cables for my Philips 312! (0.00)
Posted by Eli Duttman on 2021-08-12, 12:56:16 (69.142.46.247)
You want control over the total amount of capacitance the cartridge sees. Low capacitance per foot in the bulk cable you make the interconnects out of is desirable. Additional capacitance, should it b .......
8: Tube DIY Asylum, RE: How does it sound/perform? (0.00)
Posted by Eli Duttman on 2021-08-12, 05:19:45 (69.142.46.247)
The distortion numbers in the thread suggest relatively mild euphonic voicing. The 2A3 is more linear than the 300B, which (IMO) is an effects machine. Pay attention to Lynn Olsen's PP 300B amps, that .......
9: Tubes Asylum, Opamp plus tube buffer = marketing BALONEY. :~(( [nt] (0.00)
Posted by Eli Duttman on 2021-08-08, 15:36:35 (69.142.46.247)
.......
10: Tubes Asylum, RE: "the only opinion that matters is mine! ;)D" (0.00)
Posted by Eli Duttman on 2021-08-07, 21:04:50 (69.142.46.247)
"As for the hybrid designs, having never heard one, I can't comment on the sonics, which may be quite good for the money spent." The tweaked RCA setup I'm associated with is a hybrid. However, all vo .......
11: Tubes Asylum, RE: Apparently Inmate Interstage Tranny doesn't agree (0.00)
Posted by Eli Duttman on 2021-08-06, 19:37:33 (69.142.46.247)
Opinions,everybody has them. However, the only opinion that matters is mine! ;>D Like all "simple" 'X7 setups, the "Chrome Cutie" can't fight its way out of a wet paper bag. The debate of active vs. p .......
12: Tube DIY Asylum, RE: Thanks, any suggestions (0.00)
Posted by Eli Duttman on 2021-08-05, 22:33:33 (69.142.46.247)
Michael Percy shows 100 WVDC 1 μF. MultiCap RTX (polystyrene) parts for $20.25 each. Only PTFE (teflon) is more transparent than polystyrene and PTFE might never run in at low voltages. For the 1 .......
13: Tube DIY Asylum, RE: Low voltage signal path cap recommendation (0.00)
Posted by Eli Duttman on 2021-08-05, 17:13:28 (69.142.46.247)
JMO, low voltage plus low temperature => polystyrene dielectric. .......
14: Tubes Asylum, RE: Good, Reliable, affordable 6922's? (0.00)
Posted by Eli Duttman on 2021-07-29, 16:06:16 (69.142.46.247)
Opinions, everybody has them. I stand by what I said; the 6H23Π is mediocre and the 6H23Π-EB is pretty darned good. Among Russian types, that specimens with the -EB suffix are superior is co .......
15: Tubes Asylum, RE: Good, Reliable, affordable 6922's? (0.00)
Posted by Eli Duttman on 2021-07-29, 14:17:53 (69.142.46.247)
The 6H23Π (6n23p) is so/so. The 6H23Π-EB (6n23p-ev) is very tough and has good, if not great, sonics. The tube New Sensor markets as the ElectroHarmonix (EH) 6922 is, in fact, 6H23Π-EB. .......
16: Vintage Asylum, RE: What cart are you using with your Philips 212/312? (0.00)
Posted by Eli Duttman on 2021-07-28, 20:08:13 (69.142.46.247)
It's a shame that the AT-331LP is no longer in the inventory. :>( That model had a line trace stylus for surprisingly little $. I have that cart. on my 2nd TT, a rather mundane BIC 960, and it plays q .......
17: Vintage Asylum, RE: What cart are you using with your Philips 212/312? (0.00)
Posted by Eli Duttman on 2021-07-27, 11:32:51 (69.142.46.247)
Low mass tone arm, you say. Then stay away from Grado carts., which work well in arms of some mass. Google "Grado dance". JMO, buy the best Audio Technica model, other than 1 of the OC9 LOMC carts., f .......
18: Vintage Asylum, RE: What cart are you using with your Philips 212/312? (0.00)
Posted by Eli Duttman on 2021-07-26, 19:39:56 (69.142.46.247)
What sort of motor does the Philips TT use? Grado carts. are nice, but they pick up hum from unshielded AC motors. Audio Technica offers a wide variety of models. If the cost is not budget busting, th .......
19: Tube DIY Asylum, RE: Thoughts on Input resistor? (0.00)
Posted by Eli Duttman on 2021-07-25, 08:06:23 (69.142.46.247)
2.2 Megohms is a "classic" value, when grid leak, AKA contact, bias is employed. An excellent reason for bringing the grid to ground resistance down in cathode biased designs is avoidance of HF info. .......
20: Tube DIY Asylum, RE: Dynaco C354 Choke Measured Value (0.00)
Posted by Eli Duttman on 2021-07-18, 10:05:25 (69.142.46.247)
Unfortunately, many an original C-354 has failed, leaving a puddle of wax as said failure's "signature". Hopefully, the Triode Electronics replacement parts are manufactured to a higher standard than .......
21: Tube DIY Asylum, RE: An Afterthought... (0.00)
Posted by Eli Duttman on 2021-06-02, 14:43:02 (69.142.46.247)
Take all claims with copious amounts of salt. Still, I have vague memories of high quality laminations (GOSS?) being mentioned. .......
22: Tube DIY Asylum, RE: Volume pot recommendation (0.00)
Posted by Eli Duttman on 2021-05-28, 18:34:07 (69.142.46.247)
Penny and Giles controls are very nice, but they are OUTRAGEOUSLY EXPENSIVE . In a non-motorized part, you will (IMO) do best with something in the KKA series from PEC of Canada . The PEC parts are .......
23: Vintage Asylum, RE: Reduce Vintage Aux Input Sensitivity (0.00)
Posted by Eli Duttman on 2021-05-20, 08:47:38 (69.142.46.247)
Stop making yourself "nucking futz". Commercial CDPs must be capable of driving the 10 Kohm IHF "standard" load. The 100 Kohm I/P impedance of the "vintage" AUX I/P is good enough at satisfying the 1: .......
24: Tube DIY Asylum, RE: "DR low mu design" (0.00)
Posted by Eli Duttman on 2021-05-08, 17:19:26 (69.142.46.247)
T/K, be "nice" to "Professor Snake Oil". ;>D .......
25: Vintage Asylum, RE: Just wait it out a year or two then... (0.00)
Posted by Eli Duttman on 2021-05-08, 17:10:26 (69.142.46.247)
Aside from retiree financial considerations, I've got a McShaned H/K Cit. 2 and a 250 WPC AVA FET valve. "Snake oil" peddling sales people can stay away from my front door. .......
26: Vintage Asylum, RE: So... how do you feel about the PWM ("Class D") amp modules, then? (0.00)
Posted by Eli Duttman on 2021-05-08, 12:51:33 (69.142.46.247)
FWIW, I'm suspicious about a "rave" review associated with an item whose price is high. My mind starts thinking "Emperor's New Clothes". Having not bothered with the equipment in question, I can't off .......
27: Vintage Asylum, RE: Vintage vs New Amplification (0.00)
Posted by Eli Duttman on 2021-05-08, 04:33:02 (69.142.46.247)
The power ICs in today's SS equipment are ghastly. .......
28: Vintage Asylum, RE: Many recordings from that era are still considered unsurpassed. (0.00)
Posted by Eli Duttman on 2021-05-08, 04:30:21 (69.142.46.247)
The revered RCA and Mercury recordings were laid down with Ampex tape recorders that used vacuum tubes. .......
29: Tube DIY Asylum, RE: Check this out - Tube VFD on a 1959 Lathe. (0.00)
Posted by Eli Duttman on 2021-05-06, 10:24:00 (69.142.46.247)
Monarch makes superb machines. Lots of WW2 "vintage" Monarch lathes are still getting things done. .......
30: Tube DIY Asylum, Increasing Gain in Respectable Transconductance 7 Pin Mini Types (0.00)
Posted by Eli Duttman on 2021-05-04, 02:12:57 (69.142.46.247)
6AB4 (1/2 a 'T7) μ = 60 and 6GK5 μ =78. .......
31: Tube DIY Asylum, RE: Cathodyne VS LTP (0.00)
Posted by Eli Duttman on 2021-05-01, 23:35:54 (69.142.46.247)
"Sand" could easily be best for the constant current sink (CCS), say the 10M45S integrated circuit. If 100% "hollow state" is desired, a multi-grid type whose current handling capability is appropriat .......
32: Tube DIY Asylum, RE: Cathodyne VS LTP (0.00)
Posted by Eli Duttman on 2021-05-01, 16:28:47 (69.142.46.247)
JMO, use 6J6 specimens whose sections are reasonably well balanced and force symmetry between the sides with a tail CCS. Given its μ of 38, approx. 20 dB. of stage gain should be realized from a .......
33: Tube DIY Asylum, RE: Diode Tweak (0.00)
Posted by Eli Duttman on 2021-04-28, 19:24:09 (69.142.46.247)
I prefer the UF4007 over the 1N4007, as it produces LESS switching noise. Both parts are rated 1 A./1 KV. How noisy the "sand" is in this application may not matter, as the vacuum rectifier blocks the .......
34: Tube DIY Asylum, RE: Pet peeve (0.00)
Posted by Eli Duttman on 2021-04-26, 14:01:00 (69.142.46.247)
"He goes on to say 'During playback the exact inverse filter characteristic must be applied to receive a flat frequency response'" The quoted remark is inaccurate. Not only must the mastering time HF .......
35: Tube DIY Asylum, RE: Design recommendation d needed. (0.00)
Posted by Eli Duttman on 2021-04-12, 00:13:28 (69.142.46.247)
The OEM power transformer has a 2 A. 5 VAC winding, for the 5Y3. Switching to a 5AR4 increases the B+ rail voltage and allows for a larger valued 1st filter capacitor, without increasing the demand on .......
36: Tubes Asylum, RE: Rectifier differences (0.00)
Posted by Eli Duttman on 2021-04-05, 16:16:56 (69.142.46.247)
Forward drop in 5AR4s is than that in 5U4s. So, you are getting a few more B+ volts. .......
37: Tubes Asylum, RE: Rectifer Tube Choice for easy on the other components............. (0.00)
Posted by Eli Duttman on 2021-04-02, 16:59:24 (69.142.46.247)
The forward drop in 5Y3s is larger than that in 5U4s. Therefore, rectifying with a 5Y3 gets you fewer B+ volts than rectifying with a 5U4. What sort of an effect the "shorter" B+ rail has will be situ .......
38: Tubes Asylum, RE: Rectifer Tube Choice for easy on the other components............. (0.00)
Posted by Eli Duttman on 2021-04-02, 14:40:18 (69.142.46.247)
A 5Y3 yields a "shorter" B+ rail than a 5U4. Good, bad, or indifferent will depend on the specific situation. .......
39: Tubes Asylum, RE: If you like a 5Y3... (0.00)
Posted by Eli Duttman on 2021-04-02, 06:34:03 (69.142.46.247)
Yes, the 6087/5Y3WGTB is nice. I've used 'em. .......
40: Tubes Asylum, RE: Rectifer Tube Choice for easy on the other components............. (0.00)
Posted by Eli Duttman on 2021-04-01, 19:26:10 (69.142.46.247)
Forward drop in 5Y3s is large. You may be hearing the reduction in B+ rail voltage. If, as the schematic suggests, you're taking the "raw" B+ from pin 8 of the rectifier socket, try a Bendix/Red Bank .......
41: Tube DIY Asylum, RE: PEM Nuts (0.00)
Posted by Eli Duttman on 2021-03-28, 16:46:34 (69.142.46.247)
Humor aside, quenching W1 in body temperature urine would reduce cracking risk and might trigger some nitride case hardening. Piss as a quenching agent is definitely out in a "normal" place of busines .......
42: Tube DIY Asylum, RE: PEM Nuts (0.00)
Posted by Eli Duttman on 2021-03-28, 12:37:46 (69.142.46.247)
What, no W1 and fresh piss? :>D .......
43: Tubes Asylum, RE: Tube amp repair in mid-Atlantic? (0.00)
Posted by Eli Duttman on 2021-03-28, 07:21:41 (69.142.46.247)
Try to get in contact with the fellow who posts as wiseoldtech over on DIY Audio. He's in "Philly" .......
44: Tube DIY Asylum, RE: 7-Pin Miniatures (0.00)
Posted by Eli Duttman on 2021-03-23, 16:59:12 (69.142.46.247)
"Poindexter" used the 6005, which is the industrial version of the 6AQ5, in a small signal role. .......
45: Tube DIY Asylum, RE: VR Tubes for Screens (0.00)
Posted by Eli Duttman on 2021-03-23, 10:13:18 (69.142.46.247)
FWIW, I'd use separate stacks for stereo 6L6s. The current limit of VR tubes has me worried. I am not knowledgeable about the sophisticated considerations you mentioned. .......
46: Tube DIY Asylum, RE: VR Tubes for Screens (0.00)
Posted by Eli Duttman on 2021-03-23, 02:31:40 (69.142.46.247)
A 0.068 μF. cap. in parallel with the gas discharge tube stack suppresses the "whoosh". .......
47: Tube DIY Asylum, RE: Shielded Wire (0.00)
Posted by Eli Duttman on 2021-03-22, 07:17:32 (69.142.46.247)
A quite (IMO) reasonable alternative to PTFE insulated wire is the silver plated copper wire wrap stuff, like this from Jonard Industries. While Kynar (PVDF) is not as heat resistant as PTFE, it's sti .......
48: Tube DIY Asylum, RE: Shielded Wire (0.00)
Posted by Eli Duttman on 2021-03-22, 03:12:59 (69.142.46.247)
Soldering stainless steel is anything but easy. :>( McMaster-Carr has tinned copper shield braid , which is exactly what you need. .......
49: Tube DIY Asylum, RE: Shielded Wire (0.00)
Posted by Eli Duttman on 2021-03-21, 12:15:18 (69.142.46.247)
I have not used Mogami W2330. Mogami offers more than 1 cable with a single signal conductor plus wrap shield. Pick the version that offers enough mass to make you comfortable. .......
50: Tube DIY Asylum, RE: Shielded Wire (0.00)
Posted by Eli Duttman on 2021-03-21, 10:53:45 (69.142.46.247)
Multiple colors I don't know about, but black jacket is definitely available. Look here . .......
51: Tubes Asylum, RE: Current 12AX7 Tubes Recs Needed (0.00)
Posted by Eli Duttman on 2021-03-20, 06:55:31 (69.142.46.247)
Which variant you wind up using may depend on the duty the "bottle" is given. Talk to AA sponsor Jim McShane and discuss your needs with him. It is entirely possible you end up with different variants .......
52: Vintage Asylum, RE: Male RCA connector,single pole? (0.00)
Posted by Eli Duttman on 2021-03-18, 17:03:26 (69.142.46.247)
This is what you're looking for. It's used with a "simple" braided shield cable. The braid gets soldered to the "collar". .......
53: Tube DIY Asylum, RE: Is that the right number? (0.00)
Posted by Eli Duttman on 2021-03-16, 10:27:35 (69.142.46.247)
I believe the 6H6Π (6n6p) will do too, especially for "concertina" phase splitter duty. The 6H30Π-ДP (6n30p-dr) is definitely pricey, but lesser grade stock is offered by New Sensor. J .......
54: Tube DIY Asylum, Re: 5687 ? (0.00)
Posted by Eli Duttman on 2021-03-16, 06:39:06 (69.142.46.247)
Reduce the single bottle crosstalk exposure with the Russian 6H30Π (6n30p). The type pins out like a 6922 and the triodes strongly resemble those in the 5687. .......
55: Tube DIY Asylum, RE: 7199 VS 6AN8 (0.00)
Posted by Eli Duttman on 2021-03-16, 01:38:07 (69.142.46.247)
Any of the 6BL8/6GH8/6U8 bunch will work for you. You can also copy what Triode Electronics did in creating replacement driver boards for the Dyna ST-70 and use 2X EF86s plus a twin triode. TE allows .......
56: Vintage Asylum, RE: Different taps on old amp (0.00)
Posted by Eli Duttman on 2021-03-03, 22:56:33 (69.142.46.247)
What does the impedance curve of the speakers look like, particularly in the deep bass. Dips are a warning to take the nominal impedance with copious amounts of salt, when connecting to tube amps. IMO .......
57: Tubes Asylum, RE: Best new tube for ARC Classic 150? (0.00)
Posted by Eli Duttman on 2021-03-01, 16:49:44 (73.215.166.241)
Stick with the New Sensor's "reissue" Gold Lion KT88s. .......
58: Tubes Asylum, RE: Valve preamplifier biasing (0.00)
Posted by Eli Duttman on 2021-02-26, 19:18:27 (73.215.166.241)
Some folks say F 3 needs be a decade (2 Hz.) away from the passband, while other people think 2 octaves (5 Hz.) away is OK. That makes the absolute minimum value for working into that blasted IHF "sta .......
59: Tubes Asylum, RE: Valve preamplifier biasing (0.00)
Posted by Eli Duttman on 2021-02-25, 20:19:23 (73.215.166.241)
I suspect you are dealing with hum balance pots., not bias trim controls. Self, as opposed to fixed", bias is what's commonly encountered in 300B circuitry. .......
60: Tube DIY Asylum, RE: "Grid Leak Resistor" (0.00)
Posted by Eli Duttman on 2021-02-21, 02:37:40 (73.215.166.241)
FWIW, I use the unambiguous grid to ground resistor verbiage. Grid leak, AKA contact, bias can work well in low signal level situations. Given the common cathode connection in 6SC7s, the technique is .......
61: Tube DIY Asylum, RE: Source Follower vs Cathode Follower (0.00)
Posted by Eli Duttman on 2021-02-13, 12:10:35 (73.215.166.241)
Definitely no SS for straight forward voltage amplification. OTOH, quite a few folks find MOSFET source followers to be highly transparent. While the "page" is old, MOSFET Follies remains a good read. .......
62: Vintage Asylum, Useful Links for Adapter Configuring (0.00)
Posted by Eli Duttman on 2021-02-09, 22:41:42 (73.215.166.241)
Look here and here . .......
63: Vintage Asylum, RE: understanding the DIN tape input on a quad 34, original version (0.00)
Posted by Eli Duttman on 2021-02-09, 15:21:59 (73.215.166.241)
That is true. Fortunately, this is a tape monitor loop situation and the recording device (whatever it might be in today's environment) can have its record/play levels adjusted accordingly. ::: TOPIC: .......
64: Tube DIY Asylum, RE: Lower noise metal film resistor than Vishay RN/CMF? (other than bulk foil) (0.00)
Posted by Eli Duttman on 2021-02-08, 02:20:53 (73.215.166.241)
Physically large and costly are Caddock TF020 parts. They are said to compete performance wise with bulk metal foil and may save a few coins. Michael Percy is a source. You said LOMC cartridge "head" .......
65: Tube DIY Asylum, RE: Lower noise metal film resistor than Vishay RN/CMF? (other than bulk foil) (0.00)
Posted by Eli Duttman on 2021-02-07, 23:29:07 (73.215.166.241)
Vishay/Dale RNnn resistors are milspec. They, most definitely, are excellent. Sometimes, you get RN parts, when you order CMF. However, you can't count on that stroke of good fortune. I think CMF coul .......
66: Vintage Asylum, RE: understanding the DIN tape input on a quad 34, original version (0.00)
Posted by Eli Duttman on 2021-02-06, 19:13:51 (73.215.166.241)
You worked it out. It's a single connector tape monitor loop. .......
67: Tube DIY Asylum, RE: A caution (0.00)
Posted by Eli Duttman on 2021-02-05, 06:33:04 (73.215.166.241)
Yes sir, "standing" DC on power trafos is not good. Where that sort of bipolar PSU could work well is at low voltage in combination with opamp ICs. A hefty "12" VAC winding, 2X Schottky diodes, 2X big .......
68: Tube DIY Asylum, RE: I'm trying to understand the terminaology (0.00)
Posted by Eli Duttman on 2021-02-04, 13:11:25 (73.215.166.241)
The "floating" primary side is obviously differential. No grounding, whatsoever, is present The secondary side is differential too, but on the verge of being balanced. Distinguish between signal groun .......
69: Tube DIY Asylum, RE: I'm trying to understand the terminaology (0.00)
Posted by Eli Duttman on 2021-02-04, 12:45:59 (73.215.166.241)
Just about everything is differential. We make things single ended by arbitrarily grounding some point. Take the "full wave" voltage doubler I so frequently fall back on. For a commonplace B+ PSU, the .......
70: Tube DIY Asylum, RE: Phono input wiring (0.00)
Posted by Eli Duttman on 2021-02-03, 19:24:37 (73.215.166.241)
Are the I/P RCA jacks fully insulated from the chassis? If so, connect the shield drain wire to the turntable grounding post. Use the cable's wires to bring the signal (both "hot" and "cold") to the a .......
71: Tubes Asylum, RE: Jim McShane (0.00)
Posted by Eli Duttman on 2021-02-03, 06:42:55 (73.215.166.241)
Retired. .......
72: Tubes Asylum, RE: Jim McShane (0.00)
Posted by Eli Duttman on 2021-02-02, 09:46:06 (73.215.166.241)
Jim, from personal experience, I can definitely confirm getting old SUCKS . However, the alternative is far, far, worse. .......
73: Tube DIY Asylum, RE: Strange tube amp, questions (0.00)
Posted by Eli Duttman on 2021-01-25, 06:50:35 (73.215.166.241)
The safety warnings other posters have issued are spot on! You isolate the electronics from the AC mains with this modestly priced item . Selenium rectifiers are ticking, toxic, time bombs. Replace a .......
74: Vintage Asylum, RE: Scott 99D iron: What to build now? (0.00)
Posted by Eli Duttman on 2021-01-17, 19:40:10 (73.215.166.241)
I suggest you start a new thread for the monoblock pair project on the Tube DIY "board" and link back to this thread. As for scaling back the H/K Cit. 5, that's pretty straight forward. The Cit. 5 use .......
75: Tube DIY Asylum, RE: Would you install a N.O.S. multi-section can cap (over 10 yrs. old/ (0.00)
Posted by Eli Duttman on 2021-01-14, 22:15:36 (73.215.166.241)
Tre' gave you a plan of action. The $64 question is whether or not individual seals have held. Reform and test each individual section. High ESR readings indicate drying out has occurred. .......
76: Tubes Asylum, RE: What do we actually need a preamp for these days...? (0.00)
Posted by Eli Duttman on 2021-01-08, 12:08:51 (73.215.166.241)
Andy, "Unity gain" is (IMO) the key, when only digital sources are a factor. The control center can be either buffered or passive. While passive control centers can work well, they are inflexible. Sh .......
77: Tube DIY Asylum, RE: Help me out... (0.00)
Posted by Eli Duttman on 2021-01-05, 06:56:03 (73.215.166.241)
This transforner should comfortably form the foundation on which a PSU for your field coil drivers would be built. You need 2 transformers for 2 PSUs. 4X UF5408 diodes/PSU take care of bridge rectify .......
78: Tube DIY Asylum, RE: According to the 5AR4 data sheet... (0.00)
Posted by Eli Duttman on 2021-01-04, 10:22:40 (73.215.166.241)
Pin 1 is the connection for a metal ring on the base, when such a ring is present. That's nicely illustrated here . .......
79: Tube DIY Asylum, RE: "5AR4 is "half indirectly" heated" (0.00)
Posted by Eli Duttman on 2021-01-03, 05:19:59 (73.215.166.241)
The terminology is NOT original to me, but I don't immediately recall where I came across it. .......
80: Tube DIY Asylum, RE: "5AR4 is "half indirectly" heated" (0.00)
Posted by Eli Duttman on 2021-01-02, 10:42:43 (73.215.166.241)
Half indirectly heated means the cathode sleeve is tied to 1 end of the heater. An advantage of that construction style is the elimination of heater to cathode potential limit worries. A disadvantage .......
81: Tube DIY Asylum, RE: 5AR4 to 65U4GB (0.00)
Posted by Eli Duttman on 2021-01-02, 08:11:42 (73.215.166.241)
The short answer is no. The 5U4 draws 3 A. of filament current, while the 5AR4 draws 2 A. of heater current. The max. allowable 1st filter cap. size is greater for the 5AR4 than the 5U4. Forward dro .......
82: Vintage Asylum, RE: Would the real 6P3S please stand up (0.00)
Posted by Eli Duttman on 2020-12-28, 06:11:04 (73.215.166.241)
Perhaps a clue lies in the TungSol 5881 datasheet . That document shows the conservative design center value for max. plate dissipation = 23 W. 25 W. would be reasonable for the design maximum number. .......
83: Vintage Asylum, RE: I'm leaning towards harvesting the transformers for DIY monoblocks (0.00)
Posted by Eli Duttman on 2020-12-26, 15:15:48 (73.215.166.241)
Quite a few manufacturers used the "Cheap Charlie" method for DC heaters. FWIW, I loathe it. The thought that the signal might modulate the temperature of preamp tube cathodes makes me cringe. Look cl .......
84: Vintage Asylum, RE: I'm leaning towards harvesting the transformers for DIY monoblocks (0.00)
Posted by Eli Duttman on 2020-12-26, 03:58:24 (73.215.166.241)
If you follow the harvesting path, there are (IMO) 2 obvious candidates for O/P tubes, the 7591 and the 5881 equivalent Russian 6Π3C-E (6p3s-e). The very easy to drive 7591 allows for a 2 stage " .......
85: Vintage Asylum, RE: Volume adjust a pain on two mono amps (0.00)
Posted by Eli Duttman on 2020-12-24, 09:56:04 (73.215.166.241)
The 99-D schematic suggests easily reversed field engineering changes could solve the volume control conundrum. Take advantage of the already present tape monitor loop support. Connect a jack directly .......
86: Tube DIY Asylum, RE: Not Only Banned . . . But Purged (0.00)
Posted by Eli Duttman on 2020-12-21, 20:07:45 (73.215.166.241)
I applaud Klipsch. Excellent handling of a miscreant who constantly peddles "Snake Oil". Shouting fire in a crowded theater, when no fire is present, is (quite correctly) proscribed. Harsh punishment .......
87: Vintage Asylum, RE: Blackie Pagano, Ben Jacoby, or Audio Classics (0.00)
Posted by Eli Duttman on 2020-12-19, 19:13:35 (73.215.166.241)
Bill, is Blackie back in NYC? Some time ago, there were indications he'd relocated to LA. I definitely miss the East Village shows. .......
88: Tube DIY Asylum, RE: SE 6V6 with EF86/6267 driver : anyone build this one? (0.00)
Posted by Eli Duttman on 2020-12-16, 19:15:08 (73.215.166.241)
You can try regulating O/P tube g2 B+ at some fraction of anode B+ and maximize open loop linearity. A complete seat of the pants guess for regulating g2 B+ is a stack of 2X 0B2 gas discharge tubes. : .......
89: Tubes Asylum, RE: Pairing DAC with a Tube AMP (0.00)
Posted by Eli Duttman on 2020-12-16, 02:38:26 (73.215.166.241)
JMO, find a source whose voice is neutral, but not "icy cold". What constitutes excessive euphony is likely highly subjective. However, it IS distortion and loss of fidelity. .......
90: Tube DIY Asylum, RE: Tone - NFB - Gain (0.00)
Posted by Eli Duttman on 2020-12-12, 01:25:08 (73.215.166.241)
"El Cheapo" clearly showed that a 12AT7 LTP had enough gain to fully drive "12" W. types and a NFB loop, when the I/P signal was a "standard" 2 VRMS CDP. Open loop gain will definitely suffer, when wh .......
91: Tube DIY Asylum, RE: Output Tube Choice (Instrument Amp) (0.00)
Posted by Eli Duttman on 2020-12-11, 15:49:18 (73.215.166.241)
I'm not a guitar amp guy. Therefore, take copious amounts of salt along with my remarks. Remember that the EL34 is a true, 3 grid, pentode, while the 'V6 is a beam power tetrode. Leo Fender is reput .......
92: Vintage Asylum, RE: REPLACING CAPS AND PLUG ON CROWN SL2 PREAMP (0.00)
Posted by Eli Duttman on 2020-12-11, 04:26:03 (73.215.166.241)
All upper case is SHOUTING. Please stop. The service manual is here . .......
93: Tube DIY Asylum, RE: Had a chance to pick up a MESS of these... (0.00)
Posted by Eli Duttman on 2020-12-09, 16:03:16 (73.215.166.241)
The 7C5 is nice. Pay close attention to g2 limits, as they may be somewhat less than that found in 6V6GTs destined to be abused in guitar amps. A 330 Ω g2 stopper/current limiter right at the soc .......
94: Tube DIY Asylum, RE: Need recommendations for 4 Pin Sockets for 45 Tube ....... (0.00)
Posted by Eli Duttman on 2020-12-09, 15:52:54 (73.215.166.241)
Mr. Becker, I suggest you shop around for this sort of item. Perhaps Belton is manufacturing suitable parts. Mica loaded phenolic conducts less vibration than ceramic. PTFE ("Teflon") is silly expensi .......
95: Tubes Asylum, RE: We serviced a VanAlstine here recently. (0.00)
Posted by Eli Duttman on 2020-12-03, 21:07:30 (73.215.166.241)
Ralph, Before he started offering a replacement driver board for the Dyna ST-70, Frank VA advocated bandwidth limiting the amp. You can find the write up in his "Audio Basics" archive. FWIW, I complet .......
96: Tubes Asylum, RE: Anyone know of a use for 6W6GT Tubes? (0.00)
Posted by Eli Duttman on 2020-11-30, 19:55:48 (73.215.166.241)
Let's look at a data sheet . Not bad at all, with Design Center limits of 300 V. on the plate and 150 V. on g2. Go full pentode and 0A2 regulate g2 B+. As long as you scrupulously adhere to the 10 W. .......
97: Tubes Asylum, RE: It's all in the driver board (0.00)
Posted by Eli Duttman on 2020-11-30, 10:30:32 (73.215.166.241)
"Me, I would be partial to anything nearest the original design." That's precisely why I suggest the Triode Electronics driver board populated with 2X EF86s and an ECC99. Dyna's topology is retained, .......
98: Tube DIY Asylum, RE: Output Transformer for 4 x 6550 (0.00)
Posted by Eli Duttman on 2020-11-29, 04:27:44 (73.215.166.241)
Unfortunately, neither of those candidates is particularly appealing. A single PP pair of KT88s or 6550s is "typically" associated with "iron" whose primary end to end impedance lies in the 3.0 to 3.5 .......
99: Tube DIY Asylum, RE: 30-60 Second Relay ? (0.00)
Posted by Eli Duttman on 2020-11-23, 20:11:51 (73.215.166.241)
The Amperite models with glass envelopes contain heating elements and who knows what's going on in the newer encapsulated models. The heating elements have lengthy, but finite, lives. Pair an Amperite .......
100: Tube DIY Asylum, RE: 30-60 Second Relay ? (0.00)
Posted by Eli Duttman on 2020-11-22, 22:34:21 (73.215.166.241)
Look here . .......
101: Tube DIY Asylum, RE: Sowter SUT 9990 1:20 measurement (0.00)
Posted by Eli Duttman on 2020-11-20, 16:54:38 (73.215.166.241)
Is your LOMC truly "weak"? If I read things correctly, a tiny bit of HF roll off is present. That's not a bad thing, as rising high end O/P is commonplace among MC cartridges. .......
102: Tube DIY Asylum, RE: Don't know if this is helpful... (0.00)
Posted by Eli Duttman on 2020-11-16, 09:28:15 (73.215.166.241)
Carbon composition (CC) resistors are THE type to use as control electrode stoppers, given their non-metallic and non-inductive nature. CC resistors are prone to noise and drift, which makes them unsu .......
103: Tube DIY Asylum, RE: V5 cathode resistor(s)..? (0.00)
Posted by Eli Duttman on 2020-11-13, 08:01:00 (73.215.166.241)
Not sure, ask Pete. .......
104: Tube DIY Asylum, RE: Cathode bias push-pull DHT question... (0.00)
Posted by Eli Duttman on 2020-11-12, 05:57:01 (73.215.166.241)
You should be safe enough, short term. It's a matter of "equalizing" the potential across the electron emitting surface. In indirectly heated types that have cathode sleeves, the emitting surface is .......
105: Tube DIY Asylum, RE: Another 5842 question, grid and cathode (0.00)
Posted by Eli Duttman on 2020-11-11, 12:49:59 (73.215.166.241)
Perhaps, 10M45S CCS loading would have solved the lack of room issue. .......
106: Tube DIY Asylum, RE: Cathode bias push-pull DHT question... (0.00)
Posted by Eli Duttman on 2020-11-11, 12:46:45 (73.215.166.241)
The 2 O/P tube filaments should have the same AC phasing, in order to achieve hum cancellation in the O/P transformer. Follow the original design of 2 resistors that "synthesize" a CT. A single resist .......
107: Tube DIY Asylum, RE: Another 5842 question, grid and cathode (0.00)
Posted by Eli Duttman on 2020-11-08, 19:52:50 (73.215.166.241)
If you can source and afford tantalum nitride resistors for control grid stoppers, by all means use them. "Us plain folks", whose pockets are "shallow", will use carbon composition. Resistors that ar .......
108: Tubes Asylum, RE: Can someone tell me if 7058 tubes will work in my phono stage? (0.00)
Posted by Eli Duttman on 2020-10-31, 10:28:31 (73.215.166.241)
A true 7058 pins out like a 6922, with pin 9 connected to an internal shield. The triodes inside a 7058 are the "same" as those in a 12AX7. Commonplace 12AX7s can be configured to energize the heaters .......
109: Tubes Asylum, RE: 12AT7 substitutes? (0.00)
Posted by Eli Duttman on 2020-10-30, 07:44:36 (73.215.166.241)
Just use 12AT7s! The 12AU7 is non-linear and its electrical parameters are dead wrong. While damage is unlikely, poor performance is all but certain. If the price of OS 'T7s makes you wince, try JJ's .......
110: Vintage Asylum, RE: Fragile means throw with care . . . I once worked for an airline (0.00)
Posted by Eli Duttman on 2020-10-28, 19:25:14 (73.215.166.241)
That's when people are being polite. Far too often, fragile is interpreted as please, "Gorilla Stomp" me. :>(( .......
111: Vintage Asylum, RE: Restoring a Leak Point One Preamp (0.00)
Posted by Eli Duttman on 2020-10-28, 19:22:13 (73.215.166.241)
Deteriorating cloth insulation on wires can be preserved, some of the time. Consolidate the cloth with clear nail lacquer. Then encase the composite with polyolefin heat shrink tubing. The product is .......
112: Tubes Asylum, RE: "Those discs are just cosmetic" (0.00)
Posted by Eli Duttman on 2020-10-26, 22:52:44 (73.215.166.241)
I need to see an accurate, honest, schematic. Frankly, I don't trust the magazine. Of course, the 2nd gain stage is Class "A". All Class "A" means is that the device conducts 100% of the time. That so .......
113: Tubes Asylum, RE: Audio Innovations 500: same mains transformer for 115V and 230V? (0.00)
Posted by Eli Duttman on 2020-10-26, 21:25:45 (73.215.166.241)
The $64 question is are dual primaries that can be connected either in parallel (for "120" VAC) or in series (for "240" VAC) present. I don't know. .......
114: Tubes Asylum, RE: "Those discs are just cosmetic" (0.00)
Posted by Eli Duttman on 2020-10-26, 21:22:49 (73.215.166.241)
It's hard to think of a worse type for buffer duty than the 12AX7. The triodes in that type "can't fight their way out of a wet paper bag". My hunch is triode voltage amplification and SS buffers. FWI .......
115: Tubes Asylum, RE: "Those discs are just cosmetic" (0.00)
Posted by Eli Duttman on 2020-10-26, 21:15:34 (73.215.166.241)
I have no idea if the circuit in question is truly tubed. However, it's easy enough to get the 250 VDC or so needed for B+. Voltage multiply that 18 VAC . The attached 1/2 wave parallel setup would c .......
116: Tubes Asylum, RE: Tube coolers? (0.00)
Posted by Eli Duttman on 2020-10-24, 14:18:46 (73.215.166.241)
If a mildly microphonic tube is encountered, silicone rubber "O" rings, available from McMaster-Carr, mounted on the bottle at the level of the mica wafers can be beneficial. Silicone can take the hea .......
117: Tubes Asylum, RE: I put in an order with Jim McShane a few months ago (0.00)
Posted by Eli Duttman on 2020-10-24, 14:06:13 (73.215.166.241)
Yes, sir! Noise factor is critical in tubes doing phono duty. Pay a reliable dealer his money and get properly culled specimens. .......
118: Tubes Asylum, RE: Sovtek 12AX7LPS (0.00)
Posted by Eli Duttman on 2020-10-23, 19:44:01 (73.215.166.241)
Define better, please. Properly culled specimens of the 'LPS are clean, quiet, and reasonably priced. What's not to like? As 12AX7s run at plate currents in the 900 μA. to 1 mA. range, heat is, .......
119: Tube DIY Asylum, RE: How much current can a 26 tube take? ,,,,Sorry Eli .... (0.00)
Posted by Eli Duttman on 2020-10-23, 19:32:31 (73.215.166.241)
I didn't say it did. However, it's linear . Some folks like euphony and other people like honesty. My preference is for the tiniest hint of euphony. I dislike both "icy cold" and "syrupy". ::: TOPIC .......
120: Tubes Asylum, RE: Tube rolling question on phono preamp (0.00)
Posted by Eli Duttman on 2020-10-23, 19:22:55 (73.215.166.241)
Discuss your needs with AA sponsor Jim McShane. If he has a nice pair of phono grade Sovtek 12AX7LPS tubes in the "stash", look no further. In any event, Jim will fix you up with a nice, quiet, set of .......
121: Tubes Asylum, RE: 6SN7 to 6922 adapter? (0.00)
Posted by Eli Duttman on 2020-10-23, 19:18:30 (73.215.166.241)
Quality OS 6SN7s, even those lightly used, are worth some $. JMO, sell to buy. ;>) .......
122: Tubes Asylum, RE: 6SN7 to 6922 adapter? (0.00)
Posted by Eli Duttman on 2020-10-23, 16:54:43 (73.215.166.241)
Don't do it!! The triodes are VERY different and the 6SN7 draws 2X the heater current. :>(( The affordable, safe, and decent sounding option is the Russian 6H23Π-EB (6n23p-ev). FYI the ElectroH .......
123: Tube DIY Asylum, RE: How much current can a 26 tube take? (0.00)
Posted by Eli Duttman on 2020-10-22, 04:53:37 (73.215.166.241)
THE factor that controls μ is geometry. Change the geometry and it's not a #26 any more. JMO, if you want more gain combined with high linearity, use the triode found in the 6SN7 and several oth .......
124: Tube DIY Asylum, RE: Millet 6B4G amplifier - power supply peculiarity (0.00)
Posted by Eli Duttman on 2020-10-14, 23:34:45 (73.215.166.241)
The power O/P stage is decoupled from the small signal stages and that is adequate. If OCD will not let you rest, add a "check valve" diode, as was done in "El Cheapo". .......
125: Tubes Asylum, RE: What Eli says - get a phono stage! (0.00)
Posted by Eli Duttman on 2020-10-14, 23:22:35 (73.215.166.241)
No personal experience. However, I do know folks who were quite satisfied with earlier versions of Hagerman's Bugle. .......
126: Tubes Asylum, RE: What Eli says - get a phono stage! (0.00)
Posted by Eli Duttman on 2020-10-13, 21:48:34 (73.215.166.241)
Certainly! .......
127: Tubes Asylum, RE: What Eli says - get a phono stage! (0.00)
Posted by Eli Duttman on 2020-10-13, 19:39:09 (73.215.166.241)
FWIW, I previously linked Jim Hagerman's Bugle3 stand alone phono preamp. Jim cleverly used high quality opamp ICs and passive RIAA EQ to get something both good sounding and quite reasonable in cost. .......
128: Tubes Asylum, RE: seeking first tube amplifier advice (0.00)
Posted by Eli Duttman on 2020-10-12, 02:04:31 (73.215.166.241)
1st, get your "vinyl" listening going again, quickly. Jim Hagerman's Bugle3 will, while sounding good, affordably do that for you and it will be synergistic with a tubed "integrated" amp you then acq .......
129: Tubes Asylum, RE: seeking first tube amplifier advice (0.00)
Posted by Eli Duttman on 2020-10-12, 01:45:48 (73.215.166.241)
Also, MANY Carey items badly abuse vacuum rectifiers. :>(( .......
130: Tube DIY Asylum, RE: 6 volt rectifier tubes (0.00)
Posted by Eli Duttman on 2020-10-10, 22:31:37 (73.215.166.241)
Compare the Philips EZ81 datasheet with East German (DDR) RFT EZ81 datasheet . I see no glaring discrepancies. The Philips datasheet suggests some "wiggle room", especially if the value of the 1st fil .......
131: Tube DIY Asylum, RE: 6 volt rectifier tubes (0.00)
Posted by Eli Duttman on 2020-10-10, 21:21:09 (73.215.166.241)
Look closely at the 6BY5 datasheet. That 175 mA. is per diode. If all you need is 150 mA., the 6CA4/EZ81 will do the job for you. That Noval type IS the "little brother" of the 5AR4/GZ34, including t .......
132: Tube DIY Asylum, RE: ????????????? for Eli Duttman (0.00)
Posted by Eli Duttman on 2020-10-10, 21:15:33 (73.215.166.241)
The RCA original's gain is approx. 45 dB. Expect a bit more, with the 2nd gain block being buffered. .......
133: Vintage Asylum, RE: I've got a Heathkit AR-29 and need some parts for MPX board (0.00)
Posted by Eli Duttman on 2020-10-03, 22:02:32 (73.215.166.241)
Sure appears to be mH. sized and adjustable. .......
134: Vintage Asylum, RE: I've got a Heathkit AR-29 and need some parts for MPX board (0.00)
Posted by Eli Duttman on 2020-10-03, 16:15:13 (73.215.166.241)
MCM was owned by the same folks as Newark. For whatever reasons (profit among them), MCM was "folded" into Newark. Go to Parts Express for some of the stuff that used to be sourced from MCM. ::: TOPIC .......
135: Vintage Asylum, RE: I've got a Heathkit AR-29 and need some parts for MPX board (0.00)
Posted by Eli Duttman on 2020-10-03, 13:44:25 (73.215.166.241)
The "arrows" on the inductor symbols indicate adjustable. It seems my guess about μH. was wrong. FWIW, I was thinking RF parts, but those chokes are part of a 15 KHz. low pass filter. Can photos .......
136: Tubes Asylum, RE: Best sounding power pentode/tetrode in triode for SE? (0.00)
Posted by Eli Duttman on 2020-10-03, 04:32:26 (73.215.166.241)
Triode wired 6V6 family tubes are very nice. A remark not original to me is that in this power range, you have to use #45 DHTs to do better. I can tell you from personal experience (DECWARE SE84) that .......
137: Vintage Asylum, RE: I've got a Heathkit AR-29 and need some parts for MPX board (0.00)
Posted by Eli Duttman on 2020-10-02, 22:30:34 (73.215.166.241)
I'm guessing you need micro (μ) henry inductors, not milli (m) henry parts. Look here for parts quite close to the values specified. .......
138: Tube DIY Asylum, RE: Thanks... (0.00)
Posted by Eli Duttman on 2020-09-14, 12:51:25 (73.215.166.241)
There are always exceptions to generalities. The 'Z6, which comes in several heater voltages, was intended for doubler duty, from the very beginning. ;>) I totally agree with avoiding vacuum diodes i .......
139: Tubes Asylum, RE: 6922 to 6SL7 (0.00)
Posted by Eli Duttman on 2020-09-14, 12:26:10 (73.215.166.241)
The 6SL7 exhibits very high plate resistance and very low transconductance. The 6922 exhibits very low plate resistance and very high transconductance. The 2 types are NOT compatible. Definitely lea .......
140: Tube DIY Asylum, RE: Thanks... (0.00)
Posted by Eli Duttman on 2020-09-13, 15:31:17 (73.215.166.241)
What the original motivation was, I can't say. However, 2X of those "puppies" would be fine as the doubler stack in my 117Z6 PSU. Complete the "boutiquifying" with a DC link part in the reservoir posi .......
141: Tube DIY Asylum, RE: Best .22 ufd (450V-650V) coupling cap... (0.00)
Posted by Eli Duttman on 2020-09-09, 14:44:45 (73.215.166.241)
FWIW, I'd eschew PTFE dielectric, when connecting from I/P jack to the initial voltage gain stage. PTFE might never break in, under that set of circumstances. :>( In situations where break in is/can b .......
142: Tube DIY Asylum, RE: Tell me more about that semiconductor (0.00)
Posted by Eli Duttman on 2020-08-13, 15:27:55 (69.142.177.2)
The crucial reverse transfer capacitance is tiny and (apparently) stable. The little FET works like "Gang Busters" in the tweaked RCA phono setup. Even the wimpy 'X7 triode has no problem driving it W .......
143: Tube DIY Asylum, RE: EL-95 amplifier (0.00)
Posted by Eli Duttman on 2020-08-13, 12:45:21 (69.142.177.2)
How about holding the bottle count down even more? SS rectified B+ is a given. A 6H2Π-EB (6n2p-ev) shared between the channels for voltage amplification and DC coupled ZVN0545A "concertina" phase .......
144: Vintage Asylum, RE: Harmon Kardon Citation-II (0.00)
Posted by Eli Duttman on 2020-07-27, 17:41:11 (69.142.177.2)
That's a millennium level deal! $20 for 1 of the very best amps, ever. Yowzuh!! .......
145: Tubes Asylum, RE: Push-Pull Tube Amps for Dummies: Questions 1 & 2 (0.00)
Posted by Eli Duttman on 2020-07-26, 02:57:50 (69.142.177.2)
Various power tube types are rated for differing anode (plate) dissipation. The KT88/6550 group is rated higher than the EL34/KT77 group. So, 4X KT88s will comfortably deliver 100+ W., while 4X EL34s .......
146: Tubes Asylum, RE: tubes that interchange with the CV378? (0.00)
Posted by Eli Duttman on 2020-07-26, 02:17:40 (69.142.177.2)
Direct shopping with New Sensor is a very bad idea. AA sponsor Jim McShane sells thoroughly tested EH 5U4GBs for less than $20 each. Jim also sells NOS GE 5U4GBs for less than $30 each. .......
147: Tubes Asylum, RE: tubes that interchange with the CV378? (0.00)
Posted by Eli Duttman on 2020-07-25, 21:29:08 (69.142.177.2)
If 5U4GBs are working well, I would not bother with rounding GZ37s up. They are out of production and carry HEFTY price tags that will only get worse, over time. OTOH, New Sensor is currently manufact .......
148: Tubes Asylum, RE: tubes that interchange with the CV378? (0.00)
Posted by Eli Duttman on 2020-07-24, 21:48:31 (69.142.177.2)
The 5U4GB is a much safer swap. Forward drop in a 5R4 providing 250 mA. of B+ is a whopping 67 V. :>( Also, the 5R4 is less tolerant of a good sized, if not huge, capacitance in the 1st filter cap. po .......
149: Tubes Asylum, RE: tubes that interchange with the CV378? (0.00)
Posted by Eli Duttman on 2020-07-24, 14:50:53 (69.142.177.2)
Cary has been known to ABUSE vacuum rectifiers with large valued cap. I/P filters. :>( Other than that warning, the 2 types frequently can be interchanged. A proper CLC (Π section) filter with a .......
150: Tubes Asylum, RE: tubes that interchange with the CV378? (0.00)
Posted by Eli Duttman on 2020-07-24, 01:04:20 (69.142.177.2)
IIRC, CV378 = GZ37. The GZ37 has cathode sleeves. The 5U4GB is directly heated (no cathode sleeves). 5 V./3 A. heating is employed by both types. In combination with a choke I/P filter, up to 350 mA. .......
151: Tubes Asylum, RE: Matched Tubes, What does it Actually Mean (0.00)
Posted by Eli Duttman on 2020-07-17, 05:31:29 (69.142.177.2)
You misunderstand me. Amp manufacturers overcharge for replacement tubes. :>( Guys, like McShane, who truly know their business are who you go to for replacement tubes. Competent dealers know what wor .......
152: Tubes Asylum, RE: Matched Tubes, What does it Actually Mean (0.00)
Posted by Eli Duttman on 2020-07-16, 17:20:09 (69.142.177.2)
A reliable dealer labels the cardboard box with the measured values for gm and cathode current. Also, experienced dealers test the tubes under conditions resembling those found in working amps. Factor .......
153: Vintage Asylum, RE: "Magic Eye Tube Vu Meters": Do such devices exist or be made? (0.00)
Posted by Eli Duttman on 2020-07-11, 20:49:18 (69.142.177.2)
Receiving equipment is (IMO) self evident, but even in stereo times, indicator tubes were used in tape equipment. I had a Webcor stereo machine so configured. .......
154: Vintage Asylum, RE: "Magic Eye Tube Vu Meters": Do such devices exist or be made? (0.00)
Posted by Eli Duttman on 2020-07-11, 06:24:12 (69.142.177.2)
Not quite Vu meters, but "magic eyes" were used as level indicators on tape recording devices. .......
155: Tube DIY Asylum, RE: Why nickel? (0.00)
Posted by Eli Duttman on 2020-07-04, 03:36:07 (69.142.177.2)
Gapped may be the key word. Nickel saturates easily. So, "standing" DC is a very bad idea. Save the Ni for "parafeed" and (perhaps) PP situations. IIRC, a few years ago, MagneQuest/Bottlehead sold som .......
156: Vintage Asylum, RE: upgrade dilemma between two turntables! (0.00)
Posted by Eli Duttman on 2020-06-29, 20:15:50 (69.142.177.2)
Toss a coin? Whichever comes 1st, it will be nice. More than $50 less expensive than $300 is this AT item . It will be safe on the Thorens TT. Grado may "sound" better than AT, but Grado is vulnerable .......
157: Tubes Asylum, RE: Looking for NOS only. (0.00)
Posted by Eli Duttman on 2020-06-20, 21:39:56 (69.142.177.2)
If for no reason other than toughness, ARC uses Reflektor (Saratov, Russia) made 6922 "equivalents". You need that toughness and also want good sounding NOS. Hicksville, NY, made Amperex 7308s check a .......
158: Tubes Asylum, RE: Tube preamp for Magnavox EL84pp and Thorens TT (0.00)
Posted by Eli Duttman on 2020-06-18, 03:28:47 (69.142.177.2)
JMO, a "refurbished" Dyna PAS or something similar can easily be "a pig in a poke". Would separate phono and line stages be acceptable? If so, Jim Hagerman's Cornet phono preamp would leave $ for the .......
159: Vintage Asylum, RE: Cleaning that Harman Kardon Copper (0.00)
Posted by Eli Duttman on 2020-06-16, 17:30:08 (69.142.177.2)
Yes, anything remotely abrasive, including toothpaste, is out. Try lemon juice, on the reverse side. The combination of citric and ascorbic acids frequently "cuts" through tarnish to clean metal. ::: .......
160: Tubes Asylum, RE: Will do, those Sovtek 5AR4 were firecrackers (0.00)
Posted by Eli Duttman on 2020-06-12, 02:46:14 (69.142.177.2)
The Sovtek 5AR4 is satisfactory, IF the series SS diode tweak is employed. I prefer UF4007s over the 1N4007s shown in the graphic. The thinking is less SS switching noise, from the outset, can't be ba .......
161: Tubes Asylum, RE: GZ37 modern replacement (0.00)
Posted by Eli Duttman on 2020-06-11, 20:00:43 (69.142.177.2)
A lot of GZ37s were pressed into service as "substitutes" for the GZ34/5AR4. Check with AA sponsor Jim McShane for truly satisfactory current production 5AR4s. It took longer than we would like, but N .......
162: Vintage Asylum, RE: hk930? Go for the gusto! (0.00)
Posted by Eli Duttman on 2020-06-11, 19:56:41 (69.142.177.2)
That's definitely "cute". :>) Mark, do you think something from Edcor's GXE line , as the O/P "iron", would do better than Hammond's "universal" replacement 125E ? .......
163: Vintage Asylum, RE: Make Sure It Endures (0.00)
Posted by Eli Duttman on 2020-06-07, 15:06:17 (69.142.177.2)
The current production 7591 issue is a matter of concern with both units. Your tech can find plenty of posts about the issue and solutions in the AA archives. .......
164: Vintage Asylum, RE: Make Sure It Endures (0.00)
Posted by Eli Duttman on 2020-06-06, 09:39:23 (69.142.177.2)
What KT88s?? The receiver uses 7591 "finals". Fisher used high quality signal caps. that frequently hold up over time. That's a different story than 'lytics, which DO dry out over time. Tuner alignmen .......
165: Vintage Asylum, Make Sure It Endures (0.00)
Posted by Eli Duttman on 2020-06-06, 02:51:42 (69.142.177.2)
A unit that old needs to be serviced by a competent tube technician, even if it's to be kept in something resembling a "bone stock" state. All electrolytic capacitors require replacement, as those pa .......
166: Vintage Asylum, RE: Fisher 800 blues. (0.00)
Posted by Eli Duttman on 2020-06-05, 16:42:52 (69.142.177.2)
I see some things that may help. The phono I/Ps get directly connected to a turntable fitted with a magnetic cartridge, not that external box. If you want to use that external box, it connects to line .......
167: Tube DIY Asylum, RE: SN63 (0.00)
Posted by Eli Duttman on 2020-06-05, 12:07:25 (69.142.177.2)
60/40 is close to eutectic. while 63/37 IS eutectic. Eutectic alloys behave like pure substances and change state (solid/liquid or vice versa) at a single temperature. No cold joints due to a slight t .......
168: Vintage Asylum, RE: Fisher 800 blues. (0.00)
Posted by Eli Duttman on 2020-06-04, 20:32:17 (69.142.177.2)
Tape head is a low level I/P that's connected to the same general circuitry as a magnetic phono cartridge. A different EQ setup that accounts for NAB vs. RIAA gets used. As tape head I/Ps are passe in .......
169: Tube DIY Asylum, RE: SN63 (0.00)
Posted by Eli Duttman on 2020-06-03, 12:49:55 (69.142.177.2)
I agree with Ralph. Get 63/37 Sn/Pb eutectic with RA flux and you'll do fine. Select a wire size you're comfortable with and avoid brand "X". Kester and MultiCore are well proven brands. If and when .......
170: Tube DIY Asylum, RE: 6H30P can be run there (0.00)
Posted by Eli Duttman on 2020-05-27, 22:41:28 (69.142.177.2)
The issue with the 6H30Π (6n30p) is its lowish μ of 15. .......
171: Tube DIY Asylum, RE: Loose Tube sockets 12BY7 on HK Citation 2 (0.00)
Posted by Eli Duttman on 2020-05-27, 21:09:45 (69.142.177.2)
Try a dental pick as the retensioning tool. If that fails, contact Jim McShane for the proper replacement sockets. .......
172: Tube DIY Asylum, RE: Suggestion for a triode, about 20mA, gain about 20? (0.00)
Posted by Eli Duttman on 2020-05-26, 14:40:52 (69.142.177.2)
The OS only 5687 exhibits a μ of approx. 17. The current production ECC99 exhibits a μ of 22 and draws somewhat less heater current than the 5687. .......
173: Tube DIY Asylum, RE: Strike Voltage (0.00)
Posted by Eli Duttman on 2020-05-15, 11:48:55 (69.142.177.2)
Energy from sources other than the electric field reduces the "striking" voltages of gas discharge devices. Other sources include light and radioactive decay. Constructing gas discharge devices with a .......
174: Tube DIY Asylum, RE: Nixie Tube Current? (0.00)
Posted by Eli Duttman on 2020-05-14, 19:47:09 (69.142.177.2)
When push comes to shove, a "Nixie" tube is a NE2 "on steroids". IIRC, neon "strikes" at something like 60 V. Remember, to get glow around both rods of a NE2 it must be energized with AC. DC yields gl .......
175: Vintage Asylum, RE: Belts for Sony SCD-C555ES? (0.00)
Posted by Eli Duttman on 2020-05-13, 13:45:27 (69.142.177.2)
It can't hurt to inquire. EA is a belt specialist. .......
176: Vintage Asylum, RE: Belts for Sony SCD-C555ES? (0.00)
Posted by Eli Duttman on 2020-05-13, 12:55:59 (69.142.177.2)
Elix Atelier? .......
177: Tube DIY Asylum, RE: Quad cap? (0.00)
Posted by Eli Duttman on 2020-05-10, 16:01:53 (69.142.177.2)
When switching a ST70 to SS rectified B+, installation of filter caps. whose WVDC is sufficiently "tall" is essential. An inrush current limiting thermistor is definitely a good idea. FWIW, the extra .......
178: Tube DIY Asylum, RE: PIV? (0.00)
Posted by Eli Duttman on 2020-05-09, 20:12:06 (69.142.177.2)
Yes, PIV = peak inverse voltage. What happens (I think) is the PIV capabilities of the SS diode and vacuum diode are adding together. Regardless of mechanism, the tweak works. I am not the originator .......
179: Tube DIY Asylum, RE: Dynaco dying.... (0.00)
Posted by Eli Duttman on 2020-05-09, 17:07:44 (69.142.177.2)
The weak spot in the Sovtek 5AR4 is meeting the PIV specification. In all other aspects, the variant is satisfactory. The series SS diode tweak provides extra PIV headroom that prevents that wretched .......
180: Tube DIY Asylum, RE: Dynaco dying.... (0.00)
Posted by Eli Duttman on 2020-05-08, 22:31:33 (69.142.177.2)
If you're going to use the Sovtek 5AR4, the series SS diode tweak is a must. While the diagram shows 1N4007s, I prefer UF4007s. Yes, the vacuum rectifier blocks SS diode switching noise from entering .......
181: Tubes Asylum, RE: Phase inverter tube choice question (0.00)
Posted by Eli Duttman on 2020-05-08, 14:19:37 (69.142.177.2)
V1 is a differential gain block phase splitter, AKA long tailed pair (LTP). The theoretical max. gain for such a setup is 1/2 the amplification factor (μ). In practice, roughly 1/4 μ is obta .......
182: Tube DIY Asylum, RE: My rationale for "Shunt" vs "Bleeder" (0.00)
Posted by Eli Duttman on 2020-05-08, 12:31:18 (69.142.177.2)
In the future, we'll have to pay New Sensor's price for Reflektor made 6Π3C-E stock. This is what EBone is currently showing for the Russian 5881s and the $ seem "reasonable". .......
183: Tubes Asylum, RE: Phase inverter tube choice question (0.00)
Posted by Eli Duttman on 2020-05-08, 12:01:51 (69.142.177.2)
The 12AU7 is non-linear and (IMO) is OK only in the cathode follower or "concertina" phase splitter roles. Definitely use 12BH7s in positions where a gain in signal voltage occurs. Don't lose sight of .......
184: Tube DIY Asylum, RE: Refurbing old PA amp, need help with PSU (0.00)
Posted by Eli Duttman on 2020-05-07, 21:44:51 (69.142.177.2)
Yes, that old cloth wire insulation deteriorates. If flexibility is not a significant concern, that cloth can be consolidated with clear nail lacquer and then protected with polyolefin heatshrink tubi .......
185: Tube DIY Asylum, RE: Refurbing old PA amp, need help with PSU (0.00)
Posted by Eli Duttman on 2020-05-07, 20:39:01 (69.142.177.2)
The rectifier is a 5U4 and either of NOS GE or current production ElectroHarmonix (EH) 5U4GB s will be fine. Steer clear of Chinese and Russian ST bottle 5U4 "equivalents", as they are utter trash. A .......
186: Tube DIY Asylum, RE: PSU Question (0.00)
Posted by Eli Duttman on 2020-05-06, 14:07:08 (69.142.177.2)
By all means, leave things be, unless a particular problem is observed. Whatever current passes through the bleeder is wasted and converted into heat. The only reason for using a "modest" value in the .......
187: Tube DIY Asylum, RE: PSU Question (0.00)
Posted by Eli Duttman on 2020-05-06, 09:48:47 (69.142.177.2)
Remember choke I/P filter critical current. That bleeder you described is trivial and only serves to discharge. Frequently, a smaller valued bleeder is placed across the 1st filter cap., to ensure tha .......
188: Tube DIY Asylum, Fixed (sort of) (0.00)
Posted by Eli Duttman on 2020-04-30, 13:59:04 (69.142.177.2)
Steve, The B+ rail will come in wherever current AC mains service puts it, but that's NBD. "Full wave" voltage double the negative rail winding to make darned sure you can completely cut the 7591s off .......
189: Tube DIY Asylum, RE: With no much to do... Fisher 500C (0.00)
Posted by Eli Duttman on 2020-04-30, 10:48:01 (69.142.177.2)
Steve, You are correct about small signal circuitry used with "12" W. types also working with 7591s. A slew of manufacturers, including Fisher, exploited that fact. However, 400+ VDC is needed on the .......
190: Tube DIY Asylum, RE: With no much to do... Fisher 500C (0.00)
Posted by Eli Duttman on 2020-04-29, 22:44:26 (69.142.177.2)
Current production 7591s are intolerant of the liberties Fisher took with the grid to ground resistance limit. IMO, the motive driving that was inventorying "only" 12AX7s. The 'X7 triode makes a poor .......
191: Tubes Asylum, RE: Looking at an EL34 integrated that uses a single output tube per side (0.00)
Posted by Eli Duttman on 2020-04-27, 12:37:40 (69.142.177.2)
3.5-4 W. is (IMO) a reasonable guesstimate. .......
192: Tube DIY Asylum, RE: Any 6U10 users or fans out there? (0.00)
Posted by Eli Duttman on 2020-04-20, 07:15:09 (69.142.177.2)
An (IMO) obvious improvement is loading the LTP tails with 10M45S CCSes, instead of 18 Kohm resistors, and employing identical plate load resistors. A low voltage negative rail might be needed for "co .......
193: Tube DIY Asylum, RE: Any 6U10 users or fans out there? (0.00)
Posted by Eli Duttman on 2020-04-19, 15:41:46 (69.142.177.2)
The 6U10 datasheet suggests 2X 'U7 and 1X 'X7 sections in a single bottle. While I'm definitely anti-'U7, except as a cathode follower or "concertina" phase splitter, relying on NFB to deal with the n .......
194: Tubes Asylum, RE: Do you own a volt meter? (0.00)
Posted by Eli Duttman on 2020-04-11, 03:37:35 (69.142.177.2)
I think the infrasonic filter is more important. Protecting the O/P "iron" from core saturation, due to things like record warps, truly matters. You deal, should the choice to do so be made, with HF i .......
195: Tube DIY Asylum, H/K Cit. 2! (nt) (0.00)
Posted by Eli Duttman on 2020-04-05, 17:43:14 (69.142.177.2)
.......
196: Tube DIY Asylum, RE: Half wave rectifiers used in a bridge config (0.00)
Posted by Eli Duttman on 2020-04-04, 23:34:18 (69.142.177.2)
If you want to spend less on the SS stuff, use snubbed, series wired, pairs (4 diodes total) of 1 A. UF4007s or 3 A. UF5408s (1000 PIV) in the ground legs. The vacuum diodes will keep the small amount .......
197: Tube DIY Asylum, RE: Half wave rectifiers used in a bridge config (0.00)
Posted by Eli Duttman on 2020-04-04, 17:40:41 (69.142.177.2)
For a 220 mA. draw, you'll be FINE using 2X 6CL3s in the "hot" legs of a hybrid bridge. As you said, the type is rated for a 250 mA. draw, in 1/2 wave service, and there are a pair shouldering the loa .......
198: Tube DIY Asylum, RE: Half wave rectifiers used in a bridge config (0.00)
Posted by Eli Duttman on 2020-04-04, 06:13:57 (69.142.177.2)
You solve the doubled forward drop problem by employing a hybrid bridge rectifier. For a B+ rail, 2X SS diodes (preferably high PIV Schottky) in the ground legs and whatever vacuum stuff that tickles .......
199: Vintage Asylum, RE: Console consultation (0.00)
Posted by Eli Duttman on 2020-04-01, 09:55:51 (69.142.177.2)
Those things were usually equipped with a record destroying changer/piezoelectric cart. combo. Replace the TT and install a Hagerman Bugle2 to get a MM cart. up to "line" level. Can you post the schem .......
200: Tubes Asylum, RE: Loktal equivalent of 6V6? (0.00)
Posted by Eli Duttman on 2020-03-08, 08:48:47 (69.142.177.2)
7C5! .......
201: Tube DIY Asylum, RE: "No PTFE here, because it might never run in" (0.00)
Posted by Eli Duttman on 2020-03-02, 08:35:43 (69.142.177.2)
In that circuit, C2 is exposed to "standing" DC. I have no hard proof, but suspect "problem child" dielectrics, like PTFE, require both "standing" DC and AC to run in. Perhaps, dielectric absorption e .......
202: Tube DIY Asylum, RE: Why not Teflon? (0.00)
Posted by Eli Duttman on 2020-03-01, 19:14:45 (69.142.177.2)
No PTFE here, because it might never run in. .......
203: Tube DIY Asylum, RE: Well!!!!!!!!!!! I'm convinced!!!!!!!!!!!!!!! (0.00)
Posted by Eli Duttman on 2020-03-01, 19:12:50 (69.142.177.2)
I prefer polystyrene dielectric, in these positions. Polystyrene is almost as transparent as PTFE, without carrying run in baggage. Usually, little or no DC is found here. PTFE takes a long time to ru .......
204: Tube DIY Asylum, RE: Well!!!!!!!!!!! I'm convinced!!!!!!!!!!!!!!! (0.00)
Posted by Eli Duttman on 2020-02-28, 16:41:30 (69.142.177.2)
In designs with a GNFB loop, a high pass filter at the I/P is very much in order. Allowing infrasonic noise to enter the setup can easily lead to a saturating O/P transformer core. :>(( Also, a cap. a .......
205: Tube DIY Asylum, RE: Signal wire (0.00)
Posted by Eli Duttman on 2020-02-27, 17:45:50 (69.142.177.2)
If it's line level and unshielded, anything decent will do. Tough pitch copper with PVC insulation will not do. PTFE insulation is "audiophool" approved, but ... This and this are silver plated 24 AW .......
206: Tube DIY Asylum, RE: Best transformer (0.00)
Posted by Eli Duttman on 2020-02-24, 15:20:30 (69.142.177.2)
The least stray magnetic field is associated with a toroid. AnTek offers several models well suited to tube projects and they are inexpensive. .......
207: Tube DIY Asylum, RE: thanks Eli !! (0.00)
Posted by Eli Duttman on 2020-02-20, 15:05:10 (69.142.177.2)
If forced to choose between no tone controls and tone controls that can't be defeated, I choose no tone controls. However, I choose tone controls that can be defeated and defeated is my normal mode o .......
208: Tube DIY Asylum, RE: Anyone got a schematic for a preamp w/bass&treble controls other than pas Dynaco (0.00)
Posted by Eli Duttman on 2020-02-19, 19:06:33 (69.142.177.2)
Fact, few recordings benefit from the presence of tone controls. Therefore, if incorporated in a unit, tone controls must be totally out of circuit except when in active use. Fulfilling that out of ci .......
209: Tube DIY Asylum, RE: High input or output impedance (0.00)
Posted by Eli Duttman on 2020-02-18, 15:33:17 (69.142.177.2)
Reactances store energy in force fields. That energy is, eventually, returned. Timing is critical. Things get made even more complicated by the fact that an infinite number of instantaneous power valu .......
210: Tube DIY Asylum, RE: High input or output impedance (0.00)
Posted by Eli Duttman on 2020-02-18, 15:09:25 (69.142.177.2)
Notice the word return. Reactances don't dissipate power. Remember, work = energy and power = energy/time. .......
211: Tube DIY Asylum, RE: High input or output impedance (0.00)
Posted by Eli Duttman on 2020-02-18, 14:44:34 (69.142.177.2)
Distinguish a complex impedance from a pure reactance. All real world circuits contain resistance, inductance, and capacitance. They are complex impedances and do dissipate power. If a pure reactance .......
212: Tube DIY Asylum, RE: High input or output impedance (0.00)
Posted by Eli Duttman on 2020-02-18, 10:35:50 (69.142.177.2)
No sir! "Dig" the Power Factor equation out. Power (energy/time) is a scalar quantity. Voltage and current are vector, not scalar, quantities. The scalar (dot) product of 2 vectors is the product of .......
213: Tube DIY Asylum, RE: High input or output impedance (0.00)
Posted by Eli Duttman on 2020-02-18, 07:17:37 (69.142.177.2)
Waveform fidelity is maximized, when a low impedance source drives a high impedance load. That's what you want between a preamp and power amp. A 1:10 ratio is the rule of thumb. The situation is diffe .......
214: Tube DIY Asylum, RE: High input or output impedance (0.00)
Posted by Eli Duttman on 2020-02-17, 16:19:00 (69.142.177.2)
Impedance ( Z ) is a complex number, with real (resistive) and imaginary (reactive) components. While both resistance and reactance are measured in ohms, only resistance can dissipate power. The AC fo .......
215: Tube DIY Asylum, Contact Bias Redux (0.00)
Posted by Eli Duttman on 2020-01-22, 13:55:05 (69.142.177.2)
FWIW, grid leak, AKA contact, bias works well at low signal levels. The "classic" application is the grid leak detector . Innumerable schematics show a 250 pF. cap. and 2.2 Mohm resistor. Thorsten Lös .......
216: Tube DIY Asylum, RE: Why cathode bais is normally preferred for 300B SE (0.00)
Posted by Eli Duttman on 2020-01-16, 14:52:59 (69.142.177.2)
DHTs, including the 300B, are particularly prone to runaway, when "fixed" bias is employed. To avoid said runaway, the grid to ground resistance has to be kept quite small. Low O/P impedance or transf .......
217: Tube DIY Asylum, RE: Need help with cap values replacing electrolytic with polypropylene (0.00)
Posted by Eli Duttman on 2020-01-16, 14:40:46 (69.142.177.2)
Before you even address whether or not it is safe to increase the value of those filter caps., consider the issue of volumetric efficiency. Electrolytic caps. are much more space efficient than other .......
218: Vintage Asylum, RE: They are not for removing clicks an pops... (0.00)
Posted by Eli Duttman on 2020-01-06, 16:27:35 (69.142.177.2)
There are 2 types of "single ended" noise reduction units from the time frame being discussed. The units that suppress ticks & pops pass the signal through a delay line and look for short, high inten .......
219: Vintage Asylum, RE: also the Garrard Music Recovery Module (0.00)
Posted by Eli Duttman on 2020-01-06, 01:55:06 (69.142.177.2)
I have a Burwen/KLH TNE7500(A). Less is definitely more, when using a tick & pop filter. Don't try for "dead quiet", as you will throw info. away. If you "crank" the device's effect up, lots of HF in .......
220: Tube DIY Asylum, RE: What's everyone using for volume controls these days? (0.00)
Posted by Eli Duttman on 2019-12-30, 23:28:48 (69.142.177.2)
Remove the ganged Alps control and save/sell it. Buy 2X of these and complete the current project. BTW, Mouser shows yet less costly conductive plastic parts, but I'm very dubious about them. You can' .......
221: Tube DIY Asylum, +2 (0.00)
Posted by Eli Duttman on 2019-12-30, 07:57:28 (69.142.177.2)
An unwanted satisfaction of Barkhausen's criterion is occurring and we break that up with the "stopper" resistance. .......
222: Tube DIY Asylum, RE: What's everyone using for volume controls these days? (0.00)
Posted by Eli Duttman on 2019-12-30, 05:10:07 (69.142.177.2)
Hot molded carbon has a "warmer" sound than conductive plastic. PEC of Canada's milspec tough KA series controls will serve you well. Buy them from DigiKey. .......
223: Tube DIY Asylum, RE: switching Hz = 60KHz (0.00)
Posted by Eli Duttman on 2019-12-21, 23:13:52 (69.142.177.2)
Obviously, something is resonating. :>( The data sheet for that 47 μH. part seems to omit a self resonant frequency specification. You can try tweaking the value of that pF. range cap. and see i .......
224: Tube DIY Asylum, RE: hash filter formula (0.00)
Posted by Eli Duttman on 2019-12-21, 08:03:28 (69.142.177.2)
I looked for a part with the same current rating as the common mode choke. FWIW, I usually suggest a larger inductance and a 1000 pF. cap., but current handling capability is essential. .......
225: Tube DIY Asylum, RE: SMPS DC heaters for SE 6AQ5 amp ... (0.00)
Posted by Eli Duttman on 2019-12-20, 20:23:46 (69.142.177.2)
Considering the SMPS voltage source, perhaps some trash at RF frequencies is "riding" on the DC. Think about a LC "hash" filter in front of the common mode choke you already use. It's possible for HF .......
226: Tube DIY Asylum, RE: Fundamental Concepts (0.00)
Posted by Eli Duttman on 2019-12-20, 19:41:09 (69.142.177.2)
They will use whatever maximizes profitability. If they think that omitting a stopper will "fly", they will do so. .......
227: Tube DIY Asylum, RE: Fundamental Concepts (0.00)
Posted by Eli Duttman on 2019-12-20, 18:41:48 (69.142.177.2)
The key word is might. What tube type being employed is an enormous factor, in the overall picture. A truly well, both electrically and mechanically, laid out 12AX7 circuit could easily function well .......
228: Tube DIY Asylum, Failed Volume Control (0.00)
Posted by Eli Duttman on 2019-12-20, 18:03:08 (69.142.177.2)
Once again, let's refer to the schematic. 2 items stick out like sore thumbs: the loudness taps and the 600 Kohm value. AFAIK, no "off the shelf" item exists for that 600 Kohm value. Use 500 Kohms and .......
229: Tube DIY Asylum, RE: Is the quality of grid leak resistor important? (0.00)
Posted by Eli Duttman on 2019-12-14, 22:00:10 (69.142.177.2)
IMO, you are correct about grid leak referring to biasing. However, people do use the term otherwise. Grid to ground is my take on the semantics. That seems to cover the situation, regardless of the b .......
230: Tube DIY Asylum, RE: Is the quality of grid leak resistor important? (0.00)
Posted by Eli Duttman on 2019-12-14, 15:58:06 (69.142.177.2)
Carbon comp. for grid stopper positions, where non-inductive and non-metallic matter. As current in a grid stopper is vanishingly small, CC's noise issues are of little consequence. Grid to ground, AK .......
231: Tube DIY Asylum, RE: Is the quality of grid leak resistor important? (0.00)
Posted by Eli Duttman on 2019-12-13, 22:12:31 (69.142.177.2)
I will not address the contentious matter of sonics. However, a very real issue for resistors in grid to ground positions is noise performance. For the most part, I suggest Vishay/Dale RNnn metal film .......
232: Vintage Asylum, RE: From Eli below (0.00)
Posted by Eli Duttman on 2019-12-13, 21:58:30 (69.142.177.2)
Those are the correct tubes. However, the S5000 schematic shows a single, non-adjustable, O/P tube bias connection. Therefore, the 4X O/P tubes have to be closely matched. IMO, adding an adjustment to .......
233: Vintage Asylum, RE: Sherwood S5000 Project (0.00)
Posted by Eli Duttman on 2019-12-12, 19:27:27 (69.142.177.2)
JMO, sell the 7199s and rewire the sockets. Given scarcity, NOS 7199s command pretty good money. The 6BL8, 6GH8, and 6U8 pin out indentically and are, more or less, interchangeable. All the suitable p .......
234: Vintage Asylum, RE: Sherwood S5000 Project (0.00)
Posted by Eli Duttman on 2019-12-12, 19:16:59 (69.142.177.2)
Use AA's search function to scan the Vintage, Tube, and Tube DIY "boards". .......
235: Vintage Asylum, RE: Sherwood S5000 Project (0.00)
Posted by Eli Duttman on 2019-12-12, 16:37:35 (69.142.177.2)
When it comes to O/P tubes, "there's only 1 game in town". You must use the Russian 6Π14Π-EB (6p14p-ev), AKA EL84M. Fortunately, that tougher than old rubber boots 7189 equivalent exhibits q .......
236: Vintage Asylum, RE: Yamaha CA-1010 phono section (0.00)
Posted by Eli Duttman on 2019-12-09, 06:11:29 (69.142.177.2)
Jim Hagerman's Bugle3 is better than decent and is highly affordable. BTW, it's physically small and easy to lug around. .......
237: Vintage Asylum, RE: Pioneer SA 600 Amp (0.00)
Posted by Eli Duttman on 2019-12-05, 15:00:39 (69.142.177.2)
IMO, 0.5% THD is excessive and 0.3% is acceptable. My thinking is the unit is something like 15 "honest" WPC. Can you come up with an IMD number? Pair it with speakers that are 91 dB. sensitive, or so .......
238: Tube DIY Asylum, RE: Audio Research Screen Regs problems (0.00)
Posted by Eli Duttman on 2019-12-05, 12:22:40 (69.142.177.2)
This is an example of a quarrel I have with ARC, too much complexity for (apparently) its own sake. Compare that to Michael Maida's work . .......
239: Tube DIY Asylum, RE: 6.3v DC heaters from 6.3v AC supply. (0.00)
Posted by Eli Duttman on 2019-12-05, 12:10:50 (69.142.177.2)
In addition to what's already been said, I'll add every little bit helps. If you are not using Schottky diode rectification now, make the switch post haste. Forward drop in a "PN" diode can be 1.2 V., .......
240: Tubes Asylum, RE: 60 uF (0.00)
Posted by Eli Duttman on 2019-12-02, 11:22:31 (69.142.177.2)
40 μF. is the value presented by the 5U4GB datasheet . What follows immediately is JMO. Vishay/Dale RNnn resistors are fine in grid to ground positions, as low noise is an issue here. I like the .......
241: Tubes Asylum, RE: Wisely or unwisely... (0.00)
Posted by Eli Duttman on 2019-12-01, 11:20:52 (69.142.177.2)
The 5AR4/GZ34 is rated for as much as 60 μF. in the 1st position of a CLC filter. Installing a CL-90, which is 120 Ω cold, in the line between rectifier and filter makes the situation "a pie .......
242: Tubes Asylum, RE: Thank you for the review (0.00)
Posted by Eli Duttman on 2019-11-30, 12:47:31 (69.142.177.2)
A DC link cap. in the 1st position of the CLC filter may be a possibility. Perhaps this part will do. BTW, the low ESR 105 o C. 'lytics from Panasonic and Nichicon are darned good. .......
243: Tubes Asylum, RE: Thanks Eli and Another Question (0.00)
Posted by Eli Duttman on 2019-11-23, 13:14:59 (69.142.177.2)
That will do. It's non-shorting (break before make), which is what you want in a source selector. If you're building a stepped attenuator, a shorting switch (make before break) is appropriate. ::: TOP .......
244: Tubes Asylum, RE: Elma (0.00)
Posted by Eli Duttman on 2019-11-22, 20:32:00 (69.142.177.2)
I'm not going to say the Elma part is junk, when it (obviously) is not. However, it's too damned costly. A much better (IMO) value is this Lorlin part , from Mouser. .......
245: Vintage Asylum, RE: I'm surprised Eli hasn't weighed in (0.00)
Posted by Eli Duttman on 2019-11-22, 10:56:52 (69.142.177.2)
I'll stand by what I previously said. Mix and match is 1 of the reasons for separate components. A competent non-"Mac" preamp, regardless of its "vintage", will be fine mated to the MC240. Pay careful .......
246: Tube DIY Asylum, RE: Thanks, follow up questions. (0.00)
Posted by Eli Duttman on 2019-11-13, 00:20:09 (69.142.177.2)
A "tall" B+ rail need not be a problem, when full pentode mode "finals" are employed. Very carefully regulate g2 B+ at a fraction of anode B+ and zealously adhere to the published plate dissipation li .......
247: Tube DIY Asylum, RE: 6DJ8 vs 12AU7 / 12AT7 (0.00)
Posted by Eli Duttman on 2019-11-12, 14:49:35 (69.142.177.2)
Not at all electrically close. The 6DJ8 is high gm. Of the 12A_7 bunch, the 'T7 is highest in gm, but doesn't come close to the 6DJ8. Also, the 'T7 is μ 60, while the 6DJ8 is μ 33. In a situ .......
248: Tube DIY Asylum, RE: I wouldn't use JJ's for rectifiers. (0.00)
Posted by Eli Duttman on 2019-11-12, 14:34:42 (69.142.177.2)
By all accounts, the "reissue" Mullard 5AR4 is satisfactory. Yes, JJ's Octal production is (at best) inconsistent. FWIW, my preference is for the installation of the series SS diode tweak, implemente .......
249: Tube DIY Asylum, RE: What to do with this HiWatt monstrosity? (0.00)
Posted by Eli Duttman on 2019-11-12, 14:17:25 (69.142.177.2)
Gary, How about a genuine integrated amp that includes a phono section? You have plenty of sockets to work with and power trafos of some heft. For the power section, PP 5881 equivalent Russian 6Π .......
250: Tube DIY Asylum, RE: 6c45 preamp (0.00)
Posted by Eli Duttman on 2019-11-11, 20:58:23 (69.142.177.2)
Just passing on that which has been taught to me. I avoid these trouble makers. If you search around the WWW, you'll come across info. regarding the 5842/417A showing it in true grounded grid service .......
251: Tube DIY Asylum, RE: 6c45 preamp (0.00)
Posted by Eli Duttman on 2019-11-11, 13:16:50 (69.142.177.2)
Dennis, The 6C45Π (6s45p) comes close to oscillating, just sitting in its cardboard box. :>( The type, like the 5842, is intended for grounded grid RF service. To be run common cathode, not only .......
252: Tubes Asylum, RE: fisher 800-b power draw (0.00)
Posted by Eli Duttman on 2019-10-25, 18:08:40 (69.142.177.2)
There are good sized caps. in the voltage doubler B+ PSU. A turn on surge will be present. The numbers provided seem to indicate that all is well. .......
253: Tubes Asylum, RE: If anybody comes to NJ (0.00)
Posted by Eli Duttman on 2019-10-20, 11:19:42 (69.142.177.2)
"Shaded Dogs" in decent condition are welcome. A word to the wise for "inmates" from states with "relaxed" handgun laws, leave the weapons at home! In NJ, except for law enforcement personnel, handg .......
254: Tubes Asylum, RE: You guys have to check this out (0.00)
Posted by Eli Duttman on 2019-10-19, 17:16:35 (69.142.177.2)
Yes, that's a BIG, honking, transmitting type. Mucho KV. on that anode. Route 22 near North Plainfield you say. That's not too far from me, in Monroe Township (Turnpike exit 8A). .......
255: Tube DIY Asylum, RE: Yes, but no sane owner of a tweed 5E6 Bassman... (0.00)
Posted by Eli Duttman on 2019-10-16, 14:49:15 (69.142.177.2)
A guitar amp is an effects machine. B+ sag when driven hard is good for "tone", but very bad for HIFI. Making music and reproducing music are disparate applications. Like Tim, I strongly prefer SS rec .......
256: Tube DIY Asylum, RE: Microphone Transformer Ratio question (0.00)
Posted by Eli Duttman on 2019-10-11, 05:34:29 (69.142.177.2)
Maybe try closer to home. Sowter has all sorts of "pro" stuff and they do engineer new designs. .......
257: Tube DIY Asylum, RE: 3 tube 3 watt dc coupled 6b4g practical amp design (0.00)
Posted by Eli Duttman on 2019-10-07, 06:38:00 (69.142.177.2)
Even with the hum balance resistor, AC heating a SE 6B4 rates to have an unacceptably high hum level. Ignoring the topology's merits, or lack thereof, a 2A3 is a much better AC heating candidate. ::: .......
258: Tubes Asylum, RE: Then you are really missing out. (0.00)
Posted by Eli Duttman on 2019-10-06, 20:52:35 (69.142.177.2)
I was not referring to you. The children I was talking about are tubes and BJTs. John Curl and Nelson Pass are HIGHLY competent designers of SS equipment. Few, if any, can match their skill in handlin .......
259: Tubes Asylum, RE: Then you are really missing out. (0.00)
Posted by Eli Duttman on 2019-10-06, 18:41:55 (69.142.177.2)
FETs are nice. FETs (like tubes) are voltage controlled, high impedance, devices. Think heaterless pentode. ;>) BJTs are a different matter. I'm not saying BJTs can't be made to work well. Crossing s .......
260: Vintage Asylum, RE: I would use banana to pin adaptors, link. (0.00)
Posted by Eli Duttman on 2019-10-06, 13:01:05 (69.142.177.2)
It's nice to know that an off the shelf solution is available. :up: :>) .......
261: Vintage Asylum, RE: New speakers/vintage amp (0.00)
Posted by Eli Duttman on 2019-10-06, 09:55:55 (69.142.177.2)
"What's a twin binding post?" This is a twin binding post. "I guess the part that you linked to goes into the old binders on my amp I guess?" Yes, the pin goes into the clip. .......
262: Vintage Asylum, RE: New speakers/vintage amp (0.00)
Posted by Eli Duttman on 2019-10-06, 09:02:32 (69.142.177.2)
Make adapters from twin binding posts, short lengths of cabling, and these . Yes, you could cut the banana plugs off, but loosing flexibility makes no sense to me. .......
263: Tubes Asylum, RE: olson preamp AM221 (0.00)
Posted by Eli Duttman on 2019-10-05, 21:23:16 (69.142.177.2)
The RCA setup is good, but it too "can't fight its way out of a wet paper bag". Notice the 220 Kohm load requirement. FWIW, I'm associated with a tweaked version of the RCA that does have drive capabi .......
264: Tube DIY Asylum, RE: Eico OPTs - 6P3S-E, Thx (HF87 schematic) (0.00)
Posted by Eli Duttman on 2019-10-05, 18:12:22 (69.142.177.2)
TK, the 1st post in this thread shows "iron" that doesn't have UL taps. Full pentode mode is "the only game in town". Carefully regulate g2 B+ and crank anode B+ up, while relentlessly holding anode d .......
265: Tube DIY Asylum, RE: Eico OPTs (0.00)
Posted by Eli Duttman on 2019-10-05, 16:55:23 (69.142.177.2)
Uh, huh. Soviet era milspec stuff does tend towards toughness. .......
266: Tube DIY Asylum, RE: Eico OPTs (0.00)
Posted by Eli Duttman on 2019-10-04, 21:33:25 (69.142.177.2)
Take it easy with the Cit. 5. Remember, the OEM tube is the 7581, which is more capable than the 5881. .......
267: Tubes Asylum, RE: olson preamp AM221 (0.00)
Posted by Eli Duttman on 2019-10-04, 21:00:46 (69.142.177.2)
That's a GE style preamp executed with 12AX7s, instead of a 6SC7, like that found in the Fisher model whose schematic I'm uploading. That style has an incorrect I/P impedance for modern MM level cartr .......
268: Tube DIY Asylum, RE: Eico OPTs Cit V (clone pic) (0.00)
Posted by Eli Duttman on 2019-10-04, 11:20:42 (69.142.177.2)
Talk to Jim McShane about both the Cit. 5 "iron" impedance and working some sort of swap out for the 12BY7s. .......
269: Tube DIY Asylum, RE: Eico OPTs - 6P3S-E, Thx (HF87 schematic) (0.00)
Posted by Eli Duttman on 2019-10-04, 10:54:54 (69.142.177.2)
Remember what I said about otherwise satisfactory tubes biasing "all over the place". You picked a good "church", but the wrong "pew". Check the HF-89 out. .......
270: Tube DIY Asylum, RE: Eico OPTs (0.00)
Posted by Eli Duttman on 2019-10-04, 10:45:06 (69.142.177.2)
FWIW, I'm leery of anything other than "6.6" Kohm primary "iron" in combination with 6L6 family tubes. The 6Π3C-E (6p3s-e) is a 5881 equivalent and definitely a 6L6 family member. TK, you say tha .......
271: Tube DIY Asylum, RE: Eico OPTs and recommended circuit question (schematic) (0.00)
Posted by Eli Duttman on 2019-10-03, 17:58:44 (69.142.177.2)
Pete, Either you go with PPP "12" W. tubes or PP EL34 class tubes. 6V6 family tubes are just as good a mate as 6BQ5/EL84s. I advise "fixed" bias, with individual trim pots., if the PPP option is selec .......
272: Tube DIY Asylum, RE: Bypassing Capacitors (0.00)
Posted by Eli Duttman on 2019-09-26, 20:20:32 (69.142.177.2)
People design as if the parts behave in an ideal manner. They definitely do not. Bypassing caps. in important circuit positions can make things better approximations of ideal. .......
273: Tube DIY Asylum, RE: Bypassing Capacitors (0.00)
Posted by Eli Duttman on 2019-09-26, 19:25:09 (69.142.177.2)
The big reason for bypassing, is a reduction in equivalent series resistance (ESR) and equivalent series inductance (ESL). Small value parts tend to perform much better in those "departments". Remembe .......
274: Vintage Asylum, RE: Thanks! (0.00)
Posted by Eli Duttman on 2019-09-17, 08:05:07 (69.142.177.2)
I don't think you are a digital source only guy. So, what are you going to use for a phono stage? An "axe" man, like you, surely has some nice 'X7s on his "pile". .......
275: Vintage Asylum, RE: OK but Columbia also asked George Szell the same question. (NT) (0.00)
Posted by Eli Duttman on 2019-09-09, 08:26:11 (69.142.177.2)
True enough. The key point being that the musicians called the "shots" and great recordings were laid down. These days sadly, the folks tweaking their digital dodads show themselves, instead of the mu .......
276: Vintage Asylum, RE: Chasing the Dragon (0.00)
Posted by Eli Duttman on 2019-09-09, 08:19:21 (69.142.177.2)
Fritz! .......
277: Vintage Asylum, RE: Chasing the Dragon (0.00)
Posted by Eli Duttman on 2019-09-09, 00:43:18 (69.142.177.2)
Jerry, you've made an important point. The recording/processing people need to serve the music, not massage their own egos. Think back to when RCA's folks said, Mr. Reiner is that what you want? ::: T .......
278: Tube DIY Asylum, RE: Does anyone know why Jack would not use NFB in this design? (0.00)
Posted by Eli Duttman on 2019-08-31, 22:54:30 (69.142.177.2)
"It is impressive that this could sound very good on one set of speakers and absolutely broken on others." Quite marginal damping factor is the likely reason. While not nearly as lacking in voice coil .......
279: Tube DIY Asylum, RE: 50EH5 SE Amp (0.00)
Posted by Eli Duttman on 2019-08-29, 14:23:30 (69.142.177.2)
So, 1 bottle per channel. The 6BM8 setup provided should get things done. Here, the "final" operates in ultra-linear (UL) mode. .......
280: Tube DIY Asylum, RE: 50EH5 SE Amp (0.00)
Posted by Eli Duttman on 2019-08-28, 20:02:51 (69.142.177.2)
I found the write up. Look here . While inspiration can be drawn, the circuitry shown leaves a LOT to be desired. Full pentode mode without NFB of some kind exhibits a wretched damping factor. :>(( Ca .......
281: Tube DIY Asylum, RE: 50EH5 SE Amp (0.00)
Posted by Eli Duttman on 2019-08-27, 22:27:58 (69.142.177.2)
Always start with the datasheet . 0B2 regulate g2 B+, for both safety and best full pentode mode open loop distortion. A "170" V. anode B+ will be safe, IF plate dissipation is strictly held within .......
282: Tubes Asylum, RE: Won't the final dropping voltage change? Thanks! (n/t) (0.00)
Posted by Eli Duttman on 2019-08-22, 03:14:49 (69.142.177.2)
Yes, it will. That's why the resistance value needs reworking, as a matter of safety. It's a simple Ohm's Law calculation. Unfortunately, as P = I 2 R, the amount of waste heat generated is considerab .......
283: Tubes Asylum, RE: string filament question (0.00)
Posted by Eli Duttman on 2019-08-21, 18:25:55 (69.142.177.2)
In a series string, the current is the same everywhere. As built, you have a 150 mA. string. You could convert to a 300 mA. string, BUT the isolation trafo might be overworked and you will generate mo .......
284: Tubes Asylum, RE: Started looking through some boxes and I must be insane. . . (0.00)
Posted by Eli Duttman on 2019-08-17, 17:45:18 (69.142.177.2)
As long as heat is not a problem, polystyrene is an excellent choice. The dielectric absorption "pecking order" is PTFE, polystyrene, polypropylene. Polyester definitely brings the rear up, among film .......
285: Radio Road, RE: Sending AM signals down the house' FM coax?! feasible? (0.00)
Posted by Eli Duttman on 2019-08-16, 21:55:53 (69.142.177.2)
I suspect that your household coax is RG6 category. RG6 is an improvement over RG59 that can handle higher frequency signals. Carrying "medium wave" AM signals should be "a piece of cake". A huge rub .......
286: Tubes Asylum, RE: Wima FKP2....nt (0.00)
Posted by Eli Duttman on 2019-08-16, 00:51:47 (69.142.177.2)
Price was a mentioned criterion. So, I agree with the suggestion. Mouser charges 35 cents/part. $2.79 buys 10 parts. Look here . .......
287: Tube DIY Asylum, RE: Is there a date code on the older ones like Sprague VitQ? (0.00)
Posted by Eli Duttman on 2019-08-11, 13:04:05 (69.142.177.2)
Mechanical leakage is the issue. Vit. Qs found in signal positions are hermetically sealed and are fine. Look for evidence of a glass to metal seal in those large parts. .......
288: Tube DIY Asylum, RE: PIO filter/psu (oil-can ?) caps. Are there any without PCBs inside? (0.00)
Posted by Eli Duttman on 2019-08-10, 19:04:01 (69.142.177.2)
Tim, An oil cap. that predates the introduction of PCBs and is leak free should be fine. So, it's a date range, which should be avoided. Jim Dowdy gave us 1979 as range's end. I don't know when GE int .......
289: Vintage Asylum, RE: Ping Eli Duttman (0.00)
Posted by Eli Duttman on 2019-08-09, 15:23:18 (69.142.177.2)
Let's be clear, neither the tweak nor the graphic originate with me. I'm merely spreading the info. about something quite useful. Wire each 5AR4 per the graphic. Treat each socket as a composite entit .......
290: Tubes Asylum, RE: Allen-Bradley (0.00)
Posted by Eli Duttman on 2019-08-01, 19:37:54 (69.142.177.2)
The OS Allen Bradley, Stackpole, and Ohmite CC parts may have absorbed moisture, over time. Bake them in an oven, followed by a value check using a good multi-meter. Ohmite still makes CC resistors. T .......
291: Tubes Asylum, RE: Grid stoppers. Best quality and composition? (0.00)
Posted by Eli Duttman on 2019-07-30, 16:59:00 (69.142.177.2)
Carbon comp., as that construction is both non-metallic and non-inductive. Noise tends to be a non-issue, as currents in control grid circuits are vanishingly small. Tantalum nitride may be better tha .......
292: Tubes Asylum, RE: Complimentary tube combos for BHK PRE/250 combo (0.00)
Posted by Eli Duttman on 2019-07-24, 15:27:07 (69.142.177.2)
I don't know the equipment. Is extra heater current available? If it is, a 12BH7 rates to be an improvement over any 12AU7 . The 'U7 is fundamentally non-linear and is (IMO) acceptable only in the cat .......
293: Tube DIY Asylum, RE: 6P3S-e question (0.00)
Posted by Eli Duttman on 2019-07-20, 09:23:59 (69.142.177.2)
The 6Π3C-E (6p3s-e) is a 5881 equivalent. I have no qualms about reaching the conservative design center 23 W. plate dissipation limit. Don't forget the 3 W. g2 dissipation limit. .......
294: Tube DIY Asylum, RE: Gain Structure Considerations (0.00)
Posted by Eli Duttman on 2019-07-07, 21:28:29 (69.142.177.2)
Your amp has a 100 Kohm I/P impedance and 1.3 VRMS sensitivity for rated power. The full 2 VRMS O/P of a "standard" CDP will drive the unit into clipping. You can experiment with passive control at lo .......
295: Tube DIY Asylum, Gain Structure Considerations (0.00)
Posted by Eli Duttman on 2019-07-07, 15:10:52 (69.142.177.2)
What drive level is needed by your power amplifier? Heavily attenuating a signal before feeding it into a line stage whose gain is substantial has an adverse impact on overall S/N performance. Quite a .......
296: Tube DIY Asylum, RE: Anthem Pre-1L Sell or Modify? (0.00)
Posted by Eli Duttman on 2019-07-06, 17:51:10 (69.142.177.2)
Sell the "Anthem"! It is surely made with a PCB and significant modification rates to be highly problematic. BFD about the "Daniel" having only MM phono capability. Add step up transformers to your ri .......
297: Vintage Asylum, RE: Wide audio band-width AM is worth having IF you have stations worth bothering with. (0.00)
Posted by Eli Duttman on 2019-06-29, 16:47:19 (69.142.177.2)
As a music source in the U.S., AM radio is "shot". There may not be a "top 40" station left. As for other genres, the days of WQXR, WNEW, and WPAT are long gone. Decades ago, the FCC mandated differen .......
298: Tube DIY Asylum, RE: 1958 Hafler Article (0.00)
Posted by Eli Duttman on 2019-06-27, 13:26:51 (69.142.177.2)
Is the cell size significant? I would think not. It's the fresh carbon-zinc chemistry that yields the correct reference voltage. Now in 1958, carbon-zinc "D" cells were ubiquitous. Flashlights, for st .......
299: Tubes Asylum, RE: 12SL7 variants? (0.00)
Posted by Eli Duttman on 2019-06-24, 17:13:08 (69.142.177.2)
FWIW, the Loctal 14F7 gets my vote. Even though Sylvania used the same "cages" in both Octal and equivalent Loctal types, the mechanical construction of Loctal types (with their intended mobile servic .......
300: Tubes Asylum, RE: What do I got here? (0.00)
Posted by Eli Duttman on 2019-06-22, 18:00:41 (69.142.177.2)
I leave the code deciphering to those in the know. Silk screen branding and boxing mean nothing, in this case. RCA never manufactured 6DJ8 family tubes in the plants that they owned. .......
301: Vintage Asylum, RE: Can I use HK 330C with external power amp? (0.00)
Posted by Eli Duttman on 2019-06-22, 17:53:48 (69.142.177.2)
While there are exceptions, the usual arrangement is for recording O/Ps to be connected to the source selector switch and the preamp section, including level setting, has not acted on the signal. A fa .......
302: Vintage Asylum, RE: rare edition with type 46 (0.00)
Posted by Eli Duttman on 2019-06-19, 04:04:35 (69.142.177.2)
The #46 is always wired as a triode. Either the 2nd grid is tied to the plate and the tube behaves much like a #45 or the 2 grids are tied together and the tube naturally operates in Class "B2". ::: T .......
303: Tubes Asylum, RE: Half Of A 6DJ8? (0.00)
Posted by Eli Duttman on 2019-06-16, 10:20:35 (69.142.177.2)
What's the application? While its triode is higher μ, etc., the 6GK5 might meet your needs. .......
304: Tube DIY Asylum, RE: Pardon my ignorance but....what? (0.00)
Posted by Eli Duttman on 2019-06-15, 14:21:40 (69.142.177.2)
It was the score of the National Championship Game. Quite a few of the young men playing on both squads will be playing on Sundays. .......
305: Vintage Asylum, RE: What are the output tubes that the amp is using? (n/t) (0.00)
Posted by Eli Duttman on 2019-06-15, 07:58:53 (69.142.177.2)
The Scott 200 uses the 6GW8/ECL86. The library version of the schematic is here . .......
306: Tubes Asylum, RE: I got some (0.00)
Posted by Eli Duttman on 2019-06-14, 12:47:21 (69.142.177.2)
Bendix "Red Bank" tubes make the proverbial brick outhouse look like a total piker. .......
307: Tube DIY Asylum, RE: finally, an amp that may give my SE 2A3 a run ...... (0.00)
Posted by Eli Duttman on 2019-06-13, 07:57:00 (69.142.177.2)
Be prepared for inadequate voice coil damping, when you try UL mode. .......
308: Tubes Asylum, RE: Differences between the KT-66 and KT-77 (0.00)
Posted by Eli Duttman on 2019-06-10, 11:32:40 (69.142.177.2)
THE issue with JJ is inconsistency. When it comes to JJ's Octal production, it's "a pig in a poke". Both decent tubes and "floor sweepings" are possibilities. New Sensor or JJ, buy from a dealer who .......
309: Tubes Asylum, RE: To judge the EL34 sound on the Shuguang is to judge.... (0.00)
Posted by Eli Duttman on 2019-06-09, 20:18:46 (69.142.177.2)
What amp? What speakers? Which room? Whose ears? What musical material? The factors go on and on. While silly expensive, we know XF4 Mullard EL34s are terrific. St. Petersburg made =C= EL34s have a su .......
310: Tubes Asylum, RE: What's wrong with EL34? Nt (0.00)
Posted by Eli Duttman on 2019-06-09, 20:03:18 (69.142.177.2)
What you observe is the difference in distortion spectrum between a beam power tetrode and a true, 3 grid, pentode. The consequences of stuctural difference will hold true, even when the variants are .......
311: Tubes Asylum, RE: Russian 6p3c-e (0.00)
Posted by Eli Duttman on 2019-06-04, 19:42:30 (69.142.177.2)
Yes, the 5881 that New Sensor sells is 6Π3C-E (6p3s-e) . .......
312: Tubes Asylum, RE: JJ KT77's (0.00)
Posted by Eli Duttman on 2019-06-03, 14:51:49 (69.142.177.2)
All of JJ's Octal production remains suspect, at least for those "inmates" based in North America. If you're in North America, stick to "reissue" Genelex sourced from a reliable dealer. .......
313: Tube DIY Asylum, RE: Bob design the power supply to use... (0.00)
Posted by Eli Duttman on 2019-05-30, 22:11:46 (69.142.177.2)
The GZ37 is a poor substitute for the 5AR4/GZ34 . In addition to the 3 A. heater and greater forward drop, the previously mentioned 4 μF. vs. (sic) 60 μF. sticks out like a sore thumb. Caref .......
314: Tube DIY Asylum, RE: Contempt prior to investigation (0.00)
Posted by Eli Duttman on 2019-05-26, 17:23:15 (69.142.177.2)
Since you mentioned WIMA, how about this FKP part ? Other than the 5 mm. lead spacing, I see very little negative and several positives, including a 50 cent price. .......
315: Tube DIY Asylum, RE: Thank you (0.00)
Posted by Eli Duttman on 2019-05-25, 18:48:10 (69.142.177.2)
FWIW, if you "sniff" around the Scott schematic archive, you'll see that the 6GH8, 6U8, and 6BL8 are more or less interchangeable. I guess it's time to add the 7643 to the bunch. Thank you, Cleantimes .......
316: Tube DIY Asylum, RE: For only a dime more (0.00)
Posted by Eli Duttman on 2019-05-23, 19:44:07 (69.142.177.2)
Unlike other ceramic dielectrics, C0G/NP0 is good in the signal path. It's not only the low price. Both volumetric efficiency and heat tolerance are better than the film part you linked. Provided it m .......
317: Tube DIY Asylum, RE: After pulling the 4 ax7s the bias voltage came up.. (0.00)
Posted by Eli Duttman on 2019-05-22, 21:03:27 (69.142.177.2)
Putting a NTC thermistor on the primary side of the power trafo will slow everything down. You want to slow B+ down and leave the negative supply alone. Put the CL-80 in the line that connects the pow .......
318: Tube DIY Asylum, FYI, $0.63 Part (0.00)
Posted by Eli Duttman on 2019-05-22, 14:53:10 (69.142.177.2)
Look here . .......
319: Tube DIY Asylum, Ceramic Dielectric in the Signal Path (0.00)
Posted by Eli Duttman on 2019-05-22, 14:38:21 (69.142.177.2)
For whatever reason, if and when ceramic dielectric caps. are placed in the signal path, make damned sure that they are C0G/NP0. BTW, has anybody tried a 6BL8 in Mr. Gillespie's board? .......
320: Tube DIY Asylum, RE: Ping Eli - El Cheapo (0.00)
Posted by Eli Duttman on 2019-05-20, 19:43:34 (69.142.177.2)
The project was cost driven. Magnetics are always the big $ in any project. Back then, the guitar amp O/P trafo shown was a good deal. That's no longer the case. Triode wiring was a given and wimpy 12 .......
321: Tubes Asylum, RE: Love Smooth Plate Tele 12ax7s but.... (0.00)
Posted by Eli Duttman on 2019-05-20, 19:03:10 (69.142.177.2)
Talk to AA sponsor Jim McShane about some Sovtek 12AX7LPSes. The 'LPS is clean and quiet. IIRC, New Sensor has done a quite respectable job of "cloning" the Siemens "long plate". Too bad EI is defunct .......
322: Vintage Asylum, RE: A Path Forward (0.00)
Posted by Eli Duttman on 2019-05-18, 21:30:55 (69.142.177.2)
Nothing new about dealing with budget realities. How about a Parasound 2125 v.2 amp and helping the OP DIY a 12B4 line stage? While the Parasound amp does not have a great PSU, it does seem to have mo .......
323: Vintage Asylum, RE: A Path Forward (0.00)
Posted by Eli Duttman on 2019-05-18, 19:41:45 (69.142.177.2)
"Continuous Average Power: 110 watts per channel, 20 Hz - 20kHz, 165 watts per channel, 20 Hz - 20kHz, Based on the above, I vote NO regarding the the "Outlaw" receiver. There are inadequate reserves .......
324: Tube DIY Asylum, RE: Electraprint DRD 300B (0.00)
Posted by Eli Duttman on 2019-05-18, 00:19:13 (69.142.177.2)
Maybe this will help. It's a chart of 300B operating conditions sets. .......
325: Vintage Asylum, RE: What to Do? (0.00)
Posted by Eli Duttman on 2019-05-17, 20:07:51 (69.142.177.2)
FWIW, I agree with the tubes suggestion, particularly in the preamp area. More than 1 very nice sounding rig has used tubed preamplification combined with quality SS power amplification. I'm guessing .......
326: Tube DIY Asylum, RE: It's Wishful thinking (0.00)
Posted by Eli Duttman on 2019-05-17, 00:30:47 (69.142.177.2)
Tre', Look at the schematic. The decoupling network resistors are only 100 Ω, which is inadequate. Voltage drop considerations bar more resistance. Come Hell or high water, the diodes will block .......
327: Tube DIY Asylum, RE: It's Wishful thinking (0.00)
Posted by Eli Duttman on 2019-05-16, 18:30:34 (69.142.177.2)
For the sake of argument, let's assume you are correct. The current cost, at Mouser, of 2X UF4007s is 82 cents, which is very low cost insurance against trouble. Not collecting on insurance is commonp .......
328: Tube DIY Asylum, RE: No, you didn't (0.00)
Posted by Eli Duttman on 2019-05-15, 22:30:32 (69.142.177.2)
You've got things backwards. The diodes stop the "finals" from impacting on the small signal reservoirs. .......
329: Tube DIY Asylum, RE: No, you didn't (0.00)
Posted by Eli Duttman on 2019-05-14, 18:58:14 (69.142.177.2)
"There's no reservoir cap on the downstream side of these diodes." Look at the schematic again. There's a 50 μF. 'lytic bypassed by a 4.7 μF. MKP in each channel. Those capacitances feed the .......
330: Tube DIY Asylum, RE: Blocks back-flow of AC? (n/t) (0.00)
Posted by Eli Duttman on 2019-05-14, 14:21:30 (69.142.177.2)
Blocks back flow of charge, when and if a decoupling cap. is at a higher potential than another circuit section. The leading candidates for a problem are peak power O/P and a substantial disparity in .......
331: Tube DIY Asylum, RE: Those diodes can't do that (0.00)
Posted by Eli Duttman on 2019-05-14, 09:33:23 (69.142.177.2)
The diodes are "check valves". They decouple the 2 channels' small signal circuitry from the "finals" and each other. Notice the resistance in the decoupling networks is low, too low. That "decision" .......
332: Tube DIY Asylum, RE: DRD 300B power supply (0.00)
Posted by Eli Duttman on 2019-05-13, 19:14:54 (69.142.177.2)
Do you already own any 5AR4s? Have you already acquired a power transformer? The max. PIV for the GZ34/5AR4 is 1500 V. A 550 V. rail FWCT setup exceeds that limit, before inevitable losses (including .......
333: Radio Road, RE: Curious antenna connection on Lafayette LT-D10 (0.00)
Posted by Eli Duttman on 2019-05-07, 10:21:59 (69.142.177.2)
I read the schematic exactly as you do. That thing is DANGEROUS. Replace the 1000 pF. cap. with a part rated for both across AC mains duty and several KV working voltage. A polarized 2 conductor or 3 .......
334: Tube DIY Asylum, RE: High Power Push Pull Amp using Type 27 Driver Tubes (0.00)
Posted by Eli Duttman on 2019-05-03, 10:53:14 (69.142.177.2)
"Use it as a preamp." Exactly! The #27 exhibits a low amplification factor (μ) and low transconductance (gm). The type was developed with AM radio in mind. .......
335: Tubes Asylum, RE: The effect of a rectifier tube on sound (0.00)
Posted by Eli Duttman on 2019-05-01, 23:55:36 (69.142.177.2)
You hit on the KEY point. Get the Physics right! The only effect "rolling" rectifiers of the same type can have is on the B+ rail voltage. Changing the B+ rail voltage definitely can have an impact. K .......
336: Tubes Asylum, RE: Sorry, I meant 6AQ5 not 6BQ5 . . (0.00)
Posted by Eli Duttman on 2019-04-26, 10:01:51 (69.142.177.2)
There is a HUGE difference between the 6Π14Π and the 6Π14Π-EB, AKA EL84M. The former is a quite mediocre EL84/6BQ5 "equivalent". The latter is a good 7189 equivalent that's the sal .......
337: Tubes Asylum, RE: More or less but the operating points and characteristics of the . . (0.00)
Posted by Eli Duttman on 2019-04-26, 00:56:52 (69.142.177.2)
The Russian 6Π1Π (6p1p) is NOT electrically equivalent to the 6BQ5/EL84. It is electrically close to the 6V6, 6AQ5, 6CM6 ... The Russian 6Π14Π (6p14p) is a 6BQ5/EL84 "equivalent". .......
338: Tubes Asylum, RE: I thought the 6BQ5 was the 6V6 equivalent? n.t. (0.00)
Posted by Eli Duttman on 2019-04-26, 00:46:04 (69.142.177.2)
6BQ5 is the US designation for the EL84, a true power pentode. The 6V6 clan, including the 6AQ5, are beam power tetrodes. Look at the datasheets, for yourself. 6BQ5/EL84 6V6 6AQ5 .......
339: Tubes Asylum, RE: Anyone know the settings on a Hickok to test a 6P1P? (0.00)
Posted by Eli Duttman on 2019-04-25, 15:57:49 (69.142.177.2)
IIRC, the 6Π1Π (6p1p) qualifies as a member of the 6V6 clan. If your tester will allow a 9 pin socket with 6AQ5 parameters, you are good to go. .......
340: Tubes Asylum, RE: Anyone know where I can find a 600k stereo volume pot (0.00)
Posted by Eli Duttman on 2019-04-23, 20:59:45 (69.142.177.2)
The loudness contour switch is a royal PITA. The schematic shows signal shaping elements in the signal path, even when said switch is in the "out" position. :>( The only thing I can come up with that .......
341: Vintage Asylum, RE: Cardas makes some nice binding posts.... (0.00)
Posted by Eli Duttman on 2019-04-17, 10:33:59 (69.142.177.2)
If the Cardas stuff causes sticker shock, check out the offerings of Superior Electric, which are carried by Allied Electronics. SE is costly, but not nearly so dear as Cardas. FWIW, the late Bob Crum .......
342: Tubes Asylum, RE: Looking for a Musical Fidelity X10-V3 (0.00)
Posted by Eli Duttman on 2019-04-16, 15:39:54 (69.142.177.2)
I took a look at some Broskie info. He explicitly supports the ECC99, with his PCBs. That type draws less heater current and tolerates "taller" B+ rails than the other so called super triodes. The O/P .......
343: Tubes Asylum, RE: Why did you create this crosspost? (0.00)
Posted by Eli Duttman on 2019-04-16, 15:07:55 (69.142.177.2)
My personal experience with honest tube preamps driving SS power amps has been satisfactory. I dislike outright effects machines. Yes, where voicing ends and effects begin is highly subjective. ::: T .......
344: Tubes Asylum, RE: When Eli asks..... (0.00)
Posted by Eli Duttman on 2019-04-16, 11:15:53 (69.142.177.2)
It's a pretty safe bet that all the sources, which are commercial, are capable of driving the 10 Kohm IHF "standard" load. A 100 Kohm pot. will be "child's play". OTOH, we have to prepare for the poss .......
345: Tube DIY Asylum, RE: In that case, he needs a good phono pre-amp (0.00)
Posted by Eli Duttman on 2019-04-16, 10:04:05 (69.142.177.2)
AFAIK, Creek SS phono preamps have a decent reputation. My thinking is line stage 1st. If things need further tweaking, a tubed phono preamp can be considered. BTW, that "Seduction" is gone. EBone sug .......
346: Tubes Asylum, RE: Looking for a Musical Fidelity X10-V3 (0.00)
Posted by Eli Duttman on 2019-04-16, 09:08:06 (69.142.177.2)
Hmmm, a Broskie PCB may be just what the Dr. ordered, for somebody with limited DIY experience. I worry about potential issues with the 10 Kohm IHF "standard" I/P impedance. That's why I suggested (on .......
347: Tubes Asylum, The Discussion Is Underway (0.00)
Posted by Eli Duttman on 2019-04-16, 07:50:04 (69.142.177.2)
Look here . .......
348: Tube DIY Asylum, RE: Eli, is this for a phono input section? (0.00)
Posted by Eli Duttman on 2019-04-16, 07:38:53 (69.142.177.2)
No "surgery" needed. The SS integrated amp has all the key features: a tape monitor loop and preamp-out/amp-in. The source selector drives the recording O/Ps, which can feed a tubed line stage. That t .......
349: Tube DIY Asylum, Knowledge Contributions Needed (0.00)
Posted by Eli Duttman on 2019-04-16, 05:32:07 (69.142.177.2)
Guys, please look at and post in this thread . Things seem to have come down to a buffered volume control. FWIW, I'm thinking resistively loaded ECC99 or 6H30Π (6n30p) section cathode followers, .......
350: Tubes Asylum, RE: Looking for a Musical Fidelity X10-V3 (0.00)
Posted by Eli Duttman on 2019-04-16, 05:02:55 (69.142.177.2)
Refer to the provided specifications snapshot. Notice that 620 mV. (0.62 V.) sensitivity. Given the 2 V. O/P of a "standard" CDP, gain in the line stage is not required. A buffered volume control fits .......
351: Tubes Asylum, RE: Looking for a Musical Fidelity X10-V3 (0.00)
Posted by Eli Duttman on 2019-04-14, 14:54:19 (69.142.177.2)
Instead of using an effects machine, take full advantage of the unit's best capabilities. The tape out jacks allow you to use the phono section and source selector to drive a tubed line stage. That li .......
352: Vintage Asylum, RE: Sherwood 5000ll- speaker terminal posts suggestions? (0.00)
Posted by Eli Duttman on 2019-04-03, 01:42:41 (69.142.177.2)
If banana plugs on the cable ends is what you have in mind, you can easily do it yourself. Buy 2 of these and 2 of these . Remove the screws and twist the adapters in. Definitely use anhydrous isoprop .......
353: Tube DIY Asylum, RE: So comparing 6V6GT subtype to the EL84 (0.00)
Posted by Eli Duttman on 2019-03-29, 20:27:59 (69.142.177.2)
For HIFI, using multi-grid mode "finals", it's "neck and neck". Triode wiring is a different story. To get better sound, in this power range, than that produced by a triode wired 6V6 family tube requi .......
354: Tubes Asylum, RE: Well i do agree with a couple of your points...... (0.00)
Posted by Eli Duttman on 2019-03-27, 20:46:59 (69.142.177.2)
"Can't stand modern manufacturers calling their tubes "Mullard" or "Gold Lion" or "Telefunken". That should be illegal." Fact, brand names are property. New Sensor has "cleverly" acquired the rights t .......
355: Tube DIY Asylum, RE: SE DC pentode/tetrode finals : separate g2 supplies ... (0.00)
Posted by Eli Duttman on 2019-03-27, 09:06:23 (69.142.177.2)
What type of distortion were you looking at? Max. open loop linearity of full pentode mode "finals" is obtained when g2 B+ is regulated at a fraction of anode B+. In particular, highly irritating inte .......
356: Vintage Asylum, RE: Front plate screws for Bogen DB20 DF (0.00)
Posted by Eli Duttman on 2019-03-23, 20:17:26 (69.142.177.2)
There is a 4-48 thread screw and yet smaller. Look here . .......
357: Tubes Asylum, RE: What is a good sub for the 12AU7? (0.00)
Posted by Eli Duttman on 2019-03-21, 16:35:35 (69.142.177.2)
The 12AU7 is non-linear and makes a poor voltage amplifier. :>(( Is extra heater current available? If, and only if, sufficient extra heater current is available, a linear 12BH7 can be substituted for .......
358: Tubes Asylum, RE: Is there any information on which "boutique" caps are sealed. . . (0.00)
Posted by Eli Duttman on 2019-03-19, 09:39:09 (69.142.177.2)
Dunno if any are properly sealed. Quite a few are known to lack hermetic seals. JMO, if PIO caps. "float your boat", stick to K40s or OS U.S. made. A hermetic seal TRULY makes a huge difference. ::: T .......
359: Tubes Asylum, RE: Depends on how they are sealed. (0.00)
Posted by Eli Duttman on 2019-03-19, 01:47:08 (69.142.177.2)
Hermetic sealing is KEY. Soviet surplus K40s are properly sealed and (for now) remain a good value. OS Vit. Q and Gudeman are fine too, but the price "bites". There are costly "boutique" PIOs out ther .......
360: Tube DIY Asylum, RE: Schottky Diode Question (0.00)
Posted by Eli Duttman on 2019-03-18, 13:53:18 (69.142.177.2)
AFAIK, the high PIV silicon carbide (SiC) Schottkys do not come in axial lead packages. You could rework a traditional FWCT PSU into a "cockeyed bridge". In theory, the diode wired to the CT, through .......
361: Vintage Asylum, RE: Eli, thanks so much. Another question. (0.00)
Posted by Eli Duttman on 2019-03-17, 18:00:03 (69.142.177.2)
Positive ground can cap. = O/P tube bias supply and preamp DC heater supply. :>(( Quadruple phooey! Not replacing ALL 'lytics periodically is asking for major headaches. The caveat applies to both tub .......
362: Tubes Asylum, RE: Could you please explain what the hell you mean??? (0.00)
Posted by Eli Duttman on 2019-03-17, 10:16:00 (69.142.177.2)
Many a NFB setup has a phase compensation cap. in it. Perhaps that's what Tim meant. MKP is code for metalized polypropylene. .......
363: Vintage Asylum, RE: Looking for Jewel for Scott 222a... (0.00)
Posted by Eli Duttman on 2019-03-17, 10:06:36 (69.142.177.2)
My read of the schematic shows a neon bulb powered off the positive rail. Consider replacing the missing "jewel" plus the bulb with a jumbo red LED. The value of R216 would have to be reworked. ::: TO .......
364: Radio Road, RE: Look at what Yamaha's (still) got in 2-ch receivers (0.00)
Posted by Eli Duttman on 2019-03-15, 20:01:04 (69.142.177.2)
Mark, will Yamaha's current R-S202 pass muster? Multiple vendors sell it at $130. Yamaha has "better", but a quick glance by me suggests you're buying convenience, not performance, for the extra $. :: .......
365: Radio Road, RE: Modern Stereo Receiver w/ excellent FM/AM performance -Recommendations Please (0.00)
Posted by Eli Duttman on 2019-03-15, 00:03:36 (69.142.177.2)
For roughly $500 this may be of interest. Unfortunately, no AM, but that may be a non-issue. It's very tough (impossible?) to find music of any kind on AM, these days. BTW, scan the archives for posts .......
366: Tubes Asylum, RE: Some units are very hard on tubes... (0.00)
Posted by Eli Duttman on 2019-03-13, 17:39:34 (69.142.177.2)
Rant on. Exceeding published limits in a commercial product is a design defect! Rant off. Yes, the problem is most definitely not a new phenomenon. .......
367: Tube DIY Asylum, RE: what's a good coupling cap for HF87 ? (0.00)
Posted by Eli Duttman on 2019-03-13, 12:57:39 (69.142.177.2)
Not 715Ps, with their steel leads, but 716Ps whose leads are copper. Soviet surplus K40 paper in oil (PIO) caps. are excellent and (at least for now) affordable. .......
368: Tubes Asylum, RE: They are 8ohm speakers... Paradigm Studio 20.. I also have a pair of... (0.00)
Posted by Eli Duttman on 2019-03-13, 01:16:14 (69.142.177.2)
I'd be inclined to connect both sets of speakers (only 1 set at a time) to the 4 Ω taps. Sacrifice some power in favor of good voice coil control. A Scott 299C or 299D should be just fine. Gettin .......
369: Radio Road, RE: Scott 4312 (0.00)
Posted by Eli Duttman on 2019-03-12, 16:22:13 (69.142.177.2)
Your imagination may not be playing tricks on you. The circuitry is quite interesting. While only the TRF front end and frequency conversion stages are tubed (nuvistors), the SS IF strip is transforme .......
370: Tubes Asylum, RE: I use the S5000 and switched out the 7199 (0.00)
Posted by Eli Duttman on 2019-03-12, 15:31:21 (69.142.177.2)
Any of the 6BL8/6GH8/6U8 group will work, without parts value changes and all 3 are pin compatible. If you check the Scott schematic archive , you will find clear evidence of the 3 types' interchangea .......
371: Tubes Asylum, RE: My speakers are 89db and top budget around 1k... (0.00)
Posted by Eli Duttman on 2019-03-12, 15:17:43 (69.142.177.2)
What is the nominal impedance of the speakers? Speaker manufacturers present their goods under a light that is not always truthful. For instance, 4 Ω nominal and 89 dB. sensitive with 2.83 V. of .......
372: Tubes Asylum, RE: Need advice on a tube amp.... (0.00)
Posted by Eli Duttman on 2019-03-12, 00:01:52 (69.142.177.2)
What speakers do you propose to use? Speakers and amp are "joined at the hip". If all your sources are "line" level, an amp with a pentode or cascode I/P stage can be combined with a passive control c .......
373: Tubes Asylum, RE: can't beat pair of China 12ax7 (0.00)
Posted by Eli Duttman on 2019-03-11, 09:21:30 (69.142.177.2)
Maybe, just maybe, the unit was carefully voiced around the Sino 'X7. However, I wouldn't bet on it. If an uncolored tube is to your liking, try the Sovtek 12AX7LPS. If you want top end energy, AKA "c .......
374: Tube DIY Asylum, RE: Best wishes - only one thing to say though (0.00)
Posted by Eli Duttman on 2019-03-11, 06:32:48 (69.142.177.2)
The gun is fine on Octal and UXn sockets, where the lugs are of good size. Having more than 1 iron is analogous to having several wrenches in a toolbox. .......
375: Tube DIY Asylum, RE: grid stoppers (0.00)
Posted by Eli Duttman on 2019-03-07, 11:47:41 (69.142.177.2)
The 5842 and 6C45Π (6s45p) are nasty. They "want" to oscillate just sitting in the cardboard box. In addition to stopper techniques on all grid connections, put a 100 Ω carbon film stopper o .......
376: Tubes Asylum, RE: 6922 Tubes (0.00)
Posted by Eli Duttman on 2019-03-05, 15:28:31 (69.142.177.2)
Amperex (Hicksville) was 1 of many plants and brands the Philips giant owned. A code was etched into the envelope to indicate which plant actually produced a particular specimen. Read this for the par .......
377: Tube DIY Asylum, RE: Sherwood S-5000 question (0.00)
Posted by Eli Duttman on 2019-03-04, 13:59:48 (69.142.177.2)
"Any ideas what other knobs might work on this amp, or suggestions of what I might do?" For the push buttons, have parts machined from aluminum. Nebraska Surplus has several "D" shaft knobs. Perhaps s .......
378: Tubes Asylum, RE: 6922 Tubes (0.00)
Posted by Eli Duttman on 2019-03-04, 13:26:11 (69.142.177.2)
A stock AI preamp is a "tube eater". None of the highly regarded NOS you suggested will last long. The 6DJ8/ECC88 is less tough than the 6922/E88CC and could fail in as little as 1 week. Hicksville, N .......
379: Tubes Asylum, RE: 6922 Tubes (0.00)
Posted by Eli Duttman on 2019-03-04, 09:31:14 (69.142.177.2)
Stock AI preamps are "tube eaters". :>(( The tube to use in a stock AI preamp is the Russian 6H23Π-EB (6n23p-ev). The ElectroHarmonix (EH) 6922 is, in fact, 6H23Π-EB. The only NOS variant, .......
380: Tubes Asylum, RE: No balance controls on the Pass (0.00)
Posted by Eli Duttman on 2019-03-03, 10:51:12 (69.142.177.2)
Like I said, tone controls totally out of the signal path, except in rare cases. No tone controls, whatsoever, is good too. PM me with the Pass' schematic. Adding a balance control to it, externally, .......
381: Tubes Asylum, RE: Stupid question about using a buffer with an integrated amp that already has a buffer (0.00)
Posted by Eli Duttman on 2019-03-02, 22:03:02 (69.142.177.2)
If at all possible, the signal should not go through 2 volume controls. Does the Pass buffer have a channel to channel balance adjustment capability? Tone controls help with surprisingly few recording .......
382: Tubes Asylum, RE: Stupid question about using a buffer with an integrated amp that already has a buffer (0.00)
Posted by Eli Duttman on 2019-03-02, 14:01:35 (69.142.177.2)
Expect some S/N degradation. Do you make use of the tape monitor loop? If not, a "simple" tweak will (IMO) do nicely. Repurpose the tape monitor switch and tape monitor jacks to switch the power secti .......
383: Vintage Asylum, RE: Recommended turntable for a Fidelity Research FR-24 (0.00)
Posted by Eli Duttman on 2019-02-27, 12:44:49 (69.142.177.2)
Don't forget cartridge ramifications. Based on the info. provided in previous posts, it seems like a Grado cart. would be a good mate for the arm. Grado carts. sound good, but are very susceptible to .......
384: Tube DIY Asylum, RE: Ever use the amp section, only? (0.00)
Posted by Eli Duttman on 2019-02-26, 12:53:40 (69.142.177.2)
Perhaps a tad too much closed loop gain is the only (IMO) legitimate criticism that can be made of the 222D's power section topology. Assuming you already own a unit, bring C23 and C123 out to a conve .......
385: Tube DIY Asylum, RE: Who has restored an HH Scott 222C? (0.00)
Posted by Eli Duttman on 2019-02-26, 07:16:07 (69.142.177.2)
"Need to source those 7199 tubes." Extinct, unobtainium, gone the way of the Dodo . Scott provides a solution to the problem. Use a pentode/triode that's still available. Refer to the 222D . FWIW, I f .......
386: Tube DIY Asylum, RE: Motor run rating (0.00)
Posted by Eli Duttman on 2019-02-25, 16:18:03 (69.142.177.2)
Just for the heck of it, I did a search and came up with this . That 400 VDC max. seems much firmer, now. BTW, the price of the linked part makes me wince . :>(( Guard the Aerovox parts on your "pile .......
387: Tube DIY Asylum, RE: I would not exceed 1.4x AC rating (0.00)
Posted by Eli Duttman on 2019-02-25, 10:59:53 (69.142.177.2)
Specific documentation would definitely help. FWIW, I've seen AC caps. whose DC ratings are > (2 1/2 )X the WVAC. A motor run cap. is carrying a time varying current of (sic) several A. It has to be c .......
388: Tube DIY Asylum, RE: NAD 1600 with itchy/scatchy volume pot (an FYI) 8^) (0.00)
Posted by Eli Duttman on 2019-02-16, 21:28:13 (69.142.177.2)
DeoxIT 5% on RCA connectors, not 100%. The solvent in 5% is naptha, AKA cigarette lighter fluid. Clean the 100% stuff off RCA connectors with naptha 1st, then follow with anhydrous isopropanol. ::: TO .......
389: Tubes Asylum, RE: Interesting. (0.00)
Posted by Eli Duttman on 2019-02-07, 00:54:19 (69.142.177.2)
This schematic shows the B+ being taken off pin 8. So, all would be well. Pin 8 is "lowest common denominator", when working with 5 V. vacuum rectifiers. Use of pin 8 is essential, when a cathode sle .......
390: Tubes Asylum, RE: Maybe, because they are very slow warm-up? (0.00)
Posted by Eli Duttman on 2019-02-06, 18:07:08 (69.142.177.2)
Aside from very slow warm up, another possible reason is taking the B+ off a CT on the 5 VAC winding. If a cathode sleeve is present, B+ has to be taken off pin 8. .......
391: Tube DIY Asylum, RE: Eli, he wants triode mode. (0.00)
Posted by Eli Duttman on 2019-02-01, 19:25:15 (69.142.177.2)
6 WPC is for triode wired. Move the g2 current limiting resistors from the plates to O/P "iron" UL taps and approx. 12 WPC is the yield. .......
392: Tube DIY Asylum, RE: PP 6AQ5 triode finals - output power potential ? (0.00)
Posted by Eli Duttman on 2019-02-01, 17:10:03 (69.142.177.2)
What are the biasing conditions? In "El Cheapo" the tubes operate in "shallow" Class "A" and cutoff occurs only at peak power O/P. Approx. 6 WPC are available. If you restrict yourself to true Class " .......
393: Tube DIY Asylum, RE: Oh, that's not good (0.00)
Posted by Eli Duttman on 2019-01-29, 08:27:33 (69.142.177.2)
If you want to tweak an existing unit, replace 1Nnnnn parts with the corresponding or higher PIV UFnnnn parts and rest easy. In practice, use UF4007s for 1 A. and UF5408s for 3 A. You may or may not r .......
394: Tube DIY Asylum, RE: UF4007 (0.00)
Posted by Eli Duttman on 2019-01-28, 11:49:46 (69.142.177.2)
The 7199 is "unobtainium". I like the Triode Electronics board, populated with 2X EF86s and an ECC99. Hafler's signal topology is retained, while using in production types whose performance exceeds th .......
395: Tube DIY Asylum, RE: "how can you resist the allure of a 1200v Schottky Wolfspeed/cree" (0.00)
Posted by Eli Duttman on 2019-01-28, 05:47:03 (69.142.177.2)
I agree with the use of high PIV Schottkys, in circuits designed for them, from the ground up. When you shoehorn in a TO220 case part as a replacement for a DO41 case part, you create an antenna for .......
396: Tube DIY Asylum, RE: Diodes (0.00)
Posted by Eli Duttman on 2019-01-27, 22:27:51 (69.142.177.2)
If the OP proceeds, he should use all UF4007s. Check the pricing. Higher PIV than necessary never hurts. Zero form factor issues in using UFnnnn parts. Noteworthy is previous post pointing out that a .......
397: Tube DIY Asylum, RE: Please check my diode choices (0.00)
Posted by Eli Duttman on 2019-01-27, 22:17:32 (69.142.177.2)
"but a lot of the benefit is produced by the psyche." Is that ever true. "Audiophillia Nervosa" strikes again. .......
398: Tube DIY Asylum, RE: RCA Phono Preamp (0.00)
Posted by Eli Duttman on 2019-01-22, 03:50:14 (69.142.177.2)
PJ, does what follows below contain the 6SC7 stuff you were discussing? As expected, grid leak biasing is employed. I see that same 5.6 K load found in the GE style setup. Presumably, that's what thos .......
399: Tube DIY Asylum, RE: RCA Phono Preamp (0.00)
Posted by Eli Duttman on 2019-01-21, 16:59:08 (69.142.177.2)
PJ, are you sure about the 6SC7? With its common cathode connection, the RCA design would be hard to execute. I have very vague recollections of the 6SL7 being mentioned as RCA's 1st tube in the passi .......
400: Tube DIY Asylum, RE: RCA Phono Preamp (0.00)
Posted by Eli Duttman on 2019-01-20, 19:42:20 (69.142.177.2)
"R1 has been changed from 2.2K to 2.4K." I hope that's a "typo". RCA's value is 22 Kohms and the change to 24 Kohms is well known. Give the post WW2 guys some credit. They got the job done with AC hea .......
401: Tube DIY Asylum, RE: Another Thought (0.00)
Posted by Eli Duttman on 2019-01-15, 22:15:33 (69.142.177.2)
"I don't know what effect the FET has in your phono stage except to lower the output impedance but whatever it is it makes great music." Lowering O/P impedance and providing decent drive capability is .......
402: Tube DIY Asylum, RE: Yellow "American Radiant" coupling caps (0.00)
Posted by Eli Duttman on 2019-01-14, 00:26:23 (69.142.177.2)
I have no firm knowledge. FWIW, I've seen that oval construction in metalized polypropylene more than once, but polyester can't be ruled out. Do those parts need replacement or do you like the "tone"? .......
403: Tube DIY Asylum, RE: Another Thought (0.00)
Posted by Eli Duttman on 2019-01-14, 00:14:44 (69.142.177.2)
Pretty darned good for working into 10 Kohms is a 4.7 μF. metalized polypropylene part bypassed by a 0.47 μF. 716P series "Orange Drop". I appreciate your "sand allergy", but do not share it .......
404: Tube DIY Asylum, RE: Russian Silver Tantalum Capacitors (0.00)
Posted by Eli Duttman on 2019-01-13, 19:23:48 (69.142.177.2)
This will help with pronunciation. T and O are "the same" in both Cyrillic and Latin. The character that resembles a "3" transliterates to "e". The string "суб." is an abbreviation .......
405: Tube DIY Asylum, RE: Another Thought (0.00)
Posted by Eli Duttman on 2019-01-13, 17:14:40 (69.142.177.2)
A plate loading choke is both costly and space consuming. A constant current source (CCS) is an excellent alternative to a choke. The properties of the CCS and O/P coupling cap. in the provided setup .......
406: Tube DIY Asylum, RE: Thanks for reminding me. (0.00)
Posted by Eli Duttman on 2019-01-12, 14:30:51 (69.142.177.2)
Perhaps the speaker enclosure is what you need to focus on. I'm thinking 2 small drivers and a single larger driver. Just feed the same I/P to both channels and use all 3 O/Ps in a manner similar to t .......
407: Tube DIY Asylum, RE: Need advice on a tube preamp for myself (0.00)
Posted by Eli Duttman on 2019-01-12, 14:10:41 (69.142.177.2)
Look up the VT60's spec's. What level of I/P signal is needed to obtain full power O/P from the VT60? Amplifying and then attenuating, to get overall gain structure right, has an adverse impact on S/N .......
408: Tube DIY Asylum, RE: So, 1 or 2 units? (0.00)
Posted by Eli Duttman on 2019-01-09, 20:02:05 (69.142.177.2)
1 or 2 is situation specific. Jim McShane uses 2X CL-150s, whose cold resistance is low. A single CL-90 or CL-140, where the cold resistance is substantial is fine. .......
409: Tube DIY Asylum, RE: "high voltage comes up slowly" That is a pretty relative term (0.00)
Posted by Eli Duttman on 2019-01-09, 17:57:15 (69.142.177.2)
The drop across a NTC device is small, when installed on the rectifier side. Yes, that 1/2 second isn't much in terms of signal tube emission starting. However, it's plenty for getting a SS rectified .......
410: Tube DIY Asylum, RE: Suggestions Please!!!!!!!!!!!!!!!!!!! (0.00)
Posted by Eli Duttman on 2019-01-09, 17:10:24 (69.142.177.2)
"Can you tell me a good quality lytic? And where to get it?" Remember Claude Rains in "Casablanca". "Round the usual suspects up." This part should get the job done. The schematic you provided shows .......
411: Tube DIY Asylum, RE: Suggestions Please!!!!!!!!!!!!!!!!!!! (0.00)
Posted by Eli Duttman on 2019-01-09, 06:13:10 (69.142.177.2)
Those DC link caps. have polypropylene film dielectric. Where they can occupy less room than a motor run is being constructed to function only under "DC" conditions. Motor run caps. have to be capable .......
412: Tube DIY Asylum, RE: Suggestions Please!!!!!!!!!!!!!!!!!!! (0.00)
Posted by Eli Duttman on 2019-01-08, 21:37:50 (69.142.177.2)
Perhaps a DC link cap. will need less room than a motor run. Check this part and this part out. If the DC link parts are no go, we'll look for a top notch 'lytic. .......
413: Tube DIY Asylum, RE: Staking Tools (0.00)
Posted by Eli Duttman on 2019-01-07, 17:00:48 (69.142.177.2)
Check the spec's for the provided anvils & punches, as to which size eyelets are supported. Mild steel is not going to be much better than brass, unless it's case hardened. A MAPP gas torch, "Cherry R .......
414: Tube DIY Asylum, Staking Tools (0.00)
Posted by Eli Duttman on 2019-01-07, 09:37:52 (69.142.177.2)
Would you kindly explain how you made staking tools? Would you consider making staking tools for and selling them to other "inmates"? BTW, a "basic staking kit" is not horribly expensive. .......
415: Vintage Asylum, RE: EL84's are probably the best sounding tube (0.00)
Posted by Eli Duttman on 2019-01-06, 15:55:16 (69.142.177.2)
The "12" W. multi-grid types, as a group, sound very good. Which is "best" may well depend on situation specifics. The 6V6 "clan" definitely makes a better triode than the 6BQ5/EL84. .......
416: Tubes Asylum, RE: I am not so sure (0.00)
Posted by Eli Duttman on 2019-01-03, 14:51:34 (69.142.177.2)
"Why it needed to go thru RCA is another mystery." IIRC, the tubes had to be sourced from a "U.S. company". Dutch giant Philips acquired Hicksville, NY, based Amperex to gain access to the huge Americ .......
417: Tube DIY Asylum, RE: Miller Effect (0.00)
Posted by Eli Duttman on 2019-01-02, 19:01:14 (69.142.177.2)
Operating conditions charts "A", "B", and "C" of the linked datasheet contain some interesting info. Consider a 33 Kohm EF86 plate load and a not so big succeeding stage grid to ground resistance. The .......
418: Tube DIY Asylum, RE: Variable UL Anyone? (0.00)
Posted by Eli Duttman on 2019-01-02, 16:59:18 (69.142.177.2)
"It's also annoying that you'll need that B++ supply, which will need to be a higher voltage than the B+ going to the output transformer." Many an amp has a FWCT rectified B+ supply. In a P2P wired un .......
419: Tube DIY Asylum, Durability? (nt) (0.00)
Posted by Eli Duttman on 2019-01-02, 14:20:47 (69.142.177.2)
.......
420: Tube DIY Asylum, RE: Miller Effect (0.00)
Posted by Eli Duttman on 2019-01-02, 14:19:47 (69.142.177.2)
"I just couldn't find a pentode with a voltage gain of 30." One moment, if you please. The Norton equivalent circuit for pentodes tells us that stage gain (α) is primarily a function of transcond .......
421: Tube DIY Asylum, RE: Alodine (0.00)
Posted by Eli Duttman on 2019-01-02, 13:55:53 (69.142.177.2)
Perhaps a solder "pad" technique is of use. Prepare a saturated solution of zinc sulfate and lower its pH by adding a small amount of sulfuric acid (auto battery acid is OK). Wherever you want conduct .......
422: Tube DIY Asylum, RE: The real reason I posted... (0.00)
Posted by Eli Duttman on 2019-01-01, 14:19:50 (69.142.177.2)
Except for some time, you have little to loose. Heat does drive moisture out of many materials. Bake the old CC parts and measure their values, following treatment. Check for noise too, while you are .......
423: Tube DIY Asylum, RE: Looking to build an EL-84 power amp (0.00)
Posted by Eli Duttman on 2018-12-30, 12:15:23 (69.142.177.2)
Your wish is my command. ;>) The "El Cheapo" signal topology works with the EL84/6BQ5, just fine. Only the resistance value in the RC O/P tube bias networks changes. The schematic shows triode mode wo .......
424: Vintage Asylum, Filter Choke and Space (0.00)
Posted by Eli Duttman on 2018-12-29, 20:24:51 (69.142.177.2)
Another look at the Scott 130 Schematic shows the B+ draw to be a mere 12.5 mA. That fact allows the selection of a physically "small" part of 15 H./20 mA., the Triad C-1X . Better filtering action + .......
425: Vintage Asylum, RE: Hum and Hiss Madness -Scott 130 Pre-amp (0.00)
Posted by Eli Duttman on 2018-12-28, 15:28:05 (69.142.177.2)
Make room for that choke! If necessary, use 'lytics till you get to the voltage take off positions. Performance wise, the Panasonic and Nichicon 105 o C. rated parts are nipping at film caps.' heels a .......
426: Tube DIY Asylum, RE: Wow, did I break the forum? (0.00)
Posted by Eli Duttman on 2018-12-28, 14:27:45 (69.142.177.2)
FWIW, I agree with the control grid spacing being a key factor. Another factor that might enter the calculus is the cathode's ability to emit electrons. Here too, the way g2 is set up seems irrelevant .......
427: Vintage Asylum, RE: Hum and Hiss Madness -Scott 130 Pre-amp (0.00)
Posted by Eli Duttman on 2018-12-28, 14:15:14 (69.142.177.2)
The choke immediately after the 1st filter cap. is key. Within reason, you can do just about anything that tickles your fancy, following a substantial inductance. $12.79 is Mouser's price for the C-8X .......
428: Vintage Asylum, RE: Hum and Hiss Madness -Scott 130 Pre-amp (0.00)
Posted by Eli Duttman on 2018-12-28, 13:55:28 (69.142.177.2)
35 μF. is definitely too big, for several reasons. You are increasing the ripple current and that increases I 2 R heating in the power trafo and may also be causing a 60 Hz. mechanical flex. Then .......
429: Tubes Asylum, RE: $24 for pair NOS GE rectifiers (0.00)
Posted by Eli Duttman on 2018-12-27, 23:29:23 (69.142.177.2)
$24 for a pair of GEs is a TERRIFIC deal and anybody who uses 5U4s should jump all over it. .......
430: Vintage Asylum, RE: Hum and Hiss Madness -Scott 130 Pre-amp (0.00)
Posted by Eli Duttman on 2018-12-27, 23:24:00 (69.142.177.2)
That Caig product is a great metal contact cleaner. However, it may not be great inside controls, where carbon tracks are to be found. This stuff is inexpensive enough to take a chance on. Another Ca .......
431: Tube DIY Asylum, RE: Help and recommendations for feedback in SE UL amp (0.00)
Posted by Eli Duttman on 2018-12-27, 21:40:56 (69.142.177.2)
"Tell me however, isn't this scheme about the same as simply having a large-ish unbypassed Rk for the output stage?" An unbypassed cathode resistor introduces degeneration, AKA local current NFB. Curr .......
432: Vintage Asylum, RE: Hum and Hiss Madness -Scott 130 Pre-amp (0.00)
Posted by Eli Duttman on 2018-12-27, 20:30:56 (69.142.177.2)
An appropriate spray cleaner into the controls is (IMO) worth a try. That stuff can easily go noisy. Another thing to look for is noise and/or drift in carbon composition resistors. Except for grid st .......
433: Tubes Asylum, RE: Or you could be boring. (0.00)
Posted by Eli Duttman on 2018-12-27, 19:15:16 (69.142.177.2)
There is nothing wrong with the GE cylindrical bottle tubes, but even they have begun to get somewhat pricey. Cash strapped folks will do just fine with the current production EH 5U4GB. What a world o .......
434: Tube DIY Asylum, RE: E88C (0.00)
Posted by Eli Duttman on 2018-12-27, 18:16:34 (69.142.177.2)
Yet another "in the box oscillator". A quick look suggests the type could be good in the 1st gain block of a phono preamp. Somebody better than me at the requisite computations can figure out what the .......
435: Tubes Asylum, RE: Anyone here tried the new KR RK 5U4G? (0.00)
Posted by Eli Duttman on 2018-12-27, 16:11:58 (69.142.177.2)
Uh, huh! Please folks, throw your money away in my direction. Instead of the "sexy" ST bottle tube, with its (IMO) silly price, buy the solid performing EH 5U4GB for about $18. 400 euros is "Emperor's .......
436: Tube DIY Asylum, RE: Help and recommendations for feedback in SE UL amp (0.00)
Posted by Eli Duttman on 2018-12-27, 15:01:36 (69.142.177.2)
Never, ever, put an interstage trafo inside a NFB loop. We just barely "sneak" by putting O/P "iron", with its low impedance secondary, inside NFB loops. I agree with your short, as opposed to global, .......
437: Tubes Asylum, RE: NOS 6189 and 12AT7 choices (0.00)
Posted by Eli Duttman on 2018-12-27, 07:24:46 (69.142.177.2)
A competent dealer knows his/her stock. Betcha Jim McShane can cull out phono grade tubes for you. Send him your unit's schematic and what your needs are. FWIW, I'm suspicious when "pushed" towards hi .......
438: Tube DIY Asylum, RE: Help and recommendations for feedback in SE UL amp (0.00)
Posted by Eli Duttman on 2018-12-26, 19:58:42 (69.142.177.2)
OK, 10 Ω between cathode and ground. Try 100 Ω between the O/P trafo's secondary and the junction of the 10 Ω part and the cathode. The voltage divider formed feeds approx. 9% of the O/ .......
439: Tube DIY Asylum, RE: Help and recommendations for feedback in SE UL amp (0.00)
Posted by Eli Duttman on 2018-12-26, 18:32:10 (69.142.177.2)
Consider inverting the phasing of the O/P trafo secondary. Then, you can apply the NFB to the low impedance cathode circuitry of U2. Don't worry about the tiny amount of resistance between U2's cathod .......
440: Vintage Asylum, RE: "best not to use a 50 year old cap in the coupling position for output tubes" (0.00)
Posted by Eli Duttman on 2018-12-26, 18:12:32 (69.142.177.2)
PIO stands up to time IF it's hermetically sealed. For all the hoopla about how great they sound, pass PIO caps. of any "vintage" by, when they lack hermetic sealing. Highly regarded Vit. Q and K40 ca .......
441: Tubes Asylum, RE: NOS 6189 and 12AT7 choices (0.00)
Posted by Eli Duttman on 2018-12-26, 16:56:01 (69.142.177.2)
What can "rolling" the rectifier do, other than possibly alter the rail voltage? The answer is nothing and no change is possible, if both specimens closely adhere to the specifications for the type. I .......
442: Tube DIY Asylum, RE: Amp circuit? Plate impedance calculation. (0.00)
Posted by Eli Duttman on 2018-12-26, 13:40:51 (69.142.177.2)
There's more than 1 way to get a good estimate of the needed value. FWIW, I do a voltage swing analysis working backwards from the speaker. The key facts are P = V 2 /R and the impedance ratio of a tr .......
443: Tube DIY Asylum, RE: 5842 for transconductance NT (0.00)
Posted by Eli Duttman on 2018-12-25, 20:15:44 (69.142.177.2)
In the same vein is the Russian 6C45Π (6s45p). Both the 6C45Π and the 5842 require extraordinary measures to suppress parasitic oscillation be taken, when operated common cathode. These ty .......
444: Tubes Asylum, RE: Many , many, direct substitutes (0.00)
Posted by Eli Duttman on 2018-12-25, 15:42:46 (69.142.177.2)
"Any opinion on Mullard, RCA, Brimar?" All excellent. Which is "best" is situation dependent. One size does not fit all. At $10.50 per tube, the current production JJ 12AT7 is definitely worth a try. .......
445: Tubes Asylum, RE: NOS 6189 and 12AT7 choices (0.00)
Posted by Eli Duttman on 2018-12-25, 15:27:33 (69.142.177.2)
12AT7WA & 12AT7WB black plates. Sometimes, they'll be labeled 6201. .......
446: Tubes Asylum, RE: NOS 6189 and 12AT7 choices (0.00)
Posted by Eli Duttman on 2018-12-25, 14:14:30 (69.142.177.2)
RCA black plates, for starters. They are expensive. .......
447: Tubes Asylum, RE: Many , many, direct substitutes (0.00)
Posted by Eli Duttman on 2018-12-25, 14:11:39 (69.142.177.2)
The Philips 12AT7WC is an "OK" audio tube, but there are all sorts of better sounding 12AT7 variants. Even the current production JJ might surprise you. NOS Mullard CV4024s are nice, without carrying .......
448: Tube DIY Asylum, Please PM Me (nt) (0.00)
Posted by Eli Duttman on 2018-12-25, 13:23:36 (69.142.177.2)
.......
449: Tube DIY Asylum, RE: modern volume pot for Pilot Sp-210 (0.00)
Posted by Eli Duttman on 2018-12-25, 12:20:57 (69.142.177.2)
Look at the SP-210 schematic. Electrically atrocious is spot on! The O/Ps, both recording and line, have zero drive capability. The high grid to ground resistances in combination with the 'X7 triode' .......
450: Tubes Asylum, RE: Pilot 240 rectifier question (0.00)
Posted by Eli Duttman on 2018-12-24, 20:44:03 (69.142.177.2)
Yes, the datasheet shows 60 μF. as the max. for a cap. I/P filter. However, notice the resistance requirements given. Yes, JJ's Octal production leaves quite a bit to be desired. IMO, the afford .......
451: Tube DIY Asylum, RE: Yes, only need 9-pin (0.00)
Posted by Eli Duttman on 2018-12-24, 11:38:28 (69.142.177.2)
Wire the channels asymmetrically to use only 1/2 of a twin triode. When wear becomes evident, flip/flop the tubes and get doubled service life. .......
452: Tube DIY Asylum, RE: Type CL thermistors (0.00)
Posted by Eli Duttman on 2018-12-22, 16:49:03 (69.142.177.2)
A negative voltage applied to the grid provides electrostatic shielding of the cathode, cold or hot, from the influence of a positively charged plate. Whether or not cathode stripping and/or ion bomba .......
453: Tube DIY Asylum, RE: Type CL thermistors (0.00)
Posted by Eli Duttman on 2018-12-21, 11:44:00 (69.142.177.2)
The last thing you want is a delay in bias supply start. Whether or not protection is needed is a matter for discussion, but there is no electrostatic protection unless bias supply start is "instant .......
454: Tube DIY Asylum, RE: Type CL thermistors (0.00)
Posted by Eli Duttman on 2018-12-21, 06:30:15 (69.142.177.2)
That's not entirely correct. Each of the various types has a time constant. Some of those constants are substantial. A link to the data sheet is provided below Placement on the secondary side can be a .......
455: Vintage Asylum, RE: Receiver vintage (0.00)
Posted by Eli Duttman on 2018-12-20, 08:44:05 (69.142.177.2)
Can you solder? If yes, look into the Sansui n0n0 receiver line. The weak link in otherwise excellent products is the wire wrap connections. Soldering those corrects things. FWIW, I used to own a 7070 .......
456: Vintage Asylum, RE: Focal 12-inch, 4-ohm? (0.00)
Posted by Eli Duttman on 2018-12-18, 14:25:01 (69.142.177.2)
I'll add the usual caveat about dealing with 4 Ω drivers. Derate the claimed sensitivity by 3 dB., as 2.83 V. into 4 Ω is 2 W., not 1 W. Manufacturers cast themselves in the most favorable .......
457: Vintage Asylum, RE: Heathkit (0.00)
Posted by Eli Duttman on 2018-12-18, 09:11:17 (69.142.177.2)
That TubeStore price is attractive, but there's the issue of power pentode matching. There (naturally) will be a charge for that service and there's also the need for each tube in a set of 4 (2X match .......
458: Vintage Asylum, RE: Upgrade? (0.00)
Posted by Eli Duttman on 2018-12-17, 20:58:23 (69.142.177.2)
Look here . It's got an AC motor. IMO/IME, a Grado cart. is a bad idea. Look up and down Audio Technica's MM line. There are models for every budget. This "reasonably priced" Ortofon , with an ellipt .......
459: Vintage Asylum, RE: Heathkit (0.00)
Posted by Eli Duttman on 2018-12-17, 09:22:07 (69.142.177.2)
Converting to EL84s requires abandoning the tone controls and (potentially) the phono section too. Reworking the unit to use PCL86s instead of ECL86s as "finals" allows the signal topology, including .......
460: Vintage Asylum, RE: Heathkit (0.00)
Posted by Eli Duttman on 2018-12-16, 07:55:13 (69.142.177.2)
To keep the tone controls going, buy either 2 or 4 matched PCL86 pairs here and wire the heaters in series. A 36 Ω resistor goes at each end of the series string. Power the composite with a Triad .......
461: Vintage Asylum, RE: Upgrade? (0.00)
Posted by Eli Duttman on 2018-12-16, 07:02:40 (69.142.177.2)
An Audio Technica AT440MLB is a safe, reasonably high performance MM cartridge selection. Not knowing about your TT's motor makes Grado a dubious recommendation, as unshielded AC motors hum (yuck!) in .......
462: Vintage Asylum, RE: Heathkit (0.00)
Posted by Eli Duttman on 2018-12-16, 06:42:10 (69.142.177.2)
You sure can put a stand alone SUT between the Denon 103 and the AA-32. Use the mag. phono jacks and source selector position. .......
463: Tube DIY Asylum, RE: Opinions on Tonal Qualities - 6P3S Pentode/Triode VS 6V6? (0.00)
Posted by Eli Duttman on 2018-12-15, 10:18:16 (69.142.177.2)
The current production "reissue" TungSol 6V6 is very good and is priced favorably vs. NOS. FWIW, "Poindexter" is on record in preferring the "reissue" to the remaining OS stock. .......
464: Vintage Asylum, RE: Heathkit (0.00)
Posted by Eli Duttman on 2018-12-15, 05:12:01 (69.142.177.2)
Are you using the phono section? That portion of the unit employs RCA's famous passive EQ topology. .......
465: Vintage Asylum, RE: Heathkit (0.00)
Posted by Eli Duttman on 2018-12-15, 04:53:40 (69.142.177.2)
I agree with the system synergy concept. It's an effing shame that a supply of 6GW8 replacements is not available. .......
466: Vintage Asylum, RE: Upgrade? (0.00)
Posted by Eli Duttman on 2018-12-14, 16:53:52 (69.142.177.2)
SS B+ rectification is OEM. Replacement of the OEM diodes with UF4007s is inexpensive and rates to help a little. Don't get overly enthusiastic about increasing PSU capacitance, lest power trafo overh .......
467: Tubes Asylum, RE: 6Z5 family? (n/t) (0.00)
Posted by Eli Duttman on 2018-12-14, 13:36:19 (69.142.177.2)
I believe that's UX6 based, as is the similar 6Y5. I'm early in the "scheming & plotting" stage of another exploitation of Pete Millett's 2 rails from 1 CT winding concept. This time around, I've come .......
468: Tubes Asylum, RE: Rectifier Question (0.00)
Posted by Eli Duttman on 2018-12-14, 12:58:00 (69.142.177.2)
The Bendix 6754 is another, very interesting, "Red Bank" brute. 80,000 feet, sheesh! However, being 100 mA. capable, it's overkill for the job I have in mind. Then, there's the price. :>( I could see .......
469: Tube DIY Asylum, RE: Component Performance (0.00)
Posted by Eli Duttman on 2018-12-14, 03:35:17 (69.142.177.2)
Yet more info. as to how bad a pile of RANK male bovine dung the RoHS directive banning leaded solder is. :>(( Egotistical bureaucrats combined with bad science yields highly unpleasant consequences. .......
470: Tubes Asylum, Rectifier Question (0.00)
Posted by Eli Duttman on 2018-12-13, 16:54:09 (69.142.177.2)
Is anyone aware of a "6" V., indirectly heated, full wave vacuum rectifier whose current capability is greater than a 6AL5's and less than a 6X4's? .......
471: Tube DIY Asylum, RE: Russian Tubes (0.00)
Posted by Eli Duttman on 2018-12-08, 09:55:43 (69.142.177.2)
A lot of the time, AC energized heaters are made positive with respect to the cathode and those data sheets you mentioned may simply be an oversimplification. I'm inclined to respect the Russian datas .......
472: Tube DIY Asylum, RE: Cathode Followers & Non-Elevated Heaters (0.00)
Posted by Eli Duttman on 2018-12-08, 02:41:30 (69.142.177.2)
JJ's ECC99 heater to cathode rating is 200 V. and the high gm makes the type especially well suited to voltage follower service. FWIW, this type seems to be 1 of Jamona's better efforts. .......
473: Tubes Asylum, RE: series filaments on doides? (0.00)
Posted by Eli Duttman on 2018-12-07, 16:40:30 (69.142.177.2)
Yes, you can do it. Take the B+ off the junction of the 2 filaments. .......
474: Tubes Asylum, RE: Motorola 12AT7-8M tubes (0.00)
Posted by Eli Duttman on 2018-12-07, 02:26:52 (69.142.177.2)
T/K, do you happen to know if Motorola actually manufactured those tubes or if they were contracted out? As has been said, "Not my area of expertise". .......
475: Tubes Asylum, RE: How's your German?.... (0.00)
Posted by Eli Duttman on 2018-12-05, 20:10:15 (69.142.177.2)
The website is Czech. The verbiage is German. Kaufen = purchase. FWIW, I read "nicht auf Lager" as not in stock and that's in accord with the 2 week average delivery delay. Look here for exchange rate .......
476: Tube DIY Asylum, RE: Recommend A Quality 100K Volume Pot (0.00)
Posted by Eli Duttman on 2018-12-03, 13:03:02 (69.142.177.2)
This should work for you. Hot molded carbon is "warmer" than conductive plastic. .......
477: Tubes Asylum, You Have Mail! (nt) (0.00)
Posted by Eli Duttman on 2018-12-03, 11:47:29 (69.142.177.2)
.......
478: Tubes Asylum, RE: Which 6CA7 or EL34? (0.00)
Posted by Eli Duttman on 2018-12-03, 09:45:43 (69.142.177.2)
I loathe "Cheap Charlie" DC heaters. The audio signal modulates the preamp tubes' heater current, which (in turn) varies cathode emission. :>(( Building a regulated 12 VDC supply for the preamp tubes .......
479: Tubes Asylum, RE: You have close-up photo? (0.00)
Posted by Eli Duttman on 2018-12-03, 00:24:54 (69.142.177.2)
Perhaps this at McMaster/Carr will help. Looks like 3 wire, 18 AWG, with PVC insulation. BTW, by itself, PVC is quite rigid. PVC is made flexible by the addition of "plasticizers", like dioctyl phthal .......
480: Tubes Asylum, RE: Which 6CA7 or EL34? (0.00)
Posted by Eli Duttman on 2018-12-01, 07:47:37 (69.142.177.2)
Talk to Jim McShane about "reissue" KT77s. The Jamona plant knows how to make good tubes. Having the will to do so is another matter. When correctly made, Jamona's E34L is fine. WHEN CORRECTLY MADE. : .......
481: Tube DIY Asylum, RE: switch on B+ (0.00)
Posted by Eli Duttman on 2018-12-01, 00:51:59 (69.142.177.2)
FWIW, I like inrush current limiters with either SS or directly heated vacuum rectifiers between the diodes and the PSU filter, not on the primary side. That way, any bias supply that's present turns .......
482: Vintage Asylum, RE: Toshiba DVD players SD-3960 & 4960 (0.00)
Posted by Eli Duttman on 2018-11-30, 21:38:35 (69.142.177.2)
Farnell owned both MCM and Newark. They've been merged under (AFAIK) Farnell's control. .......
483: Tubes Asylum, RE: If talking dissipation in watts... The 807 is 25 watts as well.-nt (0.00)
Posted by Eli Duttman on 2018-11-26, 16:49:11 (69.142.177.2)
Be careful about "apples and oranges" and watch out for different rating systems. Notice the 807 datasheet speaks about things like CCS (continuous commercial service) & ICAS (intermittent commercial .......
484: Tube DIY Asylum, RE: Is a switch on B+ adding noise? And 5.95VDC on heaters (0.00)
Posted by Eli Duttman on 2018-11-26, 12:20:55 (69.142.177.2)
5.95 V. is well within 10%, on the low side. There is no problem. A 6CA4 has a cathode sleeve and B+ rises slowly. A switch is totally unnecessary. .......
485: Vintage Asylum, RE: Fisher Ident and Weird Label (0.00)
Posted by Eli Duttman on 2018-11-26, 12:07:22 (69.142.177.2)
That's not the series tweak. Notice that both SS diodes' cathodes are tied to pin 8, the B+ take off point. Follow the series tweak diagram I provided using new UF4007s. I can't say that Fisher's X-10 .......
486: Tube DIY Asylum, RE: opinions sought re: 2A3 variants 6A3, 6B4G etc (0.00)
Posted by Eli Duttman on 2018-11-26, 07:43:19 (69.142.177.2)
To run SE, the "6" V. types need current regulated DC heating. The higher the filament voltage, the more hum prone a DH type is, when heated with AC. .......
487: Tube DIY Asylum, RE: It is Antek AS-05T240 (0.00)
Posted by Eli Duttman on 2018-11-26, 04:19:11 (69.142.177.2)
Yes, that model is bridge rectification only. NBD, as hybrid bridges work very well and are dominated by the vacuum rectifier. .......
488: Tube DIY Asylum, RE: The toroidal trans has no center tap. Problem? (0.00)
Posted by Eli Duttman on 2018-11-26, 02:56:45 (69.142.177.2)
Yes, you have to use a hybrid bridge rectifier. Obviously, the voltage of the winding being rectified has to be correct. You use SS diodes to form the connection to ground. UF4007s snubbed by 0.01 .......
489: Tube DIY Asylum, RE: Question about adapting 6V transf to 5V rectifier operation (0.00)
Posted by Eli Duttman on 2018-11-25, 19:37:45 (69.142.177.2)
Like its "big brother", the 5AR4/GZ34, the 6CA4/EZ81 is (for a vacuum rectifier) unusually tolerant of significant capacitance at the PSU filter's I/P. A 6CA4 can tolerate up to 50 μF. ::: TOPIC: .......
490: Tubes Asylum, RE: What is the electrical equivalent to the KT66 (0.00)
Posted by Eli Duttman on 2018-11-25, 19:27:32 (69.142.177.2)
As I understand the history , GEC/MOV was working on things and handed development off to RCA (money talks ...). In 1936, RCA came out with the 1st practical beam power tetrode, the metal envelope 6L6 .......
491: Vintage Asylum, RE: Fisher Ident and Weird Label (0.00)
Posted by Eli Duttman on 2018-11-25, 13:21:47 (69.142.177.2)
The "Cheap Charlie" method for DC heaters uses the small signal tube heaters as part of the O/P tube's bias network. IMO, "Cheap Charlie" is fugly, as the music signal modulates the heater current. :> .......
492: Tube DIY Asylum, RE: I want to construct a simple(?) phono preamp... (0.00)
Posted by Eli Duttman on 2018-11-25, 07:16:29 (69.142.177.2)
The 12AU7 is OUT, as it lacks gain, is non-linear, and is too noisy. The 12AX7 is acceptable, but it has next to no drive capability. The tweaked RCA setup I've provided has a MOSFET buffer that dispo .......
493: Vintage Asylum, RE: Fisher Ident and Weird Label (0.00)
Posted by Eli Duttman on 2018-11-24, 09:12:08 (69.142.177.2)
Fisher phono sections have a reputation for mediocre bass extension. FWIW, I suggest you consider the tweaked RCA setup as the replacement. The MOSFET buffer allows "dubbing" of LPs, without fear of i .......
494: Tube DIY Asylum, RE: Heater Elevation (0.00)
Posted by Eli Duttman on 2018-11-20, 20:12:13 (69.142.177.2)
C1 is an AC connection to ground for hum and (possibly) other "nasties". .......
495: Tubes Asylum, RE: Why did they make 7 volt tubes? (0.00)
Posted by Eli Duttman on 2018-11-20, 16:55:49 (69.142.177.2)
As Steve O stated, the P--- & U--- European types are for series heater string service. P = 300 mA., while U = 100 mA. .......
496: Tubes Asylum, RE: 7DJ8 Telefunkens (0.00)
Posted by Eli Duttman on 2018-11-19, 18:34:19 (69.142.177.2)
Yes, the heater is running cold, which reduces emission and lowers gm. Square peg in round hole = bad idea. To hear what that TFK PCC88 is really capable of, run it off a current regulated 300 mA. sup .......
497: Tubes Asylum, RE: 6SN7 why no love? (0.00)
Posted by Eli Duttman on 2018-11-15, 09:52:23 (69.142.177.2)
Perhaps size. Also, until fairly recently, decent current production tubes were not available. The "reissue" TungSol is quite decent. If you DIY, you can try the provided hybrid setup. It's VERY linea .......
498: Tube DIY Asylum, RE: New Use for Deoxit (?) (0.00)
Posted by Eli Duttman on 2018-11-10, 22:51:35 (69.142.177.2)
There's rosin and there's rosin. RA (rosin activated) contains a bit of zinc chloride, a Lewis acid of sorts. FWIW, I bought 63/37 SnPb RA flux core for "non-critical" jobs. Careful cleanup after use .......
499: Tube DIY Asylum, RE: filament trans question (0.00)
Posted by Eli Duttman on 2018-11-10, 16:39:07 (69.142.177.2)
V = IR 1/2 the current = twice the resistance. So, the individual resistors are 800 Ω/10 W. .......
500: Tube DIY Asylum, RE: New Use for Deoxit (?) (0.00)
Posted by Eli Duttman on 2018-11-10, 16:34:01 (69.142.177.2)
That makes perfect sense. The oleic acid in DeoxIT "cuts" metal oxides and sulfides. TK, what sort of flux is associated with the solder you're using? No clean has obvious benefits around PCBs, but go .......
Found total of 500 records, Query: , Author: Eli Duttman in All Forums, Time: 3 sec.