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1: Tube DIY Asylum, Magic Box (0.00)
Posted by MikeT on 2009-09-17, 13:36:33 (135.245.10.5)
Go here to see the magic box: http://www.nutshellhifi.com/VSAC2003.html Scroll down the page until you get to the part about Allen Wright. Cheers Mike .......
2: Tube DIY Asylum, LSES Forum Needed (0.00)
Posted by MikeT on 2008-10-06, 07:49:45 (198.205.32.90)
I think we need an LSES forum. Anyone else agree? .......
3: Tube DIY Asylum, Schematic of Properly Designed Amp (0.00)
Posted by MikeT on 2008-09-03, 07:37:33 (198.205.32.91)
Can you post a schematic of a properly designed 300B amp? .......
4: Tube DIY Asylum, JJ 300B Quality and Reliability? (0.00)
Posted by MikeT on 2008-09-02, 16:25:45 (63.249.44.17)
Anyone have any issues with JJ 300B quality and/or reliability? .......
5: Tube DIY Asylum, 6CJ3 (nt) (0.00)
Posted by MikeT on 2008-09-02, 10:41:05 (198.205.32.91)
nt .......
6: Bottlehead Forum, Pot on Paramount (0.00)
Posted by MikeT on 2008-08-14, 15:04:16 (198.205.32.91)
What's the pot for on the Paramount? Hum balance? .......
7: SET Asylum, RE: Update (08/07/08) (0.00)
Posted by MikeT on 2008-08-07, 11:53:56 (198.205.32.96)
I'm not familiar with the 5965. I have usually use the 6CG7 in preamps and I like the way they sound. .......
8: SET Asylum, RE: Update (08/07/08) (0.00)
Posted by MikeT on 2008-08-07, 11:14:33 (198.205.32.96)
I would use a 6CG7 over a 12AU7. the 6CG7 has plate curves identical to the 6SN7. .......
9: Tube DIY Asylum, RE: 2A3 Class A Push Pull project.... (0.00)
Posted by MikeT on 2008-05-31, 19:05:52 (63.249.44.17)
I built a PP 2A3 amp a few years ago: First stage 5687 LTP with CCS tail load Second stage 5687 Diff Amp with CCS tail load Shunt volume control to the grid of the first stage ST-70 OPTs B+ was about .......
10: Tube DIY Asylum, RE: Well, here's what I've learned... (0.00)
Posted by MikeT on 2008-04-03, 14:49:01 (143.209.103.3)
If you leave, then the idiots win. The rest of us don't get the benefit of your shared knowledge. I say, stay, and fight the ignorance! .......
11: Tube DIY Asylum, I Use a Sub Too (0.00)
Posted by MikeT on 2008-01-31, 19:49:45 (63.249.44.17)
I also feed an M&K sub. I have Fostex FE103 speakers and use the sub to fill in the bottom. It took me a while to integrate the speakers but I've got the levels dialed in and things sound pretty good. .......
12: Tube DIY Asylum, Looks Great - I Took a Different Route (0.00)
Posted by MikeT on 2008-01-31, 19:16:35 (63.249.44.17)
My amp is 5687>5687>6550/KT88 triode strapped. I also use the BFT-1B - a manly hunk of iron! Shunt volume control, CLCLC FW supply with 6CJ3 damper diodes gives me a B+ of around 500V. DC filaments. J .......
13: Tube DIY Asylum, RE: Got my GE 6550As - Thanks Jim McShane (0.00)
Posted by MikeT on 2008-01-31, 17:15:12 (63.249.44.17)
What's your operating point? .......
14: Tube DIY Asylum, www.tubesandmore.com (nt) (0.00)
Posted by MikeT on 2008-01-16, 12:13:51 (143.209.103.3)
.......
15: Tube DIY Asylum, What Happens When a PS Choke Saturates? (0.00)
Posted by MikeT on 2008-01-03, 13:20:57 (143.209.101.94)
Does it become a dead short? .......
16: Digital Drive, RE: Opus DAC listening impressions (0.00)
Posted by MikeT on 2007-12-05, 13:05:37 (143.209.101.94)
It was me who asked. Thanks for the report. Mike .......
17: Bottlehead Forum, Thanks (nt) (0.00)
Posted by MikeT on 2007-11-30, 10:54:47 (143.209.101.94)
.......
18: Bottlehead Forum, DC Filament Supply Using FC-1 (0.00)
Posted by MikeT on 2007-11-29, 10:45:37 (143.209.101.94)
Can someone post of schematic of a DC filament supply for a 300B using the FC-1? Thanks .......
19: Tube DIY Asylum, Modern 5AR4 Reliability (0.00)
Posted by MikeT on 2007-11-25, 12:57:49 (63.249.44.17)
Which modern 5AR4 (JJ, Russian, Chinese) is most reliable? .......
20: Digital Drive, RE: Opus DAC (0.00)
Posted by MikeT on 2007-11-07, 13:47:35 (143.209.101.94)
Thanks. Please let me know how it turns out. .......
21: Digital Drive, Opus DAC (0.00)
Posted by MikeT on 2007-11-04, 13:39:42 (63.249.44.17)
Anyone have an Opus DAC? How does it sound? .......
22: Bottlehead Forum, I Don't Have A Scope (nt) (0.00)
Posted by MikeT on 2006-02-22, 04:39:06 (63.249.44.17)
.......
23: Bottlehead Forum, Excellent Info! (0.00)
Posted by MikeT on 2006-02-20, 11:51:57 (192.160.6.252)
Thanks for the great information. Just what I needed! Mike T. .......
24: Bottlehead Forum, Some Q's About UF4007 Rectification (0.00)
Posted by MikeT on 2006-02-18, 08:26:25 (63.249.44.17)
You guys have more experience with UF4007's than anyone. I've got some questions about SS rectification. For a full wave rectifier configuration, how do I install a RRSF? If someone can point me to a .......
25: Bottlehead Forum, Cathode Stripping (0.00)
Posted by MikeT on 2005-12-18, 10:42:06 (63.249.44.17)
Is cathode stripping a practical concern? I notice a lot of solid state recitified amps are out there. Does slamming a cold DHT with B+ shorten it's life to an appreciable degree? .......
26: Tube DIY Asylum, Now I'm Confused - But Not By You Guys! (0.00)
Posted by MikeT on 2005-12-10, 20:03:15 (63.249.44.17)
I agree with what both of you have written. Let's assume I drive the output stage with +/- 45V. The current swing of the output stage is then close to +/-60 ma. I thought this would work because I've .......
27: Tube DIY Asylum, Re: 0D3 Won't Light - Any Ideas? (0.00)
Posted by MikeT on 2005-12-10, 08:23:49 (63.249.44.17)
Thanks Joel. I figured with a Class A amp the regulation would be OK, since the load is fairly constant. I suppose I can achieve good regulation if I go LCLC. .......
28: Tube DIY Asylum, 0D3 Won't Light - Any Ideas? (0.00)
Posted by MikeT on 2005-12-10, 07:33:50 (63.249.44.17)
I'm running two 0D3's in series to give me 300V. The load is 174 ma. The current limiting resistor is 260 ohms. The B+ is 358 V. the voltage across the resistor is 50V, which gives me a current draw o .......
29: Tube DIY Asylum, Whitlock Noise Presentation (0.00)
Posted by MikeT on 2005-08-13, 20:33:32 (63.249.44.17)
There is a pretty big difference between the neutral and safety ground. Bill Whitlock of Jensen Transformers explains it very well in the presentation. .......
30: Bottlehead Forum, Amen To That..... (0.00)
Posted by MikeT on 2005-08-04, 14:32:23 (192.160.6.252)
I got my start in Tube DIY by building a Foreplay. the price what right and I learned a heck of a lot about construction techniques. There's no telling how much solder I've slinged since then. Thanks .......
31: MagneQuest/Peerless Forum, They Do Indeed....... (0.00)
Posted by MikeT on 2005-08-04, 14:27:02 (192.160.6.252)
.... I was hoping for source for a less expensive "knock off." .......
32: Tube DIY Asylum, What Brought This On? (0.00)
Posted by MikeT on 2005-08-02, 18:05:58 (63.249.44.17)
I'm smiling as I'm typing. Did someone jump all over you? I agree with what you write. Engineering is like every other profession. It takes years of study and the degrees to prove it. It's possible t .......
33: SET Asylum, Love The Quote..... (0.00)
Posted by MikeT on 2005-07-31, 14:41:14 (63.249.44.17)
Laugh while you can, monkey boy. .......
34: MagneQuest/Peerless Forum, Where Did You Get The Tube Sockets? (nt) (0.00)
Posted by MikeT on 2005-07-31, 13:41:18 (192.160.6.253)
.......
35: Welborne Labs, I Second That (nt) (0.00)
Posted by MikeT on 2005-07-29, 11:07:40 (192.160.6.252)
.......
36: Bottlehead Forum, One More Question...... (0.00)
Posted by MikeT on 2005-07-28, 14:57:05 (192.160.6.253)
Thanks Paul. How do you compare gapped SE and parafeed? I'm sure you guys did extensive experimentation, so you must have settled on parafeed for good reason. The iron is expensive either way, so I'm .......
37: Bottlehead Forum, Slighty OT: Parafeed ST70 OPT's? (0.00)
Posted by MikeT on 2005-07-28, 13:43:43 (63.249.44.17)
Since this is SE parafeed central, how do you guys think a parafeed ST-70 OPT would sound, driven by either a 2A3 or 300B? I have a pair of A470's with cloth leads. Would a standard SE OPT be better? .......
38: Welborne Labs, Re: This forum will self distruct in 5 minutes (0.00)
Posted by MikeT on 2005-07-28, 13:34:59 (63.249.44.17)
Postings seem to be way down on all the tube-related forums. I've been a member of AA for four years and it seems things have really fallen off on Tube DIY, SET, KandK, and Welborne. My impression is .......
39: Tube DIY Asylum, Re: Push pull 3k or 4k transformers - Dynaco Acro Lundahl anyone? (0.00)
Posted by MikeT on 2005-07-22, 20:52:15 (63.249.44.17)
I have a pair of Dynaco A470's I'll sell if the price is right. I'll send you an email. .......
40: Propeller Head Plaza, Re: 150 db? (0.00)
Posted by MikeT on 2005-07-15, 12:58:31 (192.160.6.252)
What's the power supply noise level in your test equipment? .......
41: Tube DIY Asylum, How About Muting? (0.00)
Posted by MikeT on 2005-07-15, 11:59:25 (192.160.6.252)
I'm torn by muting circuits. I once modded an SCD-CE775 to remove all the clap trap in the output stage (LPF, muting circuit, in-line electrolytic coupling cap, etc.). I simply ran with an OPA2134 buf .......
42: Propeller Head Plaza, Re: 150 db? (0.00)
Posted by MikeT on 2005-07-14, 13:10:49 (192.160.6.252)
I don't know the reference level, I copied the quote exactly. I'm trying to determine if I should spend the bucks on Black Gates, or if the claims are BS. .......
43: Propeller Head Plaza, 150 db? (0.00)
Posted by MikeT on 2005-07-14, 10:54:46 (192.160.6.252)
Here is a claim by Black Gate capacitors: "Developed based on the Successfully eliminated in distortion and also nonlinear distortion which is inevitable with conventional polarized electrolyte capaci .......
44: SET Asylum, I Did No Responses (nt) (0.00)
Posted by MikeT on 2005-07-11, 20:37:45 (63.249.44.17)
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45: SET Asylum, Anyone Have Experience with Lundahl SE OPT'S? (0.00)
Posted by MikeT on 2005-07-11, 17:24:37 (63.249.44.17)
I'm thinking about 1664 or 1623 SE. Can anyone share their experiences with Lundahl SE iron? .......
46: Tube DIY Asylum, Allied Electronics Has Them (0.00)
Posted by MikeT on 2005-07-10, 16:31:28 (63.249.44.17)
See link..... .......
47: K&K Audio / Lundahl Transformers, Anyone Have Experience with Lundahl SE OPT'S? (0.00)
Posted by MikeT on 2005-07-07, 10:38:11 (63.249.44.17)
I'm thinking about 1664 or 1623 SE. Can anyone share their experiences with Lundahl SE iron? .......
48: Welborne Labs, DRD Amp OPT's (0.00)
Posted by MikeT on 2005-06-26, 08:04:48 (63.249.44.17)
Which Electra-Print OPT does the DRD use? .......
49: Welborne Labs, Removed From the Ads (0.00)
Posted by MikeT on 2005-06-24, 09:51:42 (192.160.6.252)
I removed the equipment from the ads. No reasonable offers made. I'm going another route. .......
50: Tube DIY Asylum, Schematic Drawing Package? (0.00)
Posted by MikeT on 2005-06-10, 14:36:20 (192.160.6.253)
Russ, what package did you use to draw your schematic? .......
51: Tube DIY Asylum, Check Out This Link (0.00)
Posted by MikeT on 2005-06-10, 13:50:21 (192.160.6.253)
Carson, Chris Venhaus was one of the first people to make a cat 5 speaker cable. I have included a link to his site. The instructions are fairly detailed. You might want to re-build the cables using C .......
52: Tube DIY Asylum, Good Info.... Thanks (0.00)
Posted by MikeT on 2005-06-10, 12:04:56 (192.160.6.253)
I didn't know about the JJ's. I've been looking for a 2.5V 300B but did not want to spring for the TJ's. I'll have to check out the price of the JJ's. .......
53: Tube DIY Asylum, Re: Sovtek 2A3's....have a 30W dissipation rating??? (0.00)
Posted by MikeT on 2005-06-10, 09:01:38 (192.160.6.253)
They do - but I still think it's a bad way to go. You'd need to remember the amp will only work with Sovteks, and if Sovtek ever changed their design you'd be SOL. I'd feel much better with the standa .......
54: Tube DIY Asylum, Re: Does anyone else see this amp will going up in smoke? (0.00)
Posted by MikeT on 2005-06-10, 07:52:45 (192.160.6.253)
The 2A3 is rated for 300V. It looks like there's 314 V across the tube, per the schematic. Above spec, but not a disaster. I've been running Valve Art 2A3's at about 310V for over a year with no probl .......
55: Welborne Labs, ST-70 With Welborne Mod For Sale (0.00)
Posted by MikeT on 2005-06-09, 14:34:16 (192.160.6.253)
See my add in the classifieds under "tube amps." Thanks for letting me post this, Ron. .......
56: Tubes Asylum, Re: Just click on the non-USA/Canada link for access... (0.00)
Posted by MikeT on 2005-06-09, 13:12:45 (192.160.6.253)
I tried that; it denied me access. I'll try it from home tonight to see what happens. They got into a snit with New Sensor, and cut off an entire continent. .......
57: Tubes Asylum, Is Svetlana Run By Children Or Adults? (0.00)
Posted by MikeT on 2005-06-09, 08:54:21 (192.160.6.253)
No access to the Svetlana web site from the U.S. and Canada. Pisses me off every time. Rant off. .......
58: SET Asylum, I Stand Corrected: My First SEP Experience (0.00)
Posted by MikeT on 2005-05-20, 10:59:49 (192.160.6.253)
Can triode strapping and 300B's driven by 2A3's be far behind? .......
59: SET Asylum, My First SET Experience (0.00)
Posted by MikeT on 2005-05-20, 08:02:59 (192.160.6.253)
Until now, I've been building push-pull pentode and triode amps. Last week I ordered a couple of 125ESE's just for kicks. I built a simple SE amp, 12SN7 driver > Allied IT > EL34 in pentode mode, B+ a .......
60: Bottlehead Forum, Re: BPS (0.00)
Posted by MikeT on 2005-05-17, 12:11:23 (192.160.6.252)
The BPS is a great gun. Smooth action, good balance, and it takes a licking. I've used it for dove, quail, duck, and yes, geese. I've even gotten doubles when dove hunting, which amazes my autoloader .......
61: Bottlehead Forum, Re: As if the frogs weren't bad enough (0.00)
Posted by MikeT on 2005-05-13, 12:57:47 (192.160.6.252)
A 12 gauge magnum load with a full choke will work just fine. I prefer the Browning pump. I'm left handed, and it has a bottom eject. .......
62: Tube DIY Asylum, Re: Mechanical Vibration reduction (0.00)
Posted by MikeT on 2005-05-10, 11:17:04 (192.160.6.252)
I've used these sorbothane hemispheres with good results. I set the amp on a plate, and supported the plate with about six of the hemispheres. This did a good job damping vibration coming from the rac .......
63: Tube DIY Asylum, Re: No Gettin' Around the Ole Laws of Physics.... (0.00)
Posted by MikeT on 2005-05-08, 16:49:56 (63.249.44.17)
The charge density is not changing with time. The elements that make up the inductor are not spontaneously transmuting into other elements, therefore the charge and charge density is fixed. http://sci .......
64: Tube DIY Asylum, No Gettin' Around the Ole Laws of Physics.... (0.00)
Posted by MikeT on 2005-05-08, 15:35:17 (63.249.44.17)
Read 'em and weep. http://en.wikipedia.org/wiki/Kirchhoff's_circuit_laws http://en.wikipedia.org/wiki/Conservation_of_energy http://en.wikipedia.org/wiki/Inductance http://en.wikipedia.org/wiki/Curren .......
65: Tube DIY Asylum, Sovtek 2A3 Specs (0.00)
Posted by MikeT on 2005-05-06, 10:58:41 (192.160.6.252)
Can someone point me to the specs for the Sovtek 2A3? Is it essentially a 300B with 2.5 V filaments? TIA! .......
66: Tube DIY Asylum, Same Thing Happened to Me (0.00)
Posted by MikeT on 2005-05-02, 14:19:29 (192.160.6.252)
A couple years ago I was running a Sovtek 5AR4 in a linestage with a 50 uf first cap, and about a 20 ma load on the tube. After about a week, I'd hear an occasional "rustling leaf" and popping sound. .......
67: Bottlehead Forum, Re: Post #2000 (0.00)
Posted by MikeT on 2005-04-22, 08:48:51 (192.160.6.252)
You've been a great help. I've referred to your web site many times. Thanks. Mike T. .......
68: Tube DIY Asylum, Re: Russian Teflon capacitors (0.00)
Posted by MikeT on 2005-04-01, 09:31:07 (192.160.6.252)
How was the buying experience? .......
69: Tube DIY Asylum, Re: Current Drive and High Zo (0.00)
Posted by MikeT on 2005-03-26, 09:22:17 (63.249.44.17)
It looks like several of us are on the same track, inspired by the same paper. Right now I'm running 6BN11 diff amp drivers into a 2A3 diff amp output stage. I'm experimenting with feedback from the U .......
70: Tube DIY Asylum, Current Drive and High Zo (0.00)
Posted by MikeT on 2005-03-25, 05:20:56 (192.160.6.252)
You guys might want to check out this article. It's a different way of looking at the world. .......
71: Tube DIY Asylum, Re: Cree diode availability (0.00)
Posted by MikeT on 2005-03-02, 08:26:02 (192.160.6.252)
Digikey sells similar diodes made by Infineon, part number SDT04S60IN-ND. Bad news is the minimum qty is 10. .......
72: Tube DIY Asylum, Pentode Screen Current Data (0.00)
Posted by MikeT on 2005-03-02, 08:19:40 (192.160.6.252)
Many pentode data sheets I've seen do not include screen curves. The Mullard EL34 sheet does contain this data, but many others either don't, or I'm overlooking it. How do I calculate screen current f .......
73: Tube DIY Asylum, Close to Insanity - Hum From Interconnects (0.00)
Posted by MikeT on 2005-02-26, 07:50:47 (63.249.44.17)
I can hook up a $90 Sony do-it-all home theater receiver to my subwoofer, DVD player, speakers, TV, cable box, and Tivo player. I can put my ear up to the speakers and hear no hum at all with my dog's .......
74: Tube DIY Asylum, Re: IXYS 10M45 CCS experience (0.00)
Posted by MikeT on 2005-02-16, 13:51:16 (192.160.6.252)
Tre, I don't know if you're aware of this, but the heat sink is electrically hot. It's at the same voltage as the input if it's not isolated electrically from the package. .......
75: Tube DIY Asylum, Check Out This Paper By Nelson Pass (0.00)
Posted by MikeT on 2005-02-10, 11:30:11 (192.160.6.252)
See this link: http://www.passdiy.com/articles.htm and see "Current Source Amplifiers and Sensitive / Full-Range Drivers" .......
76: Tube DIY Asylum, Which Hammond Tranny Did You Use? (nt) (0.00)
Posted by MikeT on 2005-02-07, 05:49:49 (192.160.6.252)
.......
77: Bottlehead Forum, Re: Loudspeaker Update Please (0.00)
Posted by MikeT on 2005-02-05, 16:12:25 (63.249.44.17)
Thanks for the info Paul. I look forward to seeing the Fostex design. .......
78: Bottlehead Forum, Loudspeaker Update Please (0.00)
Posted by MikeT on 2005-02-04, 10:52:26 (192.160.6.252)
I've been away from the board for a while. Can someone give me an update on Bottlehead speakers and plans, or point me to a post containing the info? Thanks in advance. .......
79: Tube DIY Asylum, The Local Pub Was Out of ESB...... (0.00)
Posted by MikeT on 2004-12-22, 17:36:15 (63.249.44.17)
... here in McKinney, Texas, so we fell back to Boddington's. Happy Holidays to you all. .......
80: K&K Audio / Lundahl Transformers, Re: IT Work At A Dead Stop Because of Hum (0.00)
Posted by MikeT on 2004-11-16, 10:09:10 (192.160.6.253)
I'm trying to build an all-transformer coupled system. I'm calling both the transformers (line stage to driver, and driver to power tube) interstage transformers. I'm going input phase splitting with .......
81: K&K Audio / Lundahl Transformers, IT Work At A Dead Stop Because of Hum (0.00)
Posted by MikeT on 2004-11-16, 08:29:32 (192.160.6.253)
I have been working my way up to investing in good IT's. As an experiment, I have tried both Edcor and Allied transformers to couple my balanced line stage to my balanced amp. Hum has been a majot fac .......
82: Tube DIY Asylum, Welcome Back (nt) (0.00)
Posted by MikeT on 2004-10-01, 14:46:04 (192.160.6.253)
.......
83: Tube DIY Asylum, 12SN7's Have Worked Fine for Two Years (0.00)
Posted by MikeT on 2004-09-30, 11:37:39 (192.160.6.253)
Douglas, FWIW, I've been running a pair of GE 12SN7's at 10 ma and 250V plate for two years now with no problems. I use them about 2-3 hours a day with regulated DC filaments. .......
84: Tube DIY Asylum, Re: could someone specify what is needed to drive a 2a3? (0.00)
Posted by MikeT on 2004-09-30, 04:14:02 (63.249.44.17)
It's about 2K. .......
85: Tube DIY Asylum, Re: could someone specify what is needed to drive a 2a3? (0.00)
Posted by MikeT on 2004-09-29, 14:51:27 (192.160.6.253)
I'm driving a 2A3 with a 5687. B+ is 300V. Plate voltage is 180V. Grid bias is 7V. Current is about 25 ma. I'm using a .1 uf Panasonic film/foil coupling cap. It sounds good to me, but I designed it m .......
86: Tube DIY Asylum, Thanks For the Info (nt) (0.00)
Posted by MikeT on 2004-09-28, 04:32:06 (63.249.44.17)
.......
87: Tube DIY Asylum, Thanks! (0.00)
Posted by MikeT on 2004-09-28, 04:30:31 (63.249.44.17)
Good stuff. Thanks Kyle. .......
88: Tube DIY Asylum, Can You Provide Some Links? (0.00)
Posted by MikeT on 2004-09-24, 16:01:12 (63.249.44.17)
I've done a number of Google searches and have not found the info for EI transformers on line. Can you tell me some of the URL's? .......
89: Tube DIY Asylum, You Don't Get It (0.00)
Posted by MikeT on 2004-09-23, 04:35:52 (63.249.44.17)
When someone makes a post, take it at face value, unless you can give them some constructive guidance. Everyone is a newbie at some point. Newbies want to learn from people with more experience. I obj .......
90: K&K Audio / Lundahl Transformers, Check Out Nutshellhifi.com (0.00)
Posted by MikeT on 2004-09-22, 17:27:19 (63.249.44.17)
Lynn Olson has a couple of state of the art cutting edge power amps on his web site. They are all transformer coupled designs. Look at the Amity and Karna. The designs use Lundahl transformers through .......
91: Tube DIY Asylum, Transformer Design and Construction References? (0.00)
Posted by MikeT on 2004-09-22, 14:49:36 (192.160.6.253)
Can anyone point me to audio transformer design and construction reference books or documentation? Thanks in advance. Mike .......
92: Tube DIY Asylum, Thanks For The Info Shifty (0.00)
Posted by MikeT on 2004-09-22, 06:11:37 (63.249.44.17)
You did an experiment. You posted the results. The info might benefit someone. Keep up the good work. .......
93: K&K Audio / Lundahl Transformers, Re: Karna arrives! (0.00)
Posted by MikeT on 2004-09-15, 04:39:53 (209.223.60.231)
Hello Lynn, the amp looks great. I've always wondered why you don't shunt reg the output stage. Can you comment on that? I'm also pretty close to buying a couple of 6W6's and giving them a spin...... .......
94: K&K Audio / Lundahl Transformers, How Do You Like Your Amp's Sound? (0.00)
Posted by MikeT on 2004-09-14, 15:00:47 (192.160.6.253)
How would you compare it to capacitor coupled designs, and designs that use diff amp phase splitters? .......
95: K&K Audio / Lundahl Transformers, Transformer Impedance Rating (0.00)
Posted by MikeT on 2004-09-14, 09:28:50 (192.160.6.253)
No way I'll post this on the Tube DIY board! Does anyone know the frequency at which an audio transformer's impedance is measured? Is it 1 KHz, 20 Hz, the lowest speced freq of operation, or something .......
96: Tube DIY Asylum, You Bully (0.00)
Posted by MikeT on 2004-09-08, 14:51:19 (209.223.60.231)
I have travelled all over the world as part of my very important job. I've also seen sea beams dance off the shoulder of Orion. How arrogant of you to make a statement like that. Your mother was a ham .......
97: Tube DIY Asylum, E-Linear Amp: Votes for Favorite Tubes (0.00)
Posted by MikeT on 2004-08-27, 11:50:55 (192.160.6.253)
I've decided to build an E-linear amp. What are your favorite power pentodes and triode or pentode driver tubes? .......
98: MagneQuest/Peerless Forum, Please Mail Me With Contact Info (nt) (0.00)
Posted by MikeT on 2004-08-26, 08:33:34 (192.160.6.253)
.......
99: MagneQuest/Peerless Forum, Re: yep... tell me more.... (0.00)
Posted by MikeT on 2004-08-25, 11:34:12 (192.160.6.253)
It's an application like in a Lynn Olson type power amp. B+ 300V. Balanced input. 5687 driver in a diff amp with CCS tail, 20 ma or so per side, 180V plate, 7V grid. I want to drive 2A3's right now, a .......
100: MagneQuest/Peerless Forum, Push-Pull IT? (0.00)
Posted by MikeT on 2004-08-24, 13:40:04 (192.160.6.253)
Mike, do you make a push-pull interstage transformer? .......
101: Tube DIY Asylum, Re: am i shielding properly? (0.00)
Posted by MikeT on 2004-08-06, 08:18:52 (192.160.6.253)
Are you using AC or DC heaters? .......
102: Tube DIY Asylum, Thanks to Matts, Jim, and Others (0.00)
Posted by MikeT on 2004-07-12, 12:55:59 (192.160.6.253)
Uncle Ned posted that most output stages of guitar amps operate in Class A1 or Class AB1. Given that info, I can figure out a starting point for all sorts of tubes, like EL84, EL34, 6V6, KT88, etc. So .......
103: Tube DIY Asylum, Re: Clash of Cultures; best to just get over it. (0.00)
Posted by MikeT on 2004-07-09, 12:55:38 (192.160.6.253)
Dammit, I'm not asking anyone do my homework for me. I do my own homework. I'm just asking for some recommendations based on experience. I'll buy an amp, whip out a voltmeter, and measure my own OP's. .......
104: Tube DIY Asylum, Re: Guitar amp "magic" (0.00)
Posted by MikeT on 2004-07-09, 11:11:44 (192.160.6.253)
Thanks for the inputs Steven. I fully agree that trial and error and voicing amps by ear is the best approach, just like designing hi-fi amps. It's why I like DIY to begin with. I'm just looking for s .......
105: Tube DIY Asylum, I Gotta Get This Off My Chest (0.00)
Posted by MikeT on 2004-07-09, 10:03:34 (192.160.6.253)
Matt, I don't think the guys on those forums know what they are talking about, so they hide their ignorance in non-descript terms like "saturation" and "distortion." If I ask people on this forum for .......
106: Tube DIY Asylum, Re: what are you trying to do? (0.00)
Posted by MikeT on 2004-07-09, 09:54:56 (192.160.6.253)
I'm trying to find typical operating points for guitar amp stages. If you can point me to references I'd appreciate it. .......
107: Tube DIY Asylum, Frustrated - Slightly Off Topic - Guitar Amp Questions (0.00)
Posted by MikeT on 2004-07-09, 09:16:53 (192.160.6.253)
I've tried posting these questions on guitar amp forums, but I get flippant wise-guy responses so I've given up on those venues. ("We LIKE distortion, unlike you hi-fi guys", is the typical non-answer .......
108: Tube DIY Asylum, More Home Depot resources... (0.00)
Posted by MikeT on 2004-07-07, 08:04:27 (192.160.6.253)
Check out the bimetal hole saws. They are available in all sorts of sizes. They also include an arbor with a drill bit in the center for a great deal of precision with the hole location. If you use a .......
109: Tube DIY Asylum, Re: damper diodes + cap input filter? (0.00)
Posted by MikeT on 2004-06-12, 14:43:52 (66.82.9.40)
I've been running a 6BY5G with a cap input, for over two years, with no problems. I'm using a 4.7 uf cap as the first cap. I found data on Duncan's Munro's web site that states not to exceed 8 uf for .......
110: Propeller Head Plaza, What About a 3 meter Croatian? (nt) (0.00)
Posted by MikeT on 2004-06-11, 13:55:39 (192.160.6.253)
.......
111: Tube DIY Asylum, Good Program, Written By Aliens (0.00)
Posted by MikeT on 2004-06-08, 05:49:52 (66.82.9.12)
SW Cad is a good program, but it was written by people from another world. They violated the simplest and most fundamental rule of a Windows application. Clicking on an object does not select it. Unbe .......
112: Tube DIY Asylum, Try IXYS 10M45S (0.00)
Posted by MikeT on 2004-05-27, 07:30:46 (66.82.9.36)
I use the IXYS 10M45S high-voltage CCS, available from Digi-Key. It's cheap, easy, and works good for me. It's basically a depletion-mode FET. One device, a heat sink, and one resistor and you have a .......
113: MagneQuest/Peerless Forum, Thanks For The Info (nt) (0.00)
Posted by MikeT on 2004-05-24, 07:55:48 (192.160.6.253)
.......
114: MagneQuest/Peerless Forum, Sorry About the Controversy...... (0.00)
Posted by MikeT on 2004-05-23, 12:52:32 (66.82.9.33)
but the best small-volume cheesesteak is at my mom's house in Dunmore. The best place to drink beer from 3 PM until 2 AM, after your very last final, is Zeno's. There are times when I miss Pennsylvani .......
115: MagneQuest/Peerless Forum, You Nailed It, I Need a Bit More Info... (0.00)
Posted by MikeT on 2004-05-23, 09:14:55 (66.82.9.55)
First, thanks for the response. I don't seek a guarantee, there's no way to expect such a thing in the real world of EM fields. I was just looking for a first-order feel concerning applications. The r .......
116: MagneQuest/Peerless Forum, Mikey: Still Need Guidance on PPS (0.00)
Posted by MikeT on 2004-05-23, 06:28:38 (66.82.9.22)
Can it be used as an input phase splitter, either to a PA or line amp? In the past I've had some big problems with hum pickup when using unshielded trannies. .......
117: MagneQuest/Peerless Forum, What Type of Cap for Parafeed? (0.00)
Posted by MikeT on 2004-05-23, 06:25:40 (66.82.9.22)
Oiler? Solen? Other? .......
118: MagneQuest/Peerless Forum, EXO-173 Questions (0.00)
Posted by MikeT on 2004-05-19, 07:35:24 (192.160.6.252)
Can I use an EXO-173 at the input of a line stage? This would allow me to do phase splitting at the head end of the chain. Does it have/will it need mu-metal shielding to reduce hum in this applicatio .......
119: MagneQuest/Peerless Forum, How About Another Variation? (0.00)
Posted by MikeT on 2004-05-19, 05:01:41 (66.82.9.59)
Use EXO-173 as input phase splitter. First stage in diff amp configuration with CCS tail load. Gives really good PSRR and knocks hum down as soon as possible. .......
120: Welborne Labs, Voltage Reg Current Rating? (0.00)
Posted by MikeT on 2004-05-19, 04:50:41 (66.82.9.59)
What is the current rating of the HV regulator board? I need to regulate a load of about 350 ma. The reg will have to drop about 15V. .......
121: Tube DIY Asylum, I Am Both Polish and American....... (0.00)
Posted by MikeT on 2004-05-14, 17:18:54 (66.82.9.55)
and I still don't know what Par did wrong. In some circles, my name is spelled Nicodemus Tomaszewski. Looks good to me Par, keep posting. .......
122: Tube DIY Asylum, What is Englsih? (nt) (0.00)
Posted by MikeT on 2004-05-14, 17:16:07 (66.82.9.55)
.......
123: Tube DIY Asylum, Guitar Amp Equivalent of This Forum? (0.00)
Posted by MikeT on 2004-05-10, 09:47:13 (192.160.6.252)
Hey Joel, do you know of an equivalent forum to this one, devoted to DIY guitar amps? TIA .......
124: Tube DIY Asylum, 14AF7 Looks Like 12SN7 - What's The Difference? (0.00)
Posted by MikeT on 2004-05-04, 13:39:29 (192.160.6.252)
Eli, the 14AF7 info looks like it has specs pretty close to the 12SN7. What's the difference? .......
125: Tube DIY Asylum, Re: Does It Get Any Better Than 12SN7? (0.00)
Posted by MikeT on 2004-05-04, 13:35:05 (192.160.6.252)
I was thinking pentode driver with 2A3 final. .......
126: Tube DIY Asylum, Does It Get Any Better Than 12SN7? (0.00)
Posted by MikeT on 2004-05-04, 08:09:20 (192.160.6.252)
OK, I've been using the same 12SN7 diff amp line stage now for a couple of years. B+ 350V, 250V/9ma/8V, CCS tail load, DC filaments. My soldering iron is longing for attention. Does it get any better .......
127: Tube DIY Asylum, Your Nom de Guerre Always Makes Me Smile (nt) (0.00)
Posted by MikeT on 2004-04-28, 09:26:12 (192.160.6.252)
nt .......
128: Tube DIY Asylum, Thanks To Gary Pimm (0.00)
Posted by MikeT on 2004-04-27, 12:45:18 (192.160.6.252)
Gary, thanks for all your contributions. I've referred, once again, to the CCS presentation on your web site. It's gold! Your CCS performance measurements are also very valuable. Keep up the great wo .......
129: Tube DIY Asylum, Re: Impedance of voltage controlled CCS (0.00)
Posted by MikeT on 2004-03-10, 08:07:28 (128.251.168.93)
Huh. I thought it was nothing more than a depletion mode FET with a fancy name. What other circuitry can they fit on a TO-220 die? .......
130: Tube DIY Asylum, Re: Current setting resistor for IXYS CCS (0.00)
Posted by MikeT on 2004-03-09, 12:03:36 (128.251.168.93)
I've used pots for less current, (around 10 ma) with no ill results. The pot will need to dissipate about .14 watts. I'm not sure how it will hold up over time with 60 ma pumping through it. My gut sa .......
131: Tube DIY Asylum, How About Ixys Current Reg? (0.00)
Posted by MikeT on 2004-03-09, 07:37:14 (128.251.168.93)
I've been using the Ixys IXCP10M45S current regulator, available from Digi-Key for $1.70. I don't know why Ixys calls this device a current regulator - I think it's just a depletion mode FET. It comes .......
132: Tube DIY Asylum, ROTFL!!!!!!!! I Need Hernia Surgery (nt) (0.00)
Posted by MikeT on 2004-03-07, 06:53:26 (66.82.9.19)
.......
133: Tube DIY Asylum, Re: DHT filaments (0.00)
Posted by MikeT on 2004-02-10, 04:20:17 (66.82.9.16)
I'm using PP 2A3's with one filament transformer per pair, and fixed bias. The CT of the filament transformer is grounded. There is no hum, with my ear to my 97 db speakers. .......
134: Tube DIY Asylum, Transformer Configuration Sanity Check (0.00)
Posted by MikeT on 2004-02-09, 09:25:22 (128.251.168.94)
If I have a transformer that's described as 1:1+1, and I wire the secondary in series with a CT, and I put a 2V signal into the primary, does this mean I'll get 2V from CT to +, and CT to - ? If I hav .......
135: Tube DIY Asylum, Re: The moderators know what they are doing. But do you????? (0.00)
Posted by MikeT on 2004-02-05, 08:10:42 (128.251.168.94)
No, I don't know what I'm doing. I'm a complete idiot. Signing off now, good bye Cheap Jack........ .......
136: Tube DIY Asylum, Moderators: It's Like Banning Matches...... (0.00)
Posted by MikeT on 2004-02-05, 05:31:08 (66.82.9.45)
because someone lights a fire. Deleting Douglas's post is not going to solve the problem. For a given action, there might be a reaction. I've never before seen Douglas write a post like the one you gu .......
137: Tube DIY Asylum, Thanks To All For the Great Discussion (0.00)
Posted by MikeT on 2004-02-04, 07:48:27 (128.251.168.94)
Dave, Allen, Gary, and Lynn (in absentia), (and a phone call to Kevin Carter to discuss CCS and chokes): Thanks for all the info and insights. I learned a lot, and I owe you guys a beer or two. Maybe .......
138: Tube DIY Asylum, Re: I'm just trying to figure out how big the choke should be. ... (0.00)
Posted by MikeT on 2004-02-03, 12:43:32 (128.251.168.94)
I'm going to try a "PS choke" sized choke (like 10H or less), as opposed to a "plate load" choke size. My logic is that the primary of the OPT already provides the plate loading, and the purpose of th .......
139: Tube DIY Asylum, Good Idea, Thanks (nt) (0.00)
Posted by MikeT on 2004-02-03, 07:35:02 (128.251.168.94)
.......
140: Tube DIY Asylum, Allen: Please See Link To Lynn's Site (0.00)
Posted by MikeT on 2004-02-03, 04:14:48 (66.82.9.17)
Allen, please check out the figure on Lynn's site. It's entitled "Differential (Forced Balance)" The cathodes are tied together, and grounded through a resistor. The grids are fed in antiphase. The CT .......
141: Tube DIY Asylum, Check This Link On Lynn's Site (0.00)
Posted by MikeT on 2004-02-02, 18:15:53 (66.82.9.35)
Check out this link: http://www.nutshellhifi.com/library/Tube_Fest_Talk.html See "Forced Balance". It shows "choke or current source." .......
142: Tube DIY Asylum, Re: Choke Size for CT Load of PP OPT (0.00)
Posted by MikeT on 2004-02-02, 15:11:48 (128.251.168.94)
To use the choke instead of a CCS to force the OP tubes into differential mode. .......
143: Tube DIY Asylum, Choke Size for CT Load of PP OPT (0.00)
Posted by MikeT on 2004-02-02, 13:23:19 (128.251.168.94)
If I choke load the CT of a PP OPT, how big should the choke be? Please let me know ASAP, OK? .......
144: Tube DIY Asylum, A Good Plate Choke is Hard to Find..... (0.00)
Posted by MikeT on 2004-02-01, 21:27:42 (66.82.9.24)
if you are a cheapskate like me and you need an inductor to remain an inductor at 50-100 ma current. Any ideas where to look for sub-$50 (or el cheapo) devices? Hint: I'm such a cheapskate I've been t .......
145: Tube DIY Asylum, Roger That. Thanks (nt) (0.00)
Posted by MikeT on 2004-02-01, 21:23:30 (66.82.9.24)
.......
146: Tube DIY Asylum, I'm a Subject Matter Expert..... (0.00)
Posted by MikeT on 2004-02-01, 19:35:11 (66.82.9.39)
Grew up in Lackawanna county. Went to school in State College. Moved to north Texas in '78. I'll take winter in Pa. over summer in Tx. any time. As far as summer, 100/40% in Tx. is hotter than 90/90% .......
147: Tube DIY Asylum, Yes, But...... (0.00)
Posted by MikeT on 2004-02-01, 19:29:45 (66.82.9.39)
with all the recent talk of DC imbalance in push-pull stages, I thought - why not eliminate the DC altogether? A big resistor relative to Rp might look like a pretty good CCS for all intents and purpo .......
148: Tube DIY Asylum, How Do I Figure Out The Inductance? (0.00)
Posted by MikeT on 2004-02-01, 12:03:02 (66.82.9.40)
OK, so is there a way to calculate the inductance of a given winding, with knowledge of only the nominal impedance? Also, the phase angle is always 90 in textbooks, but there's always resistance, whi .......
149: Tube DIY Asylum, Impedance Spec for Transformers (0.00)
Posted by MikeT on 2004-02-01, 10:41:44 (66.82.9.25)
What frequency is used to spec an audio transformer's impedance? For example, if I have a transformer with a 10K primary, is this measured at 1 khz? 20 hz? 60 hz? .......
150: Tube DIY Asylum, Push-Pull Parafeed 2A3 Amp? (0.00)
Posted by MikeT on 2004-02-01, 10:08:32 (66.82.9.19)
Well, it's been cold and dreary in North Texas. I've had some spare time to think, and that usually gets me in trouble. I'm thinking of the following: B+ around 460 V Use 2A3 tubes, tied to B+ with a .......
151: Tube DIY Asylum, Opinions Needed About Harmon Kardon (0.00)
Posted by MikeT on 2004-01-28, 09:13:07 (128.251.168.94)
I can buy the following H-K equipment from a friend for less than $400. He has not fired them up since 1986.: The Harmon-Kardon tube-type equipment is as follows: Citation III-X FM Tuner Citation IV .......
152: Tube DIY Asylum, Re: Looking for Autoformer TVC........ (0.00)
Posted by MikeT on 2004-01-21, 11:28:45 (128.251.168.94)
Only if it's a genuine Bose wave radio! .......
153: Tube DIY Asylum, Re: Looking for Autoformer TVC........ (0.00)
Posted by MikeT on 2004-01-21, 11:28:45 (128.251.168.94)
Only if it's a genuine Bose wave radio! .......
154: Tube DIY Asylum, Re: Looking for Autoformer TVC........ (0.00)
Posted by MikeT on 2004-01-21, 11:27:09 (128.251.168.94)
What's a gnat's ass among friends? Good point, I was not thinking in those terms. What does your TVC do? .......
155: Tube DIY Asylum, Re: Looking for Autoformer TVC........ (0.00)
Posted by MikeT on 2004-01-21, 11:27:09 (128.251.168.94)
What's a gnat's ass among friends? Good point, I was not thinking in those terms. What does your TVC do? .......
156: Tube DIY Asylum, Looking for Autoformer TVC........ (0.00)
Posted by MikeT on 2004-01-21, 06:05:20 (66.82.9.22)
I need an autoformer TVC with more than 42 dB atten. This is the most I've found with standard in-wall speaker volume controls. Does anyone know of a source for a control with more range than 42 dB, s .......
157: High Efficiency Speaker Asylum, Thanks to All for the Good Discussion (nt) (0.00)
Posted by MikeT on 2004-01-20, 13:50:52 (128.251.168.94)
nt .......
158: High Efficiency Speaker Asylum, Thanks And To Respond to Your Questions...... (0.00)
Posted by MikeT on 2004-01-19, 05:04:32 (66.82.9.27)
First of all, thanks for the great post. This will give me some things to research. As far as budget, I'm looking for something in the Fostex price range or below. So, no more than $150 per driver. I .......
159: High Efficiency Speaker Asylum, Re: So Then What About Fostex in BR? (0.00)
Posted by MikeT on 2004-01-18, 14:20:31 (66.82.9.47)
Thanks Tim. My intuition says that designing horns is more like designing a musical instrument. The equations governing horn design are probably very complex, and are hard to model. This leads to expe .......
160: High Efficiency Speaker Asylum, Re: Let me clarify at least one question: (0.00)
Posted by MikeT on 2004-01-18, 11:26:45 (66.82.9.35)
Thanks Greg. I'm looking for some rules of thumb or theory. What makes a speaker designed for a certain cabinet type? Given that a speaker cabinet is basically a high pass filter, what is the result o .......
161: High Efficiency Speaker Asylum, Re: A Full Range of Confusion: Starting Point Needed (0.00)
Posted by MikeT on 2004-01-18, 10:42:35 (66.82.9.26)
I'm looking for recommendations based on the experience of others. This will weigh into my decision, which I will then make. That's the value of forums to me. If I wanted other people to decide for me .......
162: High Efficiency Speaker Asylum, Thanks Ken, please see my response to Tim Above (0.00)
Posted by MikeT on 2004-01-18, 09:38:12 (66.82.9.20)
Please check out my response above. If you can help answer those questions that would be great. Thanks for the input. I appreciate the comments about differing tastes, and I agree. I use my own ears .......
163: High Efficiency Speaker Asylum, So Then What About Fostex in BR? (0.00)
Posted by MikeT on 2004-01-18, 09:34:37 (66.82.9.20)
Yes, I agree with you and Ken (see his response below). Agrument and controversy are what makes these hobbies fun, and that much I accept. I was ranting somewhat and being sarcastic and I apologize fo .......
164: High Efficiency Speaker Asylum, A Full Range of Confusion: Starting Point Needed (0.00)
Posted by MikeT on 2004-01-18, 07:20:55 (66.82.9.16)
I am a total newbie to DIY speakers. Until I started looking into DIY speakers, I thought DIY tube design was controversial and confusing. DIY speakers set a new standard. I'm trying to pick a high ef .......
165: Tube DIY Asylum, Re: ART DI/O - replace 12AX7 with 12AT7?? (0.00)
Posted by MikeT on 2004-01-14, 09:55:26 (128.251.168.93)
I can't answer all your questions. I do know that the tube is in the A/D circuit of the Art DI/O. If you are using the Art as a DAC the tube is not in the circuit. If you are using the thing as a DAC, .......
166: Tube DIY Asylum, They Proabably Have Them... (0.00)
Posted by MikeT on 2004-01-14, 08:51:00 (128.251.168.93)
Greenlee makes all sorts of punches, but man they can get expensive! You might want to check the Greenlee web site for the type you're looking for. I'd bet they have it, but it will cost you! ::: TOPI .......
167: Tube DIY Asylum, Re: 2A3 Diff Amp Photo (0.00)
Posted by MikeT on 2004-01-12, 17:09:10 (128.251.168.93)
I'll work on it and let you know when I've got it. Mike .......
168: Tube DIY Asylum, Re: 2A3 Diff Amp Photo (0.00)
Posted by MikeT on 2004-01-12, 16:48:31 (128.251.168.93)
Thanks for the kind words. Push-pull has quite a following here on the forum, just check out the work done by Lynn Olson (nutshellhifi.com) and Allen Wright (vacuumstate.com). .......
169: Tube DIY Asylum, Re: 2A3 Diff Amp Photo (0.00)
Posted by MikeT on 2004-01-12, 04:53:06 (66.82.9.35)
Thanks. I'm using an Edcor 10K:10K for an IT. I don't have a schematic done yet; I'll send you one when I do if you'd like. .......
170: Tube DIY Asylum, 2A3 Diff Amp Photo (0.00)
Posted by MikeT on 2004-01-11, 13:52:47 (66.82.9.18)
Here's a photo of my 2A3 Diff Amp. Don't tell my wife I did not dust very well. .......
171: Asylum Feedback/Support, Aha! It's Under "Login" (0.00)
Posted by MikeT on 2004-01-08, 05:57:40 (66.82.9.28)
OK, I found the links under "Login". I have a suggestion - How about adding a "Manage Your Account" link or something similar on the main page, or on the "Feedback/Support" page? That way, geezers lik .......
172: Tube DIY Asylum, Re: line preamp suggestion (0.00)
Posted by MikeT on 2004-01-06, 08:47:29 (128.251.168.93)
Here's my suggestion re. a 12AU7 line stage. It will give you a good starting point, and you can make modifications from there: B+ voltage: 400V Plate voltage: 250V Tube current: 10 ma Plate resistor: .......
173: Asylum Feedback/Support, How Do I Change My Email Prefs? (nt) (0.00)
Posted by MikeT on 2004-01-01, 06:18:46 (66.82.9.18)
nt .......
174: Tube DIY Asylum, They Do Indeed Sound Wonderful...... (0.00)
Posted by MikeT on 2003-12-21, 05:55:09 (66.82.9.30)
I'm using a 2A3 diff amp output stage in a stereo amp, and it does indeed sound great. I too thank Douglas for his CCS guidance and for answering all my dumb questions. (I am too cheap to spring for D .......
175: Tube DIY Asylum, What The Other Guys Said...... (0.00)
Posted by MikeT on 2003-12-15, 09:39:30 (128.251.168.93)
Hello Paul. I may not be the best judge of the care and feeding of tubes, because in my DIY tube building I abuse them massively all the time. I think that running things ten mils over spec is no bigg .......
176: Tube DIY Asylum, Great Info - And Two More Questions (0.00)
Posted by MikeT on 2003-12-15, 09:32:34 (128.251.168.91)
Man, I owe you one Homer (Douglas). This is the difference between book learnin' and the real world. Two more questions, based on your experience: - How much headroom is enough? - Once the CCS conduct .......
177: Tube DIY Asylum, Why Is Headroom Needed? (0.00)
Posted by MikeT on 2003-12-14, 20:16:37 (66.82.9.32)
My brain is vapor locked today. I can see why the negative supply voltage should exceed the compliance of the CCS, but why would I need headroom, if I'm always feeding the amp with identical but out o .......
178: Tube DIY Asylum, Re: High bias in Dynaco ST 70 (0.00)
Posted by MikeT on 2003-12-14, 10:04:23 (66.82.9.19)
You should be OK, and here's why. With the stock 15.6 ohm resistor, Dynaco wanted to read 1.56 volts across the resistor. This corresponds to 1.56 volts/15.6 ohms, or 100 ma of bias current. Now you .......
179: Tube DIY Asylum, Youth and Innocence - Thanks For the Compliments! (0.00)
Posted by MikeT on 2003-12-14, 09:03:05 (66.82.9.46)
Ah, you make me feel young again. Innocent I am, I guess, when it comes to tubes. I've only been into tube audio for a couple of years. My rationale for the symmetric supply was, given a solid-state C .......
180: Tube DIY Asylum, Musings/Questions About Diff Amps (0.00)
Posted by MikeT on 2003-12-14, 07:19:49 (66.82.9.11)
There's been a lot of play lately about diff amps. I've always thought that noise is the biggest first-order impairment in a system, so I've been rolling ideas about diff amps around in my head for qu .......
181: K&K Audio / Lundahl Transformers, 1544a vs. 1676 for Input Phase Splitter (0.00)
Posted by MikeT on 2003-12-13, 10:40:56 (66.82.9.18)
Other than ratios, what are the advantages/disadvantages/tradeoffs in these two xfmrs when used for input phase splitting? I'll be driving it with a 2V CDP input. Also, does anyone have any idea how m .......
182: K&K Audio / Lundahl Transformers, Transformer Recommendations/Comments (0.00)
Posted by MikeT on 2003-12-11, 17:57:39 (66.82.9.24)
Last week I posted on the DIY Tube Asylum and got some good inputs regarding my ST70 OPT's - which I'm going to keep. Then, I went to Lynn's web site, where he discusses needing more current drive tha .......
183: Tube DIY Asylum, Solution!!!! (0.00)
Posted by MikeT on 2003-12-11, 04:11:42 (66.82.9.29)
Thanks Ray. Your post made me think of a solution. I will just use 43.96 radians per second, and stop worrying about this. .......
184: Tube DIY Asylum, Make Sure Your Amps Cut Off Above 7 Hz! (0.00)
Posted by MikeT on 2003-12-10, 14:54:43 (128.251.168.94)
I ran across this on a web page today and thought of you guys. I thought that a 220uf cap charged to 1000V was my biggest hazard, but man, was I wrong! "A 7Hz tone of sufficient amplitude can crack th .......
185: Tube DIY Asylum, LOL! Buy a Cup! :-) (nt) (0.00)
Posted by MikeT on 2003-12-07, 18:31:12 (66.82.9.13)
nt .......
186: Tube DIY Asylum, Ever Looked at 6BY5? (0.00)
Posted by MikeT on 2003-12-06, 05:53:07 (66.82.9.13)
I've always meant to ask you about your rectifier choice for the Raven. As much as I love the 6CJ3 for power amps, they are half wave rectifiers and use a pain in the butt base. For lower current apps .......
187: Tube DIY Asylum, Torque Is Life (0.00)
Posted by MikeT on 2003-12-06, 05:35:07 (66.82.9.13)
Low end grunt is right. The only things in life that matter are torque curves and how many joules your power supply can store. You need all that heavy metal spinning at high speed -lots of inertia to .......
188: Tube DIY Asylum, Is It A Stroker? (0.00)
Posted by MikeT on 2003-12-05, 18:05:09 (66.82.9.40)
Bore and stroke that bad boy to 383....... .......
189: Tube DIY Asylum, And The Winner Is........ (0.00)
Posted by MikeT on 2003-12-04, 07:37:46 (128.251.168.93)
Great discussion guys, thanks. I plan to stick with the ST70 OPT's for now, upgrade the IT's to Lundahl 1660S, and perhaps use 1544a's as phase splitters on the input to the linestage. I'll then run .......
190: Tube DIY Asylum, Re: OPT Observations/Suggestions For Balanced Amp (0.00)
Posted by MikeT on 2003-12-04, 07:25:47 (128.251.168.93)
I'm using the 10K:10K. The balance overall must be pretty good because I'm getting no hum or noise, which in the past has been a signature of the Edcor when I've used it. I plan to switch to a Lundahl .......
191: Tube DIY Asylum, Re: IT balance is more difficult, and harder to find (0.00)
Posted by MikeT on 2003-12-04, 07:22:00 (128.251.168.93)
I'm going to switch to 1660S IT's when I can afford to. Regarding the latest amp, what a monsta! An integrated amp, with power tubes driving power tubes, and two different B+ supplies. You are a wild .......
192: Tube DIY Asylum, OPT Observations/Suggestions For Balanced Amp (0.00)
Posted by MikeT on 2003-12-03, 08:13:55 (128.251.168.93)
I've built a balanced amp based on the ideas posted here by Lynn Olson, Allen Wright, and others. I'm using 2A3's driven by 5687's, with a 300V B+ and fixed bias for both stages. I'm also using an Edc .......
193: High Efficiency Speaker Asylum, Too Much Protein In The Bloodstream (0.00)
Posted by MikeT on 2003-11-28, 10:10:01 (66.82.9.42)
Roland, I know of what you write. The other night I drank about four beers and listened to "The Wind" by Warren Zevon. I then probably totally embarassed myself by posting a sappy story about how much .......
194: Tubes Asylum, Not That Simple (0.00)
Posted by MikeT on 2003-11-28, 08:33:53 (66.82.9.42)
Hello David. I take exception to some of what you've written. My concern is that in substituting tubes you can exceed the wattage rating of resistors. Assume someone is starting with a grounded cathod .......
195: Tube DIY Asylum, Re: Yes, a very emotional album and truly excellent. (0.00)
Posted by MikeT on 2003-11-26, 09:27:12 (128.251.168.93)
I feel the same way about him. I always enjoyed his dry, sardonic sense of humor, as reflected in his music. I too go back to the Excitable Boys days, and the blue album, which was very good. The albu .......
196: Tube DIY Asylum, Warren Zevon Fans........ (0.00)
Posted by MikeT on 2003-11-24, 20:26:38 (66.82.9.35)
If you are a long-time Warren Zevon fan and have not yet heard "The Wind", my advice is to grab a fifth of bourbon and box of cleanex and wait until everyone's fast asleep. The man was in my living ro .......
197: High Efficiency Speaker Asylum, Negative Port Length In Boxplot? (0.00)
Posted by MikeT on 2003-11-24, 19:11:03 (66.82.9.27)
Anyone know why I'd get a negative port length in boxplot? I'm trying to design an enclosure using the Eminence Beta 12 LT. .......
198: Tube DIY Asylum, Re: power transformer (0.00)
Posted by MikeT on 2003-11-23, 19:00:11 (66.82.9.40)
I use a One Electron BFTB1. I got it at Antique Electronic Supply, and I'm very happy with it. A very stout and heavy PT; I'm running it with almost 300 ma of HV load and it never breaks a sweat. It .......
199: Tube DIY Asylum, Check Out Edcor (0.00)
Posted by MikeT on 2003-11-15, 17:06:01 (66.82.9.39)
They have many flavors of matching transformers. You can do a parafeed arrangement if you're concerned about DC in the primary. The URL is www.edcorusa.com .......
200: Tweakers' Asylum, Great Job - How Did You Bevel The Aluminum? (0.00)
Posted by MikeT on 2003-11-08, 13:59:06 (66.82.9.43)
You do great work. They are beautiful. How did you bevel the aluminum? .......
201: Tube DIY Asylum, Lynn Olson or Others: Correct 6CJ3 Socket? (0.00)
Posted by MikeT on 2003-11-06, 15:01:24 (128.251.168.93)
I've seen conflicting info about 6CJ3 sockets. One site says the tube uses a MagNoval socket, and an RCA datasheet I've seen says "nine-pin small button novar". Which one is right? Are these indeed th .......
202: Tube DIY Asylum, Two Options (0.00)
Posted by MikeT on 2003-10-30, 05:35:43 (66.82.9.19)
You can buy a CCS from KandKaudio.com for about $15. You can build your own version of Gary Pimm's BBMCCS by checking out this link: http://home.pacifier.com/~gpimm/Battery_biased_ccs.htm Both of thes .......
203: Tube DIY Asylum, Thanks Gents (nt) (0.00)
Posted by MikeT on 2003-10-25, 17:42:33 (66.82.9.35)
nt .......
204: Tube DIY Asylum, Re: To Gary P or Other CCS Gurus: CCS, Bias, and Me (0.00)
Posted by MikeT on 2003-10-23, 10:34:07 (128.251.168.92)
Hello Dave, thanks for the inputs. Here's my rationale: There are some packages like International Rectifier's TO-220 Fullpack that are electrically isolated. There is plastic all around the part that .......
205: Tube DIY Asylum, To Gary P or Other CCS Gurus: CCS, Bias, and Me (0.00)
Posted by MikeT on 2003-10-23, 08:33:04 (128.251.168.92)
I'd like to implement some CCS circuits, using TO-220 full or other isolated high power packages. I want to do this so I don't need heat sinks, or if it turns out I do need them then I don't want them .......
206: Tube DIY Asylum, Re: Mike, another question (0.00)
Posted by MikeT on 2003-10-22, 20:20:51 (66.82.9.23)
From reading your post again, it looks like you can use a fixed 12V regulator. If you want to build an adjustable one, here is the kit that I bought: http://electronickits.com/kit/complete/powe/ck403. .......
207: Tube DIY Asylum, Good Advice From Hifitom (0.00)
Posted by MikeT on 2003-10-22, 20:08:28 (66.82.9.23)
A fixed regulator at 12V would work just as well, and the one Hifitom recommends is just about the same as the LT1085, only fixed. You'll be running the heaters at 95% of the nominal 12.6V, which shou .......
208: Tube DIY Asylum, Re: Need Help Selecting a Good 12 volt heater regulator (0.00)
Posted by MikeT on 2003-10-22, 17:39:30 (66.82.9.41)
I use a Linear Technology LT1085. It's a three amp, low drop out adjustable regulator. When I first used it for two 12SN7 heaters, I found it was going into thermal overload. I added a 15W TO-220 heat .......
209: Hi-Rez Highway, Re: The Schematic, And Input Needed From DAC Experts (0.00)
Posted by MikeT on 2003-10-22, 17:16:32 (66.82.9.41)
I bought the service manual from Pioneer service parts, for about $30. I found the phone number on the Pioneer web site. .......
210: Hi-Rez Highway, The Schematic, And Input Needed From DAC Experts (0.00)
Posted by MikeT on 2003-10-20, 15:37:58 (66.82.9.11)
I'm looking at the schematic for the DV-563A-S. There are three DACs: A DSD-1791 is used for the front channels. This DAC outputs a balanced voltage signal, which is converted to unbalanced and filter .......
211: Tube DIY Asylum, Zener Biased FETs- Noisy? Bypass Caps Needed? (0.00)
Posted by MikeT on 2003-10-15, 13:51:16 (128.251.168.92)
Are zener-biased FET CCS's really noisy? Is a bypass cap needed across the zener? What size cap is needed? .......
212: Tube DIY Asylum, Re: My Guess at Allen Wright's New PP Application (0.00)
Posted by MikeT on 2003-10-15, 09:27:52 (128.251.168.92)
Hi Joel. My advice is - don't make yourself crazy. Most of the changes that occur in an unregulated amp's voltage settings are due to variations in AC line voltage. For example, here in the Dallas are .......
213: Tube DIY Asylum, My Guess at Allen Wright's New PP Application (0.00)
Posted by MikeT on 2003-10-15, 08:07:14 (128.251.168.92)
Since VSAC is over, and Allen showed his design, I guess the "magic box" is public domain. I have not seen a published schematic, but I'm in the process of overhauling an amp, so I want to take a stab .......
214: Tube DIY Asylum, Re: I have and I was pleased. (0.00)
Posted by MikeT on 2003-09-28, 08:21:52 (66.82.9.26)
Good call on HV trace spacing, it was a good memory jogger for me. One thing that gets messy when using PC boards and tubes is all the connectivity issues required between the tube sockets and the boa .......
215: Tube DIY Asylum, Just Say No While Mixing (nt) (0.00)
Posted by MikeT on 2003-09-28, 07:12:21 (66.82.9.28)
nt .......
216: Tube DIY Asylum, Thanks, This Helps a Great Deal...... (0.00)
Posted by MikeT on 2003-09-27, 06:29:25 (66.82.9.36)
....and as usual I am very impressed by and thankful for the contributions you make. Do you buy your PCB's from these folks? .......
217: Tube DIY Asylum, Thanks Kurt, You Made Me Smile! (nt) (0.00)
Posted by MikeT on 2003-09-27, 04:14:25 (66.82.9.31)
nt .......
218: Tube DIY Asylum, Schematic Drawing Program Recommendations (0.00)
Posted by MikeT on 2003-09-26, 18:20:46 (66.82.9.31)
I often want to share my schematics with you folks and solicit your inputs. I am vexed by the lack of schematic drawing packages. Some have suggested SwitcherCad, but I humbly submit - it sucks. It is .......
219: Tube DIY Asylum, Nice Amp - What Did You Use to Draw Schematic? (nt) (0.00)
Posted by MikeT on 2003-09-26, 11:58:26 (63.99.202.218)
(nt) .......
220: Tube DIY Asylum, Re: Stepped Attenuators (0.00)
Posted by MikeT on 2003-09-24, 09:30:20 (63.99.202.218)
Marchand Electronics sells a 24-step kit for about $75, IIRC. They have 12, 24, and 46-step flavors. Parts Connexion sells a 4-deck 24-position Electroswitch rotary switch for around $60. .......
221: Tech Square, Skin Effect At Audio Frequencies (0.00)
Posted by MikeT on 2003-09-21, 09:20:47 (66.82.9.47)
Is skin effect a factor at audio frequencies? I remember being taught this was not appreciable below UHF frequencies, and for all practical purposes did not have any impact below 1 Ghz. It also seems .......
222: Tube DIY Asylum, Re: Foreplay tube preamp (0.00)
Posted by MikeT on 2003-09-18, 11:34:16 (63.99.202.218)
I highly recommend the Foreplay. It's what got me started in this tube mania two years ago. If you'll go to the Bottlehead web site there are links to other sites that contain more information about t .......
223: Tube DIY Asylum, It's For The Simple Minded (0.00)
Posted by MikeT on 2003-09-17, 20:21:31 (66.82.9.32)
I had to create that convention so that simple minded engineers would not become confused. Physicists used to understand such things as second nature, until my colleague Albert Einstein confused them .......
224: Tube DIY Asylum, Curses....Foiled Again (0.00)
Posted by MikeT on 2003-09-17, 16:10:58 (66.82.9.16)
And I thought my motives were clever and difficult to discern. I single-handedly invented electricity at least 20 years before anyone else, with the sole motive of selling everything of or relating to .......
225: Tube DIY Asylum, Regarding UL........ (0.00)
Posted by MikeT on 2003-09-17, 13:31:47 (63.99.202.218)
I have found that 40% UL taps seems to be the norm, and works best in UL applications with pentodes such as the EL34. I prefer DHT triodes in push-pull, coupled with transformers or other inductive de .......
226: Tube DIY Asylum, One More Vote From the Pro Lynn Camp (0.00)
Posted by MikeT on 2003-09-16, 12:18:05 (63.99.202.218)
I feel I need to chime in. Lynn Olson and the rest of the people on this forum have been a great help to me as I pursue this hobby. Lynn does not offer products for sale, so I don't understand that pa .......
227: Tube DIY Asylum, More Thoughts....... (0.00)
Posted by MikeT on 2003-09-15, 07:56:46 (63.99.202.218)
Last year I experimented with the 6N1P. During the course of this I found some application info on the Svetlana web site. I've attached a link. My only other suggestion is to check the tube socket its .......
228: Tube DIY Asylum, Coupling Cap? (0.00)
Posted by MikeT on 2003-09-14, 18:39:57 (66.82.9.18)
Are you using a coupling cap between stages? If not, then you are hitting the grid of second triode with whatever voltage is on the plate of the first triode. This could be messing up the bias unless .......
229: Tube DIY Asylum, Grid Leak Resistor Needed? (0.00)
Posted by MikeT on 2003-09-14, 06:34:07 (66.82.9.40)
It sounds like the grid does not have a ground reference. Are you using grid leak resistors? If not, take a large resistor and connect it between each grid and ground. I usually use 1 meg. ::: TOPIC:: .......
230: Tube DIY Asylum, Re: Rectifiers for 6B4G PP stereo PSU (0.00)
Posted by MikeT on 2003-09-13, 01:06:39 (66.82.9.18)
I just built a stereo 2A3 PP amp. I used a One-Electron BTF1B power transformer and a pair of 6CJ3 damper tubes as rectifiers. It's a really stout combination; the PT does not even get warm, and it's .......
231: Tube DIY Asylum, My Brief Experience..... (0.00)
Posted by MikeT on 2003-09-08, 08:10:23 (63.99.202.218)
Hello Douglas - I hope you've been doing well. Just this weekend I got a new stereo PP 2A3 amp fired up. It's working pretty good. Into 90 db speakers, there is no hum on one channel, and a considerab .......
232: Tube DIY Asylum, Re: How About Solen Caps on AC Line? (0.00)
Posted by MikeT on 2003-09-04, 09:17:15 (63.99.202.218)
Tony, I think only caps that are X and Y rated should be used for AC mains applications. The risks are just too great if other types of caps are used, IMHO. .......
233: Tube DIY Asylum, Another Choice...... (0.00)
Posted by MikeT on 2003-09-04, 08:09:27 (63.99.202.218)
Try Goldpoint too....... .......
234: Tube DIY Asylum, Check Out DACT...... (0.00)
Posted by MikeT on 2003-09-04, 08:01:26 (63.99.202.218)
Here is a link to Lynn Olson's web site....... .......
235: Tube DIY Asylum, A Couple of Suggestions........ (0.00)
Posted by MikeT on 2003-09-04, 07:59:10 (63.99.202.218)
Have you calculated the wattage of the cathode resistors? I have used 1/8W resistors before without doing the calcs and have had them drift when they heat up. They were not always that hot to the touc .......
236: Tube DIY Asylum, Re: Parafed interstage (0.00)
Posted by MikeT on 2003-08-28, 12:38:31 (63.99.202.218)
See this link. An interstage application is treated the same as the output stage configurations shown on Steve's link. In parallel feed you are using either a choke or a CCS load for the tube, with a .......
237: Tweakers' Asylum, Danger!!!!!... (0.00)
Posted by MikeT on 2003-08-27, 13:20:59 (63.99.202.218)
It's because the caps are not specifically made for the application (high current AC power), and can fail, catch on fire, and burn your house down. If that happens, and no one is hurt, the insurance c .......
238: Tube DIY Asylum, Re: What is cascading caps? (0.00)
Posted by MikeT on 2003-08-27, 09:02:36 (63.99.202.218)
It probably means wiring two caps in series to get a higher net voltage rating. For example, if you connect two 100 uf 450V caps in series, you will end up with an aggregate cap that's 50 uf at 900V. .......
239: Tube DIY Asylum, Re: Simple Design (0.00)
Posted by MikeT on 2003-08-25, 14:13:47 (63.99.202.218)
I agree with Dogcab, JE Labs is a good site. Also, check out Pete Millet's web site; it has push-pull projects using DHT's and pentodes. He also has a "universal" amp design and will sell a PCB, IIRC. .......
240: Tube DIY Asylum, Re: Bull S*ht! (0.00)
Posted by MikeT on 2003-08-22, 14:22:49 (63.99.202.218)
You are right Quest. I feel there's a lot of that going around. .......
241: Tube DIY Asylum, New Speaker Design Will Be Needed (0.00)
Posted by MikeT on 2003-08-21, 09:25:30 (63.99.202.218)
You Bottlehead boys better get started on a new speaker design then. Assuming 10% efficiency, the Straight Eight will need to be expanded to the Straight 10,000. .......
242: Tube DIY Asylum, I Had the Same Thing Happen to Me (0.00)
Posted by MikeT on 2003-08-20, 11:16:26 (63.99.202.218)
It sounds like the LM is going into thermal shutdown, as others have written. A similar thing happened to me. I think the LM 350 has a drop-out voltage around 2.5V at 1.5 amps. So, any input voltage t .......
243: Tube DIY Asylum, If It's Angels Singing....... (0.00)
Posted by MikeT on 2003-08-19, 11:37:42 (63.99.202.218)
they've been smoking Lucky Strikes and taking lessons from Tom Waits! .......
244: Tube DIY Asylum, Re: Generic Tube Question (0.00)
Posted by MikeT on 2003-08-19, 09:03:31 (63.99.202.218)
Check out this link: http://www.tubecad.com/articles_2003/Grounded_Cathode_Amplifier/page10.html It gives a pretty good explanation of gain. .......
245: Tube DIY Asylum, Keith Jarrett Hum Filter Needed......... (0.00)
Posted by MikeT on 2003-08-19, 08:44:24 (63.99.202.218)
I love the man's piano, but those noises he makes have got to go. I think they call it humming, but I'm not sure. Maybe we need to design an adaptive 20th-order notch filter that's tuned to his resona .......
246: Tube DIY Asylum, I Didn't Know You Needed "Ultrapath".... (0.00)
Posted by MikeT on 2003-08-18, 08:55:49 (63.99.202.218)
with a push-pull design, since it's normally a noise cancellation technique for SE circuits. Thanks for the link, it looks pretty good, and I think I'm about to learn something! .......
247: Tube DIY Asylum, Why The Cap Between HV and Filament CT in Amity? (0.00)
Posted by MikeT on 2003-08-18, 08:02:46 (63.99.202.218)
Well, I've been pondering the cap between the HV and the DHT filament CT in the Amity and I can't figure out why it's there. My brain hurts. Please help. BTW: I'm about to take another foray into usin .......
248: Tube DIY Asylum, Russian Tube Designations and How To Find Data (0.00)
Posted by MikeT on 2003-08-14, 10:28:58 (63.99.202.218)
I'm looking for 6C45 data; I think this a Russian tube. Anyway, I can't find it on Duncan's page or Frank's directory. Does anyone know how to enter the tube's designator so I can find it? Also, this .......
249: Tube DIY Asylum, Re:"Are you serious" posted by Pete Millet dd aug 01, 2003 #205.245.252.13 (0.00)
Posted by MikeT on 2003-08-05, 16:28:43 (66.82.9.42)
My most recent experience is with a Sovtek 5AR4. I was running it with a 47 uf first cap, well within the "design spec" of 60 uf. Within six months the tube was arcing and sparking. I for one believe .......
250: Tube DIY Asylum, Re: Inline power filters?????? (0.00)
Posted by MikeT on 2003-08-03, 16:47:44 (66.82.9.38)
In general, these are "pi" filters that contain inductors that are in series with the AC lines, and capacitors that are connected between hot and ground and neutral and ground. The inductors block hig .......
251: Tube DIY Asylum, Pretty Good Analog Design Treatise..... (0.00)
Posted by MikeT on 2003-08-01, 14:02:55 (63.99.202.218)
I stumbled across this today. It's a big file though, over 1 Mb: http://www.analog.com/UploadedFiles/Associated_Docs/534294954127648933Section9.pdf .......
252: Tube DIY Asylum, Orange Drop or Panasonic ECQP (Digikey) (0.00)
Posted by MikeT on 2003-07-31, 18:34:59 (66.82.9.12)
I've tried both and liked them. It's a good interim step before trying higher-priced varieties. I've never found that capacitor sonics make a difference in a well-designed circuit, but that's just me. .......
253: Tube DIY Asylum, Re: To heck with silver, I am going to go Super Conductor... (0.00)
Posted by MikeT on 2003-07-30, 12:59:51 (63.99.202.218)
Just think - no noise and no resistance. You could use any type of wire you want and it would not make a difference! No need to watch out for phonons either. Now, if you could just accelerate to the s .......
254: Tube DIY Asylum, Re: 6n1p-300B schematics (0.00)
Posted by MikeT on 2003-07-30, 09:00:38 (63.99.202.218)
Here's a driver stage you might try....... http://www.svetlana.com/docs/TechBulletins/appnoteNO.27.html .......
255: Tube DIY Asylum, You're Welcome, Glad to Help (nt) (0.00)
Posted by MikeT on 2003-07-30, 08:56:53 (63.99.202.218)
nt .......
256: Tube DIY Asylum, Digikey Sells Their Discrete Diodes (0.00)
Posted by MikeT on 2003-07-30, 08:55:37 (63.99.202.218)
They also carry double-diode blocks but not the bridges. Maybe Ixys will sell you samples. .......
257: Tube DIY Asylum, Michael Percy Has Them (0.00)
Posted by MikeT on 2003-07-29, 18:41:28 (66.82.9.14)
http://www.percyaudio.com/ .......
258: Tube DIY Asylum, If You Can Get Me A Schematic I'll Try to Help (0.00)
Posted by MikeT on 2003-07-29, 08:10:33 (63.99.202.218)
Julien, if you can get me the schematic somehow I'll take a look. When you find one just post and we'll figure out how you can get it to me. You might also contact these guys, they might have one or k .......
259: Tube DIY Asylum, What Model Amp Is It? (0.00)
Posted by MikeT on 2003-07-28, 09:37:25 (63.99.202.218)
Hello Julien. I'm going to try to find a schematic and see if I can help you out. What mfg. and model amp is it? Mike .......
260: General Asylum, To The Bored: Ads By Google Pop-Up (0.00)
Posted by MikeT on 2003-07-23, 16:54:04 (66.82.9.18)
Gents, it seems that sometimes I get an "ads by Google" pop-up when I'm browsing posts. What is this diabolical invasion, and how do I get it to stop? Is anyone else having this problem? .......
261: Tube DIY Asylum, Did You Use CCS Loads on The Tails? (0.00)
Posted by MikeT on 2003-07-17, 18:12:43 (66.82.9.45)
I know you spent some time experiment with depletion mode FET CCS. Did you use them? Where did you bias the splitter and driver? .......
262: Tube DIY Asylum, Ping Sector-7G (0.00)
Posted by MikeT on 2003-07-17, 14:16:30 (63.99.202.218)
Hello Douglas. A couple of months ago you polled the group for some recommendations concerning a push-pull amp project. Did you ever build it? What topology and parts did you settle on? How does it so .......
263: Tube DIY Asylum, More Info On Topology and What Happened (0.00)
Posted by MikeT on 2003-07-17, 05:47:08 (66.82.9.45)
Here's more details: The linestage used a 12SN7 with regulated DC filaments and a C-L-C-L-C filter, with a 6BY5G rectifier. The power supply was in a separate box, with a five foot cable carrying the .......
264: Tube DIY Asylum, I Tried Edcors and They Picked Up Lots of Hum (0.00)
Posted by MikeT on 2003-07-16, 13:15:40 (63.99.202.218)
They are not shielded and I could never get them to run quiet in small-signal situations. I finally reverted bacck to cap coupling. .......
265: Tube DIY Asylum, Julien: Important: Groverg Is Right! (0.00)
Posted by MikeT on 2003-07-13, 15:30:47 (66.82.9.20)
Thanks Groverg, you are right. Sorry for the stupid mistake Julien. I need to take more time sometimes. .......
266: Tube DIY Asylum, Re: here is the article. (0.00)
Posted by MikeT on 2003-07-13, 15:26:41 (66.82.9.20)
Thanks, the "article" I remembered was a letter; in the response John Broskie referred to the article you reference. Here's the link to the letter: http://www.tubecad.com/april_may2001/page41.html My .......
267: Tube DIY Asylum, Wrong Value Of Ultrapath Cap? (0.00)
Posted by MikeT on 2003-07-13, 11:31:59 (66.82.9.20)
As I understand it, ultrapath is intended primarily to cancel hum in SE circuits, by summing the noise out of phase on an AC basis. That's why a cap is used for the ultrapath connection. You could hav .......
268: Tube DIY Asylum, Here's A Hint (0.00)
Posted by MikeT on 2003-07-13, 11:20:29 (66.82.9.20)
Check out this link: http://tdsl.duncanamps.com/show.php?des=EL34 It shows the basing for the EL34. Also note that the view of octal socket is viewed from the top of the socket. Pin 5 of the EL34 is t .......
269: Tube DIY Asylum, Re: Tube Newbie in need of Heeeeeelp! (0.00)
Posted by MikeT on 2003-07-12, 11:22:39 (66.82.9.45)
Some possibilities: 1. The tube is at end of life and needs to be replaced. 2. The bias of the tube failed for whatever reason and that forced the tube to glow bright red because it tried to draw way .......
270: Tube DIY Asylum, 2A3 Operating Point Recommendation (0.00)
Posted by MikeT on 2003-07-11, 08:22:52 (63.99.202.218)
I'm about to build a pp amp using Valve Art 2a3's. The most common operating point I see is 300V/45v/60 ma. Any other suggestions? I can go with fixed or self biased. I am going to use ST70 OPT's. Tha .......
271: Tube DIY Asylum, Re: What's a good tube to use for a Concertina (Split Load)? (0.00)
Posted by MikeT on 2003-07-02, 07:43:28 (63.99.202.218)
I went down this same road. I used a 12SN7. The concertina's PSRR is inherently low and the amp hummed like a banshee. I switched to a long tail pair with an active tail load and I've been happy ever .......
272: Tube DIY Asylum, Try This Article.... (0.00)
Posted by MikeT on 2003-06-20, 16:07:37 (12.238.173.154)
See the following link: http://www.tubecad.com/articles_2003/Grounded_Cathode_Amplifier/index.html .......
273: Tube DIY Asylum, But There Must Be a Frequency Component...... (0.00)
Posted by MikeT on 2003-06-16, 15:41:01 (12.238.173.154)
because unless a load is purely resistive there has to be a frequency-dependent component. .......
274: Tube DIY Asylum, How Are OPT's Speced? (0.00)
Posted by MikeT on 2003-06-16, 13:37:21 (63.99.202.218)
What frequency is used for an OPT's impedance spec? Is it 1 khz or something else? .......
275: Tube DIY Asylum, You Could Build A Nice Little Amp........ (0.00)
Posted by MikeT on 2003-06-14, 04:33:29 (12.238.173.154)
...... say a simple design like a 6N1P driving the EL84's push-pull into a Hammond 125ESE. Low B+ too. How about a single-ended version? .......
276: Tube DIY Asylum, You Are Such a Tease.........(nt) (0.00)
Posted by MikeT on 2003-06-09, 19:35:44 (12.238.173.154)
nt .......
277: Tube DIY Asylum, Check This Out (0.00)
Posted by MikeT on 2003-06-09, 13:54:54 (63.99.202.218)
http://www.tubecad.com/articles_2003/Grounded_Cathode_Amplifier/index.html .......
278: Tube DIY Asylum, Thanks for the Comments (0.00)
Posted by MikeT on 2003-06-08, 06:54:08 (12.238.173.154)
Thanks for the comments everyone. .......
279: Tube DIY Asylum, They Look Tough To Build...... (0.00)
Posted by MikeT on 2003-06-07, 09:48:02 (12.238.173.154)
so thanks for that input. I'm going to go back and look at them again. .......
280: Tube DIY Asylum, Tube Buddies: Need Speaker Advice (0.00)
Posted by MikeT on 2003-06-07, 06:47:16 (12.238.173.154)
I posted a message on the HE speaker asylum recently, asking for advice similar to this, and some butthead really flamed Wayne Parham, so I ain't doing that again! So, I'm posting this message here, w .......
281: Tube DIY Asylum, TubeCAD and Tube Manual Both Run On XP (0.00)
Posted by MikeT on 2003-06-05, 04:00:01 (12.238.173.154)
I am running both of these on the home version. I have no idea about the pro version. I've found that support for these programs is non-existent, I have never gotten a response from an email I've sent .......
282: Tube DIY Asylum, Try a Trimmer....... (0.00)
Posted by MikeT on 2003-06-01, 16:25:55 (12.238.173.154)
I use a trimmer pot to dial in the sound I want. Most times I leave them in. Sometimes I replace them with a fixed resistor. No graphs or formulae needed! Just make sure to use a multiturn pot, cranke .......
283: Tube DIY Asylum, A Fluke DVM Is All I Use....... (0.00)
Posted by MikeT on 2003-06-01, 16:22:02 (12.238.173.154)
for audio work! This is about fun, and with DIY I can use my own middle-age ringing tinitis too many Led Zepplin concert ears as the final arbiter. If I want 110 db S/N I can talk to guys at work who .......
284: Tube DIY Asylum, Broad Generalities (0.00)
Posted by MikeT on 2003-06-01, 16:16:44 (12.238.173.154)
In general, you want a driver tube to have a low plate resistance, good linearity, and relatively high current capability. This implies a medium or low mu tube. Examples are 6BL7, 6BX7 in octal and 56 .......
285: Tube DIY Asylum, A Starting Point (0.00)
Posted by MikeT on 2003-06-01, 12:04:24 (12.238.173.154)
Here's where I think you should start: Power Cable: Buy a shielded 14 ga Volex power cable from Allied Electronics. The shielding will help with local EMI. By local, I mean EMI generated by the other .......
286: Vinyl Asylum, Need Place To Sell Records - Dallas TX (0.00)
Posted by MikeT on 2003-06-01, 07:06:13 (12.238.173.154)
I am selling my collection of LP's. Can anyone recommend a record store in the Dallas area that will buy them? Thanks .......
287: Tube DIY Asylum, Re: Many times over (nt) (0.00)
Posted by MikeT on 2003-05-31, 11:18:43 (12.238.173.154)
Just wanted to make sure you were qualified to write what you are espousing. I'm an engineer too, and when it comes to tube audio I only use my ears. When I like what I hear that's what I go with. If .......
288: Tube DIY Asylum, I Have A Collins Radio Pickett Slide Rule....... (0.00)
Posted by MikeT on 2003-05-31, 11:14:29 (12.238.173.154)
it was specially made for microwave path calculations for Collins by Pickett. I will never part with it. .......
289: Tube DIY Asylum, Are You An Engineer? (nt) (0.00)
Posted by MikeT on 2003-05-31, 05:25:58 (12.238.173.154)
nt .......
290: Tube DIY Asylum, Re: In search of a power TX.... (0.00)
Posted by MikeT on 2003-05-25, 06:32:46 (12.238.173.154)
Try this one: http://www.toroid.com/standard_transformers/rectifier_transformers/rectifier_transformers_tube.htm Also, check out the One Electron power transformer at Antique Electronics. .......
291: Tube DIY Asylum, Don't Feel Too Bad, Same Thing Happened to Me... (0.00)
Posted by MikeT on 2003-05-24, 10:20:32 (12.238.173.154)
I have an ST70 and I was using a Sovtek 5AR4 with a 47uf first cap. The tube gave up the ghost last week. I have since switched to a 10uf first cap and a Chinese 5AR4. That could just be it - weak rec .......
292: Tube DIY Asylum, I'll Try 20 muf...... (0.00)
Posted by MikeT on 2003-05-23, 19:32:57 (12.238.173.154)
and I'm thinking of going solid state and using an HV regulator. Oh well, I sure wish Russian and Chinese manufacturers would publish specs for their products. .......
293: Tube DIY Asylum, How About CCS Plate Loads? (0.00)
Posted by MikeT on 2003-05-23, 08:33:33 (63.99.202.218)
Douglas, 56K should work fine, but the B+ is 430V, so you'd need to run at a lower plate voltage. I have run the NOS Sylvania 12SN7's down to 120V/4V/5ma before with no problems, but I must admit I li .......
294: Tube DIY Asylum, Here's the Tab (0.00)
Posted by MikeT on 2003-05-23, 06:12:56 (12.238.173.154)
Here's the tab for most of the stuff: Uncle Ned PT: $100 SDS Labs ST70 PS Kit: $50 1.5H Choke: $10 Sud Total: $160 Angela Black 17X14X3 Hammond Chassis: $57 Hammond 1650N, $61 ea, $122 a pair Sub Tota .......
295: Tube DIY Asylum, Check This Out (0.00)
Posted by MikeT on 2003-05-22, 21:27:03 (12.238.173.154)
http://www.weicowire.com/ Check out part number 2820. Solid 20 ga silver coated copper wire, teflon insulation, 600V rating. If you buy stranded you can get 1000V rating. I'm pretty sure all teflon in .......
296: Tube DIY Asylum, Latter Day ST70 (0.00)
Posted by MikeT on 2003-05-22, 21:16:45 (12.238.173.154)
-ST70 power tranny, power supply kit board, and power choke from Uncle Ned. -Shunt fed volume control using Alps pot or similar, or build a pair of 12 position shunt fed attenuators using Beyschlag re .......
297: Tube DIY Asylum, Re: How much capacitance (0.00)
Posted by MikeT on 2003-05-22, 14:00:07 (63.99.202.218)
I used 47uf for the first cap. The PS is: 47uf>1.5H>440uf I have read some older posts that said that the Sovtek 5AR4 really is not a 5AR4 and can only handle something like 8 uf. When I'm doing a pro .......
298: Tube DIY Asylum, LOL. Re-Injured My Hernia. Where Is My Truss? (nt) (0.00)
Posted by MikeT on 2003-05-21, 21:15:06 (12.238.173.154)
nt .......
299: High Efficiency Speaker Asylum, Thanks for All The Input (0.00)
Posted by MikeT on 2003-05-21, 19:20:42 (12.238.173.154)
Quite a bit of food for thought, along with a flame. (Man, take it easy guys, this is a hobby and is supposed to be enjoyable.) Anyway, the N803's are about to go along with a bunch of other stuff(I n .......
300: Tube DIY Asylum, Mystery Solved - Arcin' and Sparkin' (0.00)
Posted by MikeT on 2003-05-21, 17:16:10 (12.238.173.154)
So for the last few months I've had my amp blow fuses once in a while on power up. Didn't happen too often, I figured it was the sunspot cycle. Last week it really starts getting bad, and happening af .......
301: Tube DIY Asylum, Here's One (0.00)
Posted by MikeT on 2003-05-20, 19:36:06 (12.238.173.154)
Check out this link: http://www.aloha-audio.com/preamp.gif .......
302: Tube DIY Asylum, Yep, You May Be Right (0.00)
Posted by MikeT on 2003-05-20, 19:27:18 (12.238.173.154)
I think most of the tube data are the recommended operating conditions for the original vintage tubes, developed in order to minimize distortion for the stated power levels and class of operation. I d .......
303: Tube DIY Asylum, What I Do..... (0.00)
Posted by MikeT on 2003-05-20, 17:56:02 (12.238.173.154)
I go to the Duncan Amp web site and select the tube data sheet locator. For almost all the popular triode and pentode power tubes, there is a table that shows the recommended operating points for the .......
304: High Efficiency Speaker Asylum, HE Speaker Design Primer Needed (0.00)
Posted by MikeT on 2003-05-20, 17:14:52 (12.238.173.154)
Well, about two years ago I got interested in tube audio and started to learn about it on the DIY tube asylum. I'm now ready to take such a plunge into building my own HE speakers, and I need some gui .......
305: Tube DIY Asylum, I Tried It Owen......... (0.00)
Posted by MikeT on 2003-05-19, 22:32:58 (12.238.173.154)
First, let me explain my existing amp configuration, it's: 5687 long tail phase splitter with CCS tail load ,to EL34's push-pull UL, to ST70 OPT's. I'm using a 47uf>1.5H>440uf power supply, with a 5AR .......
306: Tube DIY Asylum, Re: ST-70 Parallel fed (0.00)
Posted by MikeT on 2003-05-19, 22:23:51 (12.238.173.154)
Thanks Alan. I'd come across that article a while back. It sounds like a good idea as a thought process, but there's no way to bias an EL34 to deliver 50-70 ma current from a 430V B+ and still have th .......
307: Tube DIY Asylum, Re: Also noted the Fullers ESB (0.00)
Posted by MikeT on 2003-05-19, 22:20:39 (12.238.173.154)
Not British, but I do like to visit, and I like the people, and the beer. Case in point. One time I was staying near Ipswich, in a 14th century (?) manor house converted into a hotel. So, I'm in the l .......
308: Tube DIY Asylum, Thanks Mike C and 7N7..... (0.00)
Posted by MikeT on 2003-05-17, 16:31:57 (12.238.173.154)
I tend to think in terms of EL34, SV83, EL84, and other pentodes I'm familiar with. Thanks for pointing out some other candidates. I must admit I have a bias toward mosfets though. (no pun intended) : .......
309: Tube DIY Asylum, You Are Right Joseph (0.00)
Posted by MikeT on 2003-05-17, 16:28:20 (12.238.173.154)
I talked with Supertex too. They told me that it's getting more and more difficult to find companies who will manufacture in TO-220 packages. The minimum order lot is 50 pieces. .......
310: Tube DIY Asylum, Thanks Paul, It Was 6EM7 But........ (0.00)
Posted by MikeT on 2003-05-17, 16:25:18 (12.238.173.154)
this one looks pretty good too! .......
311: Tube DIY Asylum, Good Source, Thanks, Ever Ordered From Them (nt) (0.00)
Posted by MikeT on 2003-05-17, 16:20:00 (12.238.173.154)
nt .......
312: Tube DIY Asylum, ST-70 Experiment - Anyone Done This? (0.00)
Posted by MikeT on 2003-05-17, 12:56:14 (12.238.173.154)
Today, after drinking a few Fuller's ESB's, I decided to try the following with my already hacked ST70: 1. Single ended parafeed connection 2. Two parallel EL34's 3. Drive with two parallel 5687 secti .......
313: Tube DIY Asylum, Where Can I Find Tube Data? (nt) (0.00)
Posted by MikeT on 2003-05-17, 08:40:11 (12.238.173.154)
nt .......
314: SET Asylum, Seriously, It's a Good Cable (0.00)
Posted by MikeT on 2003-05-15, 11:06:26 (63.99.202.218)
The Volex cable I referenced really is a good cable. It is well shielded, and I think that buys you the most when it comes powering audio equipment. I think you can couple a lot of local EMI into equi .......
315: Tube DIY Asylum, I often miss the point... (0.00)
Posted by MikeT on 2003-05-15, 04:59:30 (12.238.173.154)
except the one on my head! :-) Speed traps have gotten really bad where I live, since most local governments are deeply in the red, it's one of their only sources of income. .......
316: Tube DIY Asylum, Question About CCS Bias Source (0.00)
Posted by MikeT on 2003-05-15, 04:47:32 (12.238.173.154)
If a have several cascode Mosfet CCS's in a circuit, can I use a common bias source, like a 9V battery, to bias all of them? .......
317: Tube DIY Asylum, Good Advice, And Another Source (0.00)
Posted by MikeT on 2003-05-15, 04:42:28 (12.238.173.154)
Thanks Bas. Kevin Carter at KandK Audio will sell the piece parts to folks too, as I recall. We can take care of our own here at AA! .......
318: SET Asylum, Volex 17604 (0.00)
Posted by MikeT on 2003-05-14, 19:09:24 (12.238.173.154)
The best I ever had. $11 from Allied Electronics http://www.alliedelec.com/catalog/pf.asp?fn=409.pdf&Catalog=2002&PageNum=409 .......
319: Tube DIY Asylum, Ixys Depletion Mode Mosfets - Also Rare (0.00)
Posted by MikeT on 2003-05-14, 18:33:26 (12.238.173.154)
Here's the response from Ixys about their depletion mode mosfets: "Hello Mike we have stock in our facility. none of our disty's would have this in their inventory it's not a high runner in distributi .......
320: Tube DIY Asylum, They Seem To Have Low Impedance Though.... (0.00)
Posted by MikeT on 2003-05-14, 09:07:09 (63.99.202.218)
The Ixys spec sheet appears to have been written by Martians, so I can't really de-cipher some of it, but it looks like the impedance of these devices is very low. I don't understand how this can be t .......
321: Tube DIY Asylum, Bumbling and Stumbling at Mouser (0.00)
Posted by MikeT on 2003-05-14, 09:04:17 (63.99.202.218)
I ordered seven DN2540's off the Mouser web site yesterday; it showed they had them in stock, qty 7, price $1.53 each. Today, I get an email saying they shipped short. So I call Mouser and they told m .......
322: Tube DIY Asylum, Re: Dynaco ST70 quad cap replacement max? (0.00)
Posted by MikeT on 2003-05-14, 05:29:20 (12.238.173.154)
I'm running 47uf > 1.5H choke > 440 uf and I like the sound a lot. The bass response is really good too. .......
323: Tube DIY Asylum, Don't Fry Them, Confuse Them (0.00)
Posted by MikeT on 2003-05-14, 05:00:59 (12.238.173.154)
No need to smoke the front end of the radar receiver, as dramatic and fun as that would be. Just send a pulse back at a high enough power level so that the gun reads the legal speed limit no matter ho .......
324: Tube DIY Asylum, I've Seen That Valve Article Before...... (0.00)
Posted by MikeT on 2003-05-14, 04:56:35 (12.238.173.154)
Good looking amp. How did you develop the -v in the power supply? .......
325: Tube DIY Asylum, You Are Correct Sir! (0.00)
Posted by MikeT on 2003-05-13, 19:04:38 (12.238.173.154)
6EM7 is the one I was thinking of. One section looks kind of like a 6SL7, the other like a 2A3. May sound pretty good in SE parafeed. I'm not familiar with the 6EA7. I'll have to look it up. I don't s .......
326: Tube DIY Asylum, And If Chickens Had Lips.... (0.00)
Posted by MikeT on 2003-05-13, 18:15:34 (12.238.173.154)
then pigs could fly, and I wouldn't bump my ass a hoppin'. If all those things happened, n-channel depletion mode mosfets would still be more rare. The darn things are just hard to find. Must be a pro .......
327: Tube DIY Asylum, I Just Talked to Kevin at Supertex.......... (0.00)
Posted by MikeT on 2003-05-13, 16:38:26 (12.238.173.154)
and he says the DN2540 in TO-220 is still in current production. They are having trouble finding people who will package them in TO-220, so the reason the data sheets say not to use them in new design .......
328: Tube DIY Asylum, Then Their Web Site is Wrong..... (0.00)
Posted by MikeT on 2003-05-13, 16:24:21 (12.238.173.154)
and so are their data sheets, and as a result the whole world is confused. I'm going to send an email to Supertex and ask them if the part is still in production or not. .......
329: Tube DIY Asylum, Actually, I Got It From The Bottleheads! (0.00)
Posted by MikeT on 2003-05-11, 14:37:01 (12.238.173.154)
The Foreplay is what got me started with this DIY tube addiction, so I owe it all to Doc and the boys. I've also learned quite a bit from the forum and several of the web pages, especially Voltsecond' .......
330: Tube DIY Asylum, Try a Shunt Volume Control (0.00)
Posted by MikeT on 2003-05-11, 11:30:31 (12.238.173.154)
Take a good 50 K or 100 K resistor to feed the linestage, and tie the pots between the resistor and ground, like a voltage divider. This takes the pots out of the signal flow for the most part, and is .......
331: Tube DIY Asylum, Re: Should I add a better cap (0.00)
Posted by MikeT on 2003-05-11, 10:38:11 (12.238.173.154)
You could just add another Angela cap like the one you have to double the capacitance, if you have the space and the $$. Personally, I use Panasonic caps and I buy them from Digikey. I've used TSUP, T .......
332: Tube DIY Asylum, You Are Making The Cap Value Larger..... (0.00)
Posted by MikeT on 2003-05-11, 07:49:32 (12.238.173.154)
and as a result the power supply is storing more energy, that's why you hear more bass. The caps are there to store enough energy so that the PS voltage stays as constant as possible regardless of the .......
333: Tube DIY Asylum, Re: but if you roll that one back a bit... (0.00)
Posted by MikeT on 2003-05-10, 20:08:32 (12.238.173.154)
Kevin Carter's CCS is a single device, and Kevin says it sounds pretty good. I wonder if audio plate chokes, pentodes and gas VR tubes would have been invented if mosfets were around in the good old d .......
334: Tube DIY Asylum, Pentodes (0.00)
Posted by MikeT on 2003-05-10, 18:12:11 (12.238.173.154)
In general, you want to pick a pentode over a triode because they are superior as a CCS. With that said, my personal choice is to use FET CCS's because they require less B+ voltage and they are better .......
335: Tube DIY Asylum, And, For A Good Explanation of Output Structures.... (0.00)
Posted by MikeT on 2003-05-10, 06:52:14 (12.238.173.154)
See this link: http://members.aol.com/sbench/outstru.html Steve Bemch has done a really good job discussing the alternatives. I'm betting that if Mosfet CCS's had been available in the 1930's parafeed .......
336: Tube DIY Asylum, Parafeed - Absolutely (0.00)
Posted by MikeT on 2003-05-10, 05:31:48 (12.238.173.154)
Buy two CCS kits from Kevin at K and K audio for $20 each, including the heat sinks, and a couple of film and foil caps, and go to town. .......
337: Tube DIY Asylum, Re: Doesn't Anyone Know the Answer to This? (0.00)
Posted by MikeT on 2003-05-09, 05:09:14 (12.238.173.154)
Neutral is not tied to chassis though. It's only connected to the primary of the power transformer. .......
338: Tube DIY Asylum, Impedance (0.00)
Posted by MikeT on 2003-05-09, 04:39:28 (12.238.173.154)
The chassis is a lower impedance than you are, unless you are the tin man. .......
339: Tube DIY Asylum, Sector-7G: Amp Update (0.00)
Posted by MikeT on 2003-05-06, 17:43:28 (12.238.173.154)
Douglas, we exchanged posts a few weeks ago, as I was flopping around trying to understand long-tail pairs. (It's always simple, obvious, and logical AFTER you understand it, but that's life I guess.) .......
340: Tube DIY Asylum, Re: Time to conduction... (0.00)
Posted by MikeT on 2003-05-04, 15:55:20 (12.238.173.154)
Thanks, I never measured. I was just using my Mark 1 rev 0 ears as a reference. :-) OK, maybe my time base is off, especially after a few beers and some Pink Floyd. In any event, in my hacked ST70, th .......
341: Tube DIY Asylum, Yet More Ideas (0.00)
Posted by MikeT on 2003-05-04, 15:51:12 (12.238.173.154)
I have not done this, but there are people who are using transformer attenuators like the Radio Shack 40-987. There are also other brands. As I recall Edcor is also selling these loose. These devices .......
342: Tube DIY Asylum, Re: Seperate bias supply - ok if it hits heated tubes before B+? (0.00)
Posted by MikeT on 2003-05-04, 15:25:19 (12.238.173.154)
It will work fine. You definitely want the grid bias up and stable, and the filaments working, before you apply the HV. The scheme you are using is pretty standard. The 5AR4 will give you 15-30 sec de .......
343: Tube DIY Asylum, Re: Regulated DC filaments? (0.00)
Posted by MikeT on 2003-05-04, 13:18:09 (12.238.173.154)
If you use a bridge rectifier configuration you should be able to get about 9VDC or so from a 6.3VAC winding. If you use a low dropout regulator like an LT1085 you should be OK. As a first step, put t .......
344: Tube DIY Asylum, My Experience With Magnetic Fields (0.00)
Posted by MikeT on 2003-05-03, 04:43:43 (12.238.173.154)
In my linestage I have a power supply using a Hammond 300-0-300 power transformer, it's a C-L-C-L-C, 47uf - 10H - 200uf - 10H - 200 uf. The magnetic field generated by the PT is enormous. I found this .......
345: Tube DIY Asylum, Allied Electronics Has It (nt) (0.00)
Posted by MikeT on 2003-05-02, 04:42:04 (12.238.173.154)
no text .......
346: Tube DIY Asylum, Check out the TubeCad Top Level (0.00)
Posted by MikeT on 2003-04-30, 19:57:19 (12.238.173.154)
If you look at the very top level URL, www.tubecad.com, you'll see an archive to all the issues. I think Broskie started the site and news letters in 1998 or so. Most of the archives are on line on hi .......
347: Tube DIY Asylum, Check Out These Links for Audio (0.00)
Posted by MikeT on 2003-04-29, 06:44:59 (12.238.173.154)
One of the best explanations of triodes and how they work that I've seen is here: http://www.tubecad.com/articles_2003/Grounded_Cathode_Amplifier/index.html The article explains how grounded cathode a .......
348: Tube DIY Asylum, Re: What exactly is "Ham Radio" anyway? And how does it relate to High-End Tube DIY Audio? (0.00)
Posted by MikeT on 2003-04-29, 06:27:15 (12.238.173.154)
Ham radio is more properly called amateur radio. These are people who use radio to communicate with each other over long distances. They are licensed by the FCC and use certain parts of the radio spec .......
349: Tube DIY Asylum, I Second the ARRL Handbook (0.00)
Posted by MikeT on 2003-04-28, 16:54:27 (12.238.173.154)
I too suggest you buy a vintage ARRL handbook. Vintage, because you want discussions of tubes, not solid state. Any version from the late fifties will do. The ARRL Handbook was published every year, a .......
350: Tube DIY Asylum, Close Enough, Thanks (nt) (0.00)
Posted by MikeT on 2003-04-28, 05:58:03 (12.238.173.154)
nt .......
351: Tube DIY Asylum, Re: Need List of VR Tubes and Parameters (0.00)
Posted by MikeT on 2003-04-28, 05:53:10 (12.238.173.154)
I'm sure the 1970 edition I used to have is in the attic at my mom's house! .......
352: Tube DIY Asylum, Regulated Voltage and Current (nt) (0.00)
Posted by MikeT on 2003-04-27, 19:41:37 (12.238.173.154)
nt .......
353: Tube DIY Asylum, Check This Out (0.00)
Posted by MikeT on 2003-04-27, 18:17:38 (12.238.173.154)
I would add multiple outputs to the preamp. Emulate what's shown here: http://www.siteswithstyle.com/VoltSecond/Foreplay_outputs/foreplay_multiple_outs.html If you have any questions you can post to V .......
354: Tube DIY Asylum, Need List of VR Tubes and Parameters (0.00)
Posted by MikeT on 2003-04-27, 17:01:27 (12.238.173.154)
Can anyone point me to a table or list of VR tube types and parameters? .......
355: Tube DIY Asylum, You're Welcome (nt) (0.00)
Posted by MikeT on 2003-04-27, 12:59:03 (12.238.173.154)
nt .......
356: Tube DIY Asylum, Re: On more Question - What's a Modulator? (0.00)
Posted by MikeT on 2003-04-27, 11:40:38 (12.238.173.154)
A modulator is a functional block contained in a radio frequency transmitter. It takes the baseband signal and combines it with the carrier. The combination is what is transmitted. For example, in an .......
357: Tube DIY Asylum, Try Electraprint (0.00)
Posted by MikeT on 2003-04-27, 09:25:15 (12.238.173.154)
The URL is www.electraprint.com. There is an autoformer offered but I don't remember it's specs. The owner, Jack Elliano, might also build one custom to your specs. I know he does this for power trans .......
358: Tube DIY Asylum, It's Too Hard To Change Tracks When Wearing a Welder's Hat (nt) (0.00)
Posted by MikeT on 2003-04-26, 17:57:24 (12.238.173.154)
nt .......
359: Tube DIY Asylum, I Can Trump That - And Current Production Too! (0.00)
Posted by MikeT on 2003-04-26, 04:44:07 (12.238.173.154)
Check it out: http://www.tube.be/3cx3000f1.html "The 3CX3000F1 is a low-mu, all ceramic-and-metal, forced-air cooled, external anode power triode with a maximum plate dissipation rating of 4000 watts. .......
360: Tube DIY Asylum, No OPT's or Speaker Wires Needed (0.00)
Posted by MikeT on 2003-04-26, 04:21:47 (12.238.173.154)
Heck, don't even use OPT's or speaker wires with their inherent sonic degradations. Just put the speakers close enough to the anodes so that you get a spark gap connection. It will look cool too, like .......
361: Tube DIY Asylum, Maybe Not (0.00)
Posted by MikeT on 2003-04-25, 05:29:02 (12.238.173.154)
Think about it in terms of energy storage. A 15 uf cap at 2000V is storing quite a bit of energy, much more than a 220 uf cap at 300V. So, even though it's a small value it's still quite daunting. On .......
362: Tube DIY Asylum, Found The Perfect Cap For You, 15 uf, 5kv :-) (0.00)
Posted by MikeT on 2003-04-24, 21:31:54 (12.238.173.154)
Check this link: http://www.rfparts.com/caps4.html#oil A 15 uf cap, oil filled, rated 5 kv DC. Only $109! .......
363: Tube DIY Asylum, You're Welcome (nt) (0.00)
Posted by MikeT on 2003-04-24, 19:08:00 (12.238.173.154)
nt .......
364: Tube DIY Asylum, Glad I Could Help (nt) (0.00)
Posted by MikeT on 2003-04-24, 19:07:14 (12.238.173.154)
nt .......
365: Tube DIY Asylum, You Can't Pass Current Through Them (0.00)
Posted by MikeT on 2003-04-24, 05:16:18 (12.238.173.154)
Lithium batteries are not rechargeable and you can't pass current through them. You'll need to use either nicad or nickel hydride. I don't know how much current it takes to "trickle charge" one of the .......
366: Tube DIY Asylum, Several Options (0.00)
Posted by MikeT on 2003-04-23, 16:30:16 (12.238.173.154)
I've done business with all of these companies, and they are all good: The Tube Store: www.thetubestore.com Antique Electronics: www.tubesandmore.com Triode Electronics: www.triodeelec.com Parts Expre .......
367: Vintage Asylum, Thanks Joe (0.00)
Posted by MikeT on 2003-04-21, 16:24:13 (12.238.173.154)
I guess I can't run the OP tubes in Class A triode mode at 65 ma each! .......
368: Tube DIY Asylum, Link to Alan Kimmel's Mu-Stage Article (0.00)
Posted by MikeT on 2003-04-21, 15:28:20 (12.238.173.154)
Check out this link: http://www.taosnet.com/f10/mustage.html .......
369: Tube DIY Asylum, Remember Balance...... (0.00)
Posted by MikeT on 2003-04-20, 19:00:52 (12.238.173.154)
Douglas, one more thing to remember is that the level settings in the player are going to have a limited range, like +/- 5 db. So, the amp and speaker combinations you are using need to be within that .......
370: Tube DIY Asylum, Shouldn't Be A Big Deal (0.00)
Posted by MikeT on 2003-04-20, 17:25:50 (12.238.173.154)
All the processing and equalization happens in the player. You can use a 6-channel preamp as you suggest. Companies like DACT even make a 6-gang attenuator. The player itself will have a setup functio .......
371: Vintage Asylum, Need Dynaco PA-060 Ratings (0.00)
Posted by MikeT on 2003-04-20, 09:13:41 (12.238.173.154)
Does anyone know the HV current rating of the Dynaco PA-060 power transformer? I have seen conflicting info. Thanks Mike .......
372: Digital Drive, Thanks I'll Call Next Week (nt) (0.00)
Posted by MikeT on 2003-04-19, 04:58:02 (12.238.173.154)
nt .......
373: Tube DIY Asylum, Thanks Guys - Think I'll Stick With What I've Got (0.00)
Posted by MikeT on 2003-04-19, 04:56:36 (12.238.173.154)
Right now things are sounding pretty good. I'm using a 6BY5 in my linestage and a 5AR4 in the amp. A couple of weeks ago I converted my linestage to a longtail pair with CCS tail, and the amp to balan .......
374: Digital Drive, Anyone Have a Source for CS8412? (0.00)
Posted by MikeT on 2003-04-17, 18:39:14 (12.238.173.154)
This through-hole part is not current production. Anyone know where I can buy some in U.S.? Mike .......
375: Tube DIY Asylum, When Compared to Tube Rectification (0.00)
Posted by MikeT on 2003-04-17, 03:54:12 (12.238.173.154)
I was asking for a comparison of a SS schottky to a tube rectifier, wondering what the advantage was of each approach. I have no experience with SS rectification. I've read that SS diodes are "faster" .......
376: Tube DIY Asylum, Will HV Schottky Make a Difference? (0.00)
Posted by MikeT on 2003-04-16, 14:48:31 (12.238.173.154)
Other than the reduced voltage drop, will the HV schottky diodes now available make a performance difference when compared to tube rectification? Will they result in less noise, deeper bass, etc? ::: .......
377: Tube DIY Asylum, Buy Orange Drop and ICW (0.00)
Posted by MikeT on 2003-04-14, 18:08:43 (12.238.173.154)
No need to use those other caps. For ICW see: http://www.diycable.com/catalog/products/parts_icw.htm I have not used them but I'm going to now. .......
378: Tube DIY Asylum, Reference Info FYI (0.00)
Posted by MikeT on 2003-04-14, 16:35:45 (12.238.173.154)
Hello Ron, I'm not an Ultrapath expert so I can't answer your questions, but I've ben doing some research on this myself and came across the following: http://www.tubecad.com/april_may2001/page41.html .......
379: Digital Drive, But Is It Worth Tweaking.......... (0.00)
Posted by MikeT on 2003-04-13, 19:34:40 (12.238.173.154)
Thanks for the info gents. I know that the latest and greatest Pioneer players like the DV47ai use "Legato Pro" which I understand is upsampling. The real crux of what I'm trying to figure out is whe .......
380: Tube DIY Asylum, I'm Pretty Close Now (0.00)
Posted by MikeT on 2003-04-13, 16:15:05 (12.238.173.154)
Right now I'm running a pair of 5687's with individual cathode resistors in a balanced configuration. They are driving EL34's in push-pull, using an ST70 chassis. I've taken out the ST70 driver board .......
381: Digital Drive, Sounds Like Upsampling to Me (0.00)
Posted by MikeT on 2003-04-12, 09:17:39 (12.238.173.154)
Thanks Eduardo. I found this info on a web site. It sounds like it's 16 to 20 bit upsampling. Hi-bit Legato Link Conversion The "Hi-bit Legato Link Conversion" technology applied in the PDR-D7 combine .......
382: Tube DIY Asylum, Yep, It's An Input Stage (0.00)
Posted by MikeT on 2003-04-11, 17:40:08 (12.238.173.154)
I wanted to go balanced as early as possible. I first tried an Allied IT without shielding, and learned why they invented mu metal. Then I tried a split load phase splitter and learned about why you n .......
383: Tube DIY Asylum, Good Point, Thanks (0.00)
Posted by MikeT on 2003-04-11, 17:35:46 (12.238.173.154)
OK, it's like when you use a CCS for a plate load, the plate voltage is whatever it is based on the grid voltage; so long as there is enough difference for the CCS to regulate you are good to go. ::: .......
384: Digital Drive, What Is Pioneer Legato Link? (0.00)
Posted by MikeT on 2003-04-11, 17:29:20 (12.238.173.154)
I have a DV37 DVD player, and there's no explanation I can find for what Legato Link means. Can someone help? Thanks. .......
385: Tube DIY Asylum, I Think I've Got It Guys - Here's A Playback (0.00)
Posted by MikeT on 2003-04-11, 13:19:07 (12.238.173.154)
OK, now I think I get it. The pair is intended to be capable of being a DC amp, like a differential amp. So, you want the grid at 0V. Now we take a tube like the 12SN7. Let's say we have a B+ of 400V, .......
386: Tube DIY Asylum, A Couple More Questions (0.00)
Posted by MikeT on 2003-04-10, 19:34:58 (12.238.173.154)
OK, if you use a negative supply, I can't see how the grid will ever be negative with respect to the cathode, so I don't see how the tube ever gets biased. Once again, I show my ignorance here; I must .......
387: Tube DIY Asylum, Re: Balancing a Long-Tail Pair (0.00)
Posted by MikeT on 2003-04-10, 07:50:18 (12.238.173.154)
Hello James. The CCS is in the cathode. I have seen many versions of a long-tail pair, some with a negative voltage and some without. Based on what I've seen I can't for the life of me figure out how .......
388: Tube DIY Asylum, Balancing a Long-Tail Pair (0.00)
Posted by MikeT on 2003-04-10, 06:47:49 (12.238.173.154)
In my latest experiment, I have a long-tail pair using a 12SN7 with a CCS load and a single-polarity supply. What is the best way to balance the stage? On one channel I have about a 1V difference, but .......
389: Bottlehead Forum, Got It Working, Thanks (0.00)
Posted by MikeT on 2003-04-07, 12:48:29 (12.238.173.154)
Sorry about all the confusion. I used the CF version, (with NPN transistors!) and biased it to the B+, and eveything works. Thanks. .......
390: Bottlehead Forum, It's PNP Transistors! (0.00)
Posted by MikeT on 2003-04-06, 11:53:28 (12.238.173.154)
After a good night's sleep it all makes sense. It's PNP transistors, so everything has to be referenced to a negative supply. I'm running single ended , so I was not biasing from a high enough voltage .......
391: Bottlehead Forum, Why A Negative Voltage? (0.00)
Posted by MikeT on 2003-04-05, 21:03:36 (12.238.173.154)
Can you give me a bit more explanation of the theory? I feel like a babbling idiot right now! I've read the C4S manual and looked at the figures and my head is swimming; it's been a long day. I have .......
392: Bottlehead Forum, Hum/Buzz With C4S Current Sink? (0.00)
Posted by MikeT on 2003-04-05, 20:14:08 (12.238.173.154)
I have been running a long tail pair with a cathode resistor for quite a while and today I decided to switch to a C4S current sink. I set it up for 16 ma current, with about 3 ma bias for the LED's. N .......
393: K&K Audio / Lundahl Transformers, Kevin: Need Recommendation for Line Input Xfmr (0.00)
Posted by MikeT on 2003-03-29, 13:12:35 (12.238.173.154)
Hello Kevin. I need a recommendation for a line input transformer to a balanced linestage. The entire chain after this transformer will be balanced. It will be driving the grids of the first tubes in .......
394: Tube DIY Asylum, The Force Is Strong In This One (0.00)
Posted by MikeT on 2003-03-29, 12:51:48 (12.238.173.154)
Right you are Paul. I have a separate power supply for my linestage, on a double-shielded power tether that's about three feet long. I had to move the linestage box about 2 ft. from the PS transformer .......
395: Tube DIY Asylum, Hum Pickup From Interstage Transformers (0.00)
Posted by MikeT on 2003-03-28, 13:06:52 (12.238.173.154)
Is hum pickup from interstage transformers a common problem? If so, what is the mechanism, and how do you combat it? How do the better transformer manufacturers address the problem? Is mu-metal or oth .......
396: Tube DIY Asylum, Re: What To Do With Unused CT of Interstage Xfmr (0.00)
Posted by MikeT on 2003-03-24, 11:05:41 (12.238.173.154)
It sounds the way it did before I did the grounding, just lower level and with no hum. How did you learn about transformers. Is there a text you can refer me to? My intuition about them is all wrong. .......
397: Tube DIY Asylum, Re: What To Do With Unused CT of Interstage Xfmr (0.00)
Posted by MikeT on 2003-03-24, 09:29:22 (12.238.173.154)
Yep, I really grounded it, both the CT and the - side. There were no negative affects as far as I can tell, except reduced drive. I'm driving a 5687 with a 5687. I must admit I'm really ignorant when .......
398: Tube DIY Asylum, What To Do With Unused CT of Interstage Xfmr (0.00)
Posted by MikeT on 2003-03-24, 06:58:53 (12.238.173.154)
I have a Hammond SE-PP transformer I'm using as an SE-SE interstage. It turns out the center tap on the secondary was coupling hum into the circuit when I let it float. I grounded it and that fixed th .......
399: Tube DIY Asylum, It's On The Supertex Web Site (0.00)
Posted by MikeT on 2003-03-20, 13:45:39 (12.238.173.154)
If you go to this link, the data sheet says to use the DN3535 or DN4545 for new designs. http://www.supertex.com/pdf/datasheets/DN2540.pdf Mike .......
400: Tube DIY Asylum, Sorry Douglas and Gary: I Stand Corrected! (0.00)
Posted by MikeT on 2003-03-19, 11:07:24 (12.238.173.154)
Sorry for any confusion my error might have caused. That's what I like about this forum - access to experts! Mike .......
401: Tube DIY Asylum, Re: Gary Pimm: Please Verify How R is Determined (0.00)
Posted by MikeT on 2003-03-18, 20:17:58 (12.238.173.154)
Hello Douglas. I think for the battery bias case you subtract the turn-on voltage from the bias voltage, and use the difference to calculate the resistance value. .......
402: Tube DIY Asylum, Gary Pimm: Please Verify How R is Determined (0.00)
Posted by MikeT on 2003-03-18, 18:29:51 (12.238.173.154)
Gary, to determine R as you have shown, I'm assuming you divide the turn-on voltage of the FET by the desired current; for example, for a 4V turn-on and 10 ma current R would be 4V/.01A, or 400 ohms. .......
403: Bottlehead Forum, Thanks Gents (nt) (0.00)
Posted by MikeT on 2003-03-18, 18:24:31 (12.238.173.154)
no text .......
404: Tube DIY Asylum, What About Another FET? (0.00)
Posted by MikeT on 2003-03-18, 07:16:22 (12.238.173.154)
Does anyone know if another MOSFET can be used? For example, Digi-Key carries the IR IRFBC20, which is a 600V, 4.4 ohm, 2.2 amp MOSFET, for $1.23 each. See this link for specs: http://www.irf.com/prod .......
405: K&K Audio / Lundahl Transformers, Push-Pull Without a Center Tap on Primary (0.00)
Posted by MikeT on 2003-03-17, 16:32:19 (12.238.173.154)
I realize this is somewhat off-topic, but you guys are transformer experts, and I need your help. I've been trying to understand push-pull and I get wrapped around the axle. I cannot figure out the fo .......
406: Bottlehead Forum, Phil Sieg Parafeed Push-Pull Amp? (0.00)
Posted by MikeT on 2003-03-17, 16:01:20 (12.238.173.154)
I've seen a thread on the Tube DIY board that said Phil Sieg has built a parafeed push-pull amp. Can anyone point me to the schematic? Thanks Mike .......
407: Tube DIY Asylum, Dumb Question About Symmetric Driver Stage (0.00)
Posted by MikeT on 2003-03-12, 08:49:34 (12.238.173.154)
I want to build a symmetric driver stage using two 5687's and a Hammond interstage transformer. The primary of the transformer does not have a center tap. (It can handle 5 "music watts" worth of curre .......
408: Tube DIY Asylum, Bleeders (0.00)
Posted by MikeT on 2003-03-09, 08:53:22 (12.238.173.154)
FYI, I agree about bleeders. I have them, and always use them, standard, without question. Ten years or so ago, doing a TV repair, I got zapped by a cap that had recharged itself, after power was remo .......
409: Tube DIY Asylum, Here's What I Found (0.00)
Posted by MikeT on 2003-03-08, 19:35:54 (12.238.173.154)
Well, it turns out that my problems was due to the fact that I paralleled the 6N1P's. I am running a 300 ohm cathode resistor bypassed by 100uf. With one half of the tube in use I get 280V B+ with 4V .......
410: Tube DIY Asylum, What In The World Is Wrong With My PS? (0.00)
Posted by MikeT on 2003-03-06, 22:10:00 (12.238.173.154)
I am stumped. I've got an L-C-L-C supply that's putting out way too much voltage: PT: Hammond 272BX, 300-0-300, 100ma Rectifier: 6BY5G Inductors: Triad C7X, 90 ma, 10H, 270 ohms Caps: Panasonic 220 uf .......
411: Digital Drive, CDP Output Filtering and Noise (0.00)
Posted by MikeT on 2003-02-25, 05:28:44 (12.238.173.154)
I have a Sony SCD-CE775 CD player. I have removed all the muting, filtering, and op-amp output circuitry and I am feeding the outputs directly from the DAC, which are voltage outputs. I'm getting plen .......
412: Tube DIY Asylum, Re: 7N7 Please help on 6SN7 cathode follower (0.00)
Posted by MikeT on 2003-01-26, 16:14:20 (12.238.173.154)
The tube is not conducting, probably because the grid is not biased properly. Try this. Let's set the tube up to draw 5 ma, with your 400V supply and 30K cathode resistor. You'll get about 150V across .......
413: Tube DIY Asylum, Re: Dyna ST-70 bias (0.00)
Posted by MikeT on 2003-01-26, 10:54:22 (12.238.173.154)
See this link for ST70 troubleshooting: http://www.triodeel.com./trouble.html .......
414: Tube DIY Asylum, Re: Soooo.... (0.00)
Posted by MikeT on 2003-01-25, 21:43:00 (12.238.173.154)
No kiddin...... I didn't know that about the 470's. If I upgrade iron the first ones I think I'll try are the Lundahls. I've got quite a bit of playing around to do first though. Go Nittany Lions! ::: .......
415: Tube DIY Asylum, Re: Soooo.... (0.00)
Posted by MikeT on 2003-01-25, 15:45:09 (12.238.173.154)
I thought I'd stick with the Dyna OPT's. I figured they were sized properly. What do you suggest? .......
416: Tube DIY Asylum, ST70 Mod Update - And Thanks To All Who Helped (0.00)
Posted by MikeT on 2003-01-25, 08:46:02 (12.238.173.154)
Last week I posted about a mod I was doing to my ST70, driving the EL34's with a Allied IT. I was having drive problems. Here's what's been happening: a. I had some success with a choke loaded power s .......
417: Tube DIY Asylum, Darn It, I Can't Run 6N1P at 375, I'll Fix it and Update! (0.00)
Posted by MikeT on 2003-01-18, 17:46:29 (12.238.173.154)
So as I'm listening, I remember the plate of the second 6N1P is at 375 VDC. Not so good long term since the tube has a max rating of 250V at the plate. So, I'll convert the PS to LCLC, which gives me .......
418: Tube DIY Asylum, It's Working, Thanks, Not Your Father's ST-70! (0.00)
Posted by MikeT on 2003-01-18, 17:20:09 (12.238.173.154)
First of all, I want to thank everyone for the advice. I came up with what may be an off-the-wall topology and you guys got me straight. I wanted to go as simple as possible, but no simpler! I finally .......
419: Tube DIY Asylum, Re: It's ALL Your Fault Lynn! :-) Please Read This Guys (0.00)
Posted by MikeT on 2003-01-18, 16:40:48 (12.238.173.154)
Thanks for the insight Paul. I did not know that unbypassed cathode resistors on the EL34's would affect gain that dramatically. I did not bypass the EL34 cathode resistors. Also, to clarify, I had a .......
420: Tube DIY Asylum, I Love Tough Love! (0.00)
Posted by MikeT on 2003-01-18, 07:14:37 (12.238.173.154)
Mikey, please read what I just posted. Loading the 12AX7 with the IT was where I was when I did the post. Before that I had tried a 12SN7 with cap coupling, then tried a 6N1P, then tried a 12AX7, and .......
421: Tube DIY Asylum, It's ALL Your Fault Lynn! :-) Please Read This Guys (0.00)
Posted by MikeT on 2003-01-18, 07:07:31 (12.238.173.154)
Of all the posts, Lynn Olson's was the funniest to me - it made me laugh out loud. I'm into tube electronics - how can my feelings be hurt? All my EE friends from work come over and laugh at me! (What .......
422: Tube DIY Asylum, Help With PP Amp, I'm Stumped! (0.00)
Posted by MikeT on 2003-01-17, 18:06:02 (12.238.173.154)
I've taken an ST-70 that works with the Welborne mod and done the following: 1. Set the EL34's up for self bias with a 500 ohm cathode resistor to ground on each EL34 tube. 2. Removed the driver board .......
423: Tube DIY Asylum, Re: Check This Out and Then Let's Converse (0.00)
Posted by MikeT on 2002-12-26, 21:05:29 (12.238.173.154)
OK Brian, I wanted to make sure you knew about Joe's site because it has a ton of info about Dynaco products. I don't know if the units you have are working or not, but I'll assume they are. (If they .......
424: Tube DIY Asylum, Check This Out and Then Let's Converse (0.00)
Posted by MikeT on 2002-12-26, 10:25:52 (12.238.173.154)
Hello Brian I just restored an ST70 a few months ago. Check out this web site concerning restoring Dynaco amps and preamps. It's run by Joe Curcio, who is great to deal with and a straight shooter. h .......
425: Tube DIY Asylum, Thanks Gents I Think I'm OK (0.00)
Posted by MikeT on 2002-12-18, 17:04:01 (12.238.173.154)
I get a thunk, but no ringing and singing, so it sounds like I'm OK. The tubes are Sylvania 12SN7 JAN tubes. I wonder if RCA's sound better......... Thanks Mike .......
426: Tube DIY Asylum, Is This The Same as the Lucent Fist-Bang Test? (0.00)
Posted by MikeT on 2002-12-18, 15:58:28 (12.238.173.154)
Seriously, I'm just trying to figure out if I have a problem. If I tap the tubes I definitely hear a thump from my speakers. I don't know if this is normal or not. Of course, I'm tapping with a 20-lb. .......
427: Tube DIY Asylum, Is The Thump Test Valid To Find Microphonics (0.00)
Posted by MikeT on 2002-12-18, 12:57:14 (63.120.210.34)
I've got a couple of 12SN7's in a line stage. Whenever I tap the chassis (lightly), touch cables, or change the rotary switches I get loud thumps through the speakers. Is this normal, or are the tubes .......
428: Tweakers' Asylum, See www.welbornelabs.com (0.00)
Posted by MikeT on 2002-12-14, 20:10:28 (12.238.173.154)
There is a +/- 20 VDC power supply kit available on the Welborne Labs site. .......
429: Tweakers' Asylum, Cambridge D300 SE SMT or Through-Hole? (0.00)
Posted by MikeT on 2002-12-09, 14:04:19 (65.94.224.228)
Anyone know if this CDP uses through-hole parts, or SMT. Thanks .......
430: Tube DIY Asylum, I Figured the Welborne Driver Was Pretty Good..... (0.00)
Posted by MikeT on 2002-12-03, 19:13:22 (12.238.173.154)
The Welborne driver is a concertina followed by a mu stage. This seems like a pretty good topology. Do I really need a new driver stage? If so, why? .......
431: Tube DIY Asylum, I'm Already Running Triode Mode :-) (0.00)
Posted by MikeT on 2002-12-03, 14:01:23 (63.120.210.34)
Thanks Dave - I must not have been clear; I'm already running in triode mode with the EL34's. I think if I do the 6B4 thing I'll move everything to a bigger chassis, use a new filament transformer for .......
432: Tube DIY Asylum, Convert ST70 to 6B4G? (0.00)
Posted by MikeT on 2002-12-03, 12:18:59 (63.120.210.34)
I currently have an ST70 with the Welborne mod, and I'm running Svetlana EL34's in triode mode. I've been wondering if a DHT will sound demonstrably better. Should I bother to convert to 6B4G? Will I .......
433: DIY HiFi Forum, Thanks Guido Re: Info Needed Re. XO1 (0.00)
Posted by MikeT on 2002-12-02, 07:46:14 (63.120.210.34)
That's what I needed! I'll be ordering an XO1 shortly! Mike .......
434: DIY HiFi Forum, Info Needed Re. XO1 (0.00)
Posted by MikeT on 2002-12-01, 19:30:34 (12.238.173.154)
I've been looking for more information concerning the Tent XO1. Is this a VCXO, TCXO, or some other type of oscillator? What is it's output: clipped sine wave, TTL, CMOS, etc.? What is the input volta .......
435: Welborne Labs, Re: Converting ST-70 to 6B4 Tubes (0.00)
Posted by MikeT on 2002-11-25, 15:00:23 (65.94.224.228)
Will do. I'm sneaking up on it, trying to psych myself up to do it. Right now I'm leaning towards two new filament transformers to feed the 6B4's and mounting eveything in a new chassis. .......
436: Welborne Labs, Thanks Ron (nt) (0.00)
Posted by MikeT on 2002-11-22, 09:27:57 (63.120.210.34)
nt .......
437: Tweakers' Asylum, Re: Tweaking I Did This Weekend and Op Amps (0.00)
Posted by MikeT on 2002-11-21, 17:00:09 (12.238.173.154)
Hello Nicolas. I have an SCD CE-775. The mods I did are intricate, since many of the components are surface mount. Basically, I removed quite a few resistors, capacitors, and transistors, after studyi .......
438: Welborne Labs, Converting ST-70 to 6B4 Tubes (0.00)
Posted by MikeT on 2002-11-20, 11:05:24 (63.120.210.34)
I have an ST 70 with the Welborne mod package and I'm thinking of converting it to 6B4G tubes. I'm currently running EL34's in triode mode. First, is it worth it, will I hear much difference? If so, h .......
439: Tweakers' Asylum, Re: Tweaking I Did This Weekend and Op Amps (0.00)
Posted by MikeT on 2002-11-20, 10:46:47 (63.120.210.34)
Hello Larry. I did not do all the mods I wrote about one at a time, so I really can't judge how much the ground mod changed things. I also don't have a scope so I can't say how much the noise floor ch .......
440: Tweakers' Asylum, Tweaking I Did This Weekend and Op Amps (0.00)
Posted by MikeT on 2002-11-18, 11:43:39 (63.120.210.34)
Allen, you are definitely correct about the op amps. I did a great deal of mods to the analog output stage this weekend: - I removed all the muting transistors, bypass caps, resistors, and filter comp .......
441: Tweakers' Asylum, Can You Give Me Your Impressions of the Tent Clock? (0.00)
Posted by MikeT on 2002-11-17, 05:44:10 (12.238.173.154)
Thanks Allen, I'm always trying to be the "frugal tweaker." What kind of difference did the Tent clock make? Right now the top end seems brittle and harsh, especially during complex passages - but tha .......
442: Tweakers' Asylum, Are These Clock Specs Good Enough For a CDP? (0.00)
Posted by MikeT on 2002-11-16, 19:24:01 (12.238.173.154)
I've found a programmble clock oscillator for about $7 at Digi-Key. Here are the specs: Jitter: 40 psec typ, 50 psec max, 1 sigma Peak-to-peak jitter: 100 psec typ, 250 psec max Stability: 25 ppm Rise .......
443: Tube DIY Asylum, Thanks for the Info Gents, Good Advice! (nt) (0.00)
Posted by MikeT on 2002-11-05, 05:58:06 (12.238.173.154)
nt .......
444: Tube DIY Asylum, Re: Depends on who rated it ... (0.00)
Posted by MikeT on 2002-11-03, 09:17:13 (12.238.173.154)
Thanks for the info Paul. I'm talking here about Hammond 125 ESE xfmrs. I'm thinking of treading lightly into the world of SET's and this seems like a good start. I've got a pair of Nautilus 803 speak .......
445: Tweakers' Asylum, No Need To Mod SCD CE-775 PS Diodes? (0.00)
Posted by MikeT on 2002-11-03, 08:53:11 (12.238.173.154)
I've been looking at the SCD CE-775 schematic to figure out what mods I want to do. The op amps on the audio board are powered by +/- 7 VDC. This section of the power supply that supplies the audio bo .......
446: Tube DIY Asylum, How Much Margin Is Needed for OPT Current? (0.00)
Posted by MikeT on 2002-11-02, 08:00:28 (12.238.173.154)
If an OPT is rated for 80 ma, can it be operated at an 80 ma bias point, Class A, or does the current need to be derated? If so, what is a rule of thumb for the derating? Thanks Mike .......
447: Tube DIY Asylum, Is 1/2" Spacing Between 2A3 Tubes OK (nt) (0.00)
Posted by MikeT on 2002-10-13, 15:35:26 (12.238.173.154)
nt .......
448: Tube DIY Asylum, Re: How did you decided on the order? (0.00)
Posted by MikeT on 2002-10-09, 17:39:54 (12.238.173.154)
Thanks for the kudos Taz! The order of the connections does not matter. What was key to me was to run the grounds separately from each "subsystem" in the circuit, as described in the list. This method .......
449: Tube DIY Asylum, Grounding and Power Filtering - What Worked For Me (0.00)
Posted by MikeT on 2002-10-06, 07:34:23 (12.238.173.154)
I was having a problem with hum and buzz in a home-brew line stage that was giving me fits. The problem was getting worse with time. It turned out that there was a bad PCB trace on my filament regulat .......
450: Tube DIY Asylum, The Hum Is Fixed - Climbing the Learning Curve (0.00)
Posted by MikeT on 2002-09-24, 20:29:13 (12.238.173.154)
A few of you have tryed to help me fix the hum problem in my linestage. I've been fighting it for weeks, after living with it for months, as it slowly got worse. Well, it turns out that there was a ha .......
451: Tube DIY Asylum, Re: Can A PT Make a Linestage Hum/Buzz? (0.00)
Posted by MikeT on 2002-09-21, 15:20:23 (12.238.173.154)
Signal and chassis ground are connected at one point. The PS is in a separate chassis from the preamp tubes. I run an 18 ga. ground from the PS to the preamp chassis. I tie everything to that ground a .......
452: Tube DIY Asylum, Can A PT Make a Linestage Hum/Buzz? (0.00)
Posted by MikeT on 2002-09-21, 08:36:50 (12.238.173.154)
Can a power transformer make a linestage hum and buzz? I've got a problem and the only thing I have not tried yet is to change out the power transformer. I know it's not the wiring, tubes, cold solder .......
453: Tube DIY Asylum, Tried 'Em All, Still Buzzin' (0.00)
Posted by MikeT on 2002-09-16, 21:10:22 (12.238.173.154)
I grounded the filament supply negative side to chassis, cut the input grounds loose, and it's still buzzing. I'll try more stuff tomorrow. When I cut the ground on the inputs loose the buzz in one ch .......
454: Tube DIY Asylum, Filters in the Ground Circuit (0.00)
Posted by MikeT on 2002-09-16, 10:22:03 (63.120.210.34)
Paul, in your post you refer to a signal ground and I'm trying to understand what that means. I've looked at several grounding schemes where an RC filter is put in the circuit between "signal ground" .......
455: Tube DIY Asylum, More Info Tiny Daddy and Ken...... (0.00)
Posted by MikeT on 2002-09-15, 19:50:29 (12.238.173.154)
Ken, I'm using stepped attenuators and they're pretty well grounded. Good thought though. Tiny Daddy: The buzz is fairly low level. Only apparent during quiet passages. If it's EMI from the PT, then t .......
456: Tube DIY Asylum, Need Help with Hum/Buzz I'm Out of Ideas (0.00)
Posted by MikeT on 2002-09-15, 18:10:02 (12.238.173.154)
Today I decided to find the source of the hum/buzz in my system. I've isolated it to the linestage. I rebuilt the linestage and PS for preamp. The PS is in a separate chassis. I have swapped interconn .......
457: Tube DIY Asylum, First Theory Then Reality (0.00)
Posted by MikeT on 2002-09-08, 16:20:02 (12.238.173.154)
Yep, I agree with you. First learn the theory from books and teachers and then learn about things in the real world. No problem with that. I'd like to do both though, and tubes are no longer taught! I .......
458: Tube DIY Asylum, So Then What Good is This Tube (Rhetorical) (0.00)
Posted by MikeT on 2002-09-08, 11:27:08 (12.238.173.154)
This is the kind of thing that's always puzzled me in my quest for tube knowledge. If you take a tube like the 6N1P that has a pretty good rep and is in current production, I feel like it's a tease to .......
459: Tube DIY Asylum, Tube Data Sheet Teasers, or What Am I Missing? (0.00)
Posted by MikeT on 2002-09-08, 09:12:15 (12.238.173.154)
I'm looking at the data sheet for a 6N1P. It states that the max anode current is 250V. The tube curves show grid voltages from 0 to -14V. The way I read this is that any grid voltage above 4V is basi .......
460: Tube DIY Asylum, See This Link at Goldpoint (0.00)
Posted by MikeT on 2002-09-08, 07:27:43 (12.238.173.154)
http://www.goldpt.com/pre.html .......
461: Tube DIY Asylum, Please Help Set Expectations Re. Hum/Noise (0.00)
Posted by MikeT on 2002-09-07, 07:23:46 (12.238.173.154)
I consider myself a rookie to the world of tubes. I built a Foreplay and then my own home-brew mu-stage preamp over the course of the last year, and also have rebuilt an ST70 using the Welborne Labs m .......
462: Welborne Labs, Thanks Ron, and Some Questions (0.00)
Posted by MikeT on 2002-09-05, 04:42:52 (12.238.173.154)
Thanks Ron, that's the advice I was looking for. A question about the mod: Can I eliminate the two input caps C10 and C18, or change them out for bigger values? Are they required for stability? ::: T .......
463: Tube DIY Asylum, Thanks For The Comments (0.00)
Posted by MikeT on 2002-09-05, 04:38:52 (12.238.173.154)
My plan is to try to find the hum culprit on what I have. .......
464: Tube DIY Asylum, How Good is a Modified ST70? (0.00)
Posted by MikeT on 2002-09-03, 17:58:15 (12.238.173.154)
My first entry into the world of tube amps has been to rebuild an ST70 using the Welborne mod. I've completed the project and the amp works fine into my N803s, for the most part. I've got a hum proble .......
465: Welborne Labs, Opinions Please: How Good is a Modified ST70? (0.00)
Posted by MikeT on 2002-09-02, 08:16:34 (12.238.173.154)
My first entry into the world of tube amps has been to rebuild an ST70 using the Welborne mod. I've completed the project and the amp works fine into my N803s, for the most part. I've got a hum proble .......
466: Tube DIY Asylum, Re: ST 70 Hum After Things Heat Up - Power Xfmr? (0.00)
Posted by MikeT on 2002-09-02, 07:58:54 (12.238.173.154)
Thanks for the help Gordon. I'm going to implement some of Quest's suggestions and see what happens. I suspect it is the power tranny but I think it could also be bad solder joints that heat up and ca .......
467: Tube DIY Asylum, Re: Check the following: (0.00)
Posted by MikeT on 2002-09-02, 07:55:55 (12.238.173.154)
Quest, thanks for the advice. Here's some info: - The Welborne Labs mod includes a capacitor replacement. - I'm looking at the grounding again to see if I missed anything. - I'm also checking all the .......
468: Tube DIY Asylum, ST 70 Hum After Things Heat Up - Power Xfmr? (0.00)
Posted by MikeT on 2002-08-29, 21:13:11 (12.238.173.154)
I bought an "original" ST70 (A470 OPT's, PA060 PT) and re-built it completely. I used the Welborne Labs mod, replaced all the tube sockets and rewired everything fresh. I get an audible hum that appea .......
469: Tube DIY Asylum, The Guy Is Such a Splendid Piece of Work! (0.00)
Posted by MikeT on 2002-07-30, 10:32:13 (63.120.210.34)
I was just browsing the Angela web site for some trannies and came across this. Steve is pretty proud of his rep I guess; he's posted this for all the world to see. What a piece of work! I'm grinning .......
470: Tube DIY Asylum, Re: Now you've got that sorted (0.00)
Posted by MikeT on 2002-07-18, 17:57:27 (12.238.172.151)
Thanks. I've got that already. I'm about the try again, so I've asked my wife to brush up on her CPR and I've got 911 queued up! .......
471: Tube DIY Asylum, Stupid Is As Stupid Does (0.00)
Posted by MikeT on 2002-07-18, 17:30:36 (12.238.172.151)
Another case of brain freeze for all the world to see. They did indeed burn up quick. Thanks guys. Mike .......
472: Tube DIY Asylum, I'm Stumped: Why Did I Smoke The Resistors? (0.00)
Posted by MikeT on 2002-07-18, 16:47:45 (12.238.172.151)
I have (had) a line stage using two 12SN7s as a mu follower with a 400 VDC B+ supply. I'm also using a 12.6 VDC regulated filament supply. When I went to raise the filament supply to about 40V above g .......
473: Tube DIY Asylum, What's the Theory? (0.00)
Posted by MikeT on 2002-06-26, 05:35:06 (12.238.172.151)
Can you explain why both are needed? I thought that if you have a regulated B+ (constant voltage) that as a result the current would be constant too, everywhere in the circuit there is a fixed load li .......
474: Tube DIY Asylum, Re: Plea for Valve article (0.00)
Posted by MikeT on 2002-06-25, 09:12:21 (63.120.210.34)
I'm using four IXYS current regs in my DIY preamp, but it hisses. I'm not sure yet what the source of the hissing is so I'm in the process of taking out the IXYS and using the C4S. The resistors I nee .......
475: Tube DIY Asylum, CCS Vs. Regulated Supply - Either One or Both? (0.00)
Posted by MikeT on 2002-06-23, 15:44:58 (12.238.172.151)
If you have a regulated B+ supply, is a CCS still needed? Any reason to use both at the same time? .......
476: Bottlehead Forum, Can I Run C4S At More Than 2 Ma Bias? (0.00)
Posted by MikeT on 2002-06-21, 21:41:46 (12.238.172.151)
Is there an advantage to running the C4S LED's at a bias greater than 2 ma? Any down side? I need to source/sink 5-10 ma with a B+ of 400V. I know I have to drop the voltage to 300 max, but are there .......
477: Tube DIY Asylum, Re: It depends... (0.00)
Posted by MikeT on 2002-06-13, 19:29:34 (12.238.172.151)
Thanks for the guidance Gary. I have indeed found Duncan's PS designer software to be very handy. Mike .......
478: Tube DIY Asylum, Re: It depends... (0.00)
Posted by MikeT on 2002-06-13, 10:46:03 (63.120.210.34)
I'll use EL34's, class A, triode, and experiment with ultralinear connections, but always class A. I also plan to experiment with KT66's at some point. .......
479: Tube DIY Asylum, Thanks for the Help Folks (0.00)
Posted by MikeT on 2002-06-12, 15:54:19 (63.120.210.34)
I plan to build something close assuming the load line is straight rather than elliptical and then I'll tweak until I like the sound. That's why DIY is fun - custom sound! .......
480: Tube DIY Asylum, Guidelines for Sizing Amp PS (0.00)
Posted by MikeT on 2002-06-12, 15:27:07 (63.120.210.34)
I want to build a PP amp. Do I size the current rating of the PS based on the quiescent setting or the max current swing I expect the amp to deliver based on the load line? What are the guidelines? Al .......
481: Tube DIY Asylum, EL34 SE Operating Point: What Am I Missing? (0.00)
Posted by MikeT on 2002-06-09, 08:36:42 (12.238.172.151)
I'm about to build my first tube amp, and I've been researching the EL34 to use in a SET design. (I'd like to go relatively inexpensive first so I can see if I like it before jumping into a $200 300B .......
482: Tube DIY Asylum, Thanks Kurt (0.00)
Posted by MikeT on 2002-05-29, 21:02:45 (12.238.172.151)
Kurt, I remember finding your grounding info last year and it really helped me realize that ground is a signal path in the real world unlike what they taught in EE51 at Penn State. Thanks. Also, it's .......
483: Tube DIY Asylum, My First SET Amp: What's Your Favorite Tube (0.00)
Posted by MikeT on 2002-05-24, 17:34:30 (12.238.172.151)
300B? EL34? 2A3? Other? What's your favorite? .......
484: Tube DIY Asylum, Re: Guidelines for PA headroom (0.00)
Posted by MikeT on 2002-05-22, 18:57:21 (12.238.172.151)
Thanks gents! Britney's peaks are just fine the way they are, maybe too fine, and T-Rex will have to soft-shoe it. It's music I'm after! Interesting, but when I find myself listening at a comfortable .......
485: Tube DIY Asylum, Guidelines for PA headroom (0.00)
Posted by MikeT on 2002-05-22, 13:42:27 (63.120.210.34)
I've got Nautilus 803 speakers (90 db, 8 ohms nominal, 3 ohms minium). I listen mostly to classical music and jazz. I find that 90 db is loud when I use the Radio Shack SPL meter. Usually I'm listenin .......
486: Tube DIY Asylum, Update on My Homebrew Preamp (0.00)
Posted by MikeT on 2002-05-11, 09:04:26 (12.238.172.151)
Over the past month or so I've been working on a unity-gain linestage, and have posted several messages for advice on tubes, PS configs, etc. As a follow-up to the all the folks who've rendered aid, h .......
487: Tube DIY Asylum, So Would An Unregulated Filament Be Noisy? (0.00)
Posted by MikeT on 2002-05-03, 16:37:38 (12.238.172.151)
You know I like the CRC or CLC idea. Would an unregulated filament be appreciably more noisy than a regulated one? Mike .......
488: Tube DIY Asylum, Hot Time with My Filament Reg - Is This Normal? (0.00)
Posted by MikeT on 2002-05-02, 09:39:27 (63.120.210.34)
I recently modified my Foreplay pretty heavily. I built an outboard HV supply CLCLC 360V, and a regulated filament supply built into the FP chassis. I then changed to octal sockets and am running two .......
489: Tube DIY Asylum, Re: Need Advice on Where to Buy 6SN7 (0.00)
Posted by MikeT on 2002-05-01, 20:09:37 (12.238.172.151)
Good idea. I was just checking out how hot my 6.3V regulator is running. I have a 30W heat sink that's pretty hot to the touch. So, running at 12.6 VDC is attractive. Where do you buy the 12SN7's? ::: .......
490: Tube DIY Asylum, Need Advice on Where to Buy 6SN7 (0.00)
Posted by MikeT on 2002-05-01, 19:13:06 (12.238.172.151)
I just got done building a preamp, and I bought two Sovtek 6SN7's and near as I can tell they are both bad. One is microphonic and the other is very microphonic and it hums. So, I need a recommendatio .......
491: Tube DIY Asylum, Re: Chassis and Metal Work (0.00)
Posted by MikeT on 2002-04-27, 18:32:47 (12.238.172.151)
Check out Online Metals: http://www.onlinemetals.com/ You can buy the top plate in aluminum or copper from them and then visit any home center or woodworker's store to buy wood for the box. Another ap .......
492: General Asylum, John : What a Great Gesture! (0.00)
Posted by MikeT on 2002-04-18, 18:42:42 (12.238.172.151)
Man, what a great thing to do. I'm grinning ear to ear. .......
493: Tube DIY Asylum, Here's The Plan (0.00)
Posted by MikeT on 2002-04-18, 05:27:32 (12.238.172.151)
And the winner is...... Regulated 6.3 VDC filament via separate transformer, 2000 uf FW Rectifier using 6BY5GA CLCLC filter, first capacitor 4.7 uf, the rest 220 uf, all 450V, should give me 340-360 V .......
494: Tube DIY Asylum, Can You Suggest a Lower Gain Alternative to CF (0.00)
Posted by MikeT on 2002-04-16, 14:22:49 (63.120.210.34)
Lew, I'm not hung up on the CF, but I don't need much gain, say 6 db max. Can you recommend a better-sounding configuration but with lower gain? Also, do you have any experience with the 6922? ::: TOP .......
495: Tube DIY Asylum, Help Me Blue Sky a Preamp Design (0.00)
Posted by MikeT on 2002-04-13, 19:09:23 (12.238.172.151)
I just bought an Allied 270-0-270 power tranny, some 220 uf 450V Panasonic caps, two 10H chokes, and two 6BY5 dampers. I've got a really sensitive amp and I'm thinking about a unity gain preamp. I don .......
496: Bottlehead Forum, How Did You Pick the Operating Point? (0.00)
Posted by MikeT on 2002-04-10, 08:18:28 (63.120.210.34)
Thanks for the comments. I have a question though. When I look at the 12AU7 tube curves I find that an operating point around 10 ma looks more linear, but I'm inexperienced with tubes. Why did you pic .......
497: Tube DIY Asylum, Re: Newbie Alert: Parts Purchase Etiquette and Opinions (0.00)
Posted by MikeT on 2002-04-09, 21:06:07 (12.238.172.151)
To hell with them. You are the customer and you pay their salary. I don't give a damn who they are. Spend your money with someone who appreciates the business and respects you as a customer. There are .......
498: Bottlehead Forum, Opinions on Unity Gain Design (0.00)
Posted by MikeT on 2002-04-09, 13:28:42 (63.120.210.34)
I don't know if this is appropriate for this forum; if it's not please let me know. I bought an Allied 270-0-270 power tranny, some 450V Panasonic caps, two 10H chokes, and a 6BY5. I'm thinking about .......
499: Tube DIY Asylum, Re: Tube CAD Software Support (0.00)
Posted by MikeT on 2002-04-07, 05:55:42 (12.238.172.151)
Ed, there could be more to it than that in the case of D. You have to pick an operating point for the CCS. Naturally you can figure out all the voltages, do a load line, and make an assumption on what .......
500: Tube DIY Asylum, Re: Tube CAD Software Support (0.00)
Posted by MikeT on 2002-04-06, 08:17:25 (12.238.172.151)
In variations C and D of the Cathode Follower, there are calculated parts values that are never displayed in the version I have. I'm running version 1.1.3. .......
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