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1: MagneQuest/Peerless Forum, RE: Going though Mike's stuff anyone know what a BH5 & 6 are? (0.00)
Posted by Caucasian Blackplate on 2023-09-11, 15:54:19 (24.22.215.128)
Can you PM me? I would possibly buy all the BH units. .......
2: Tube DIY Asylum, I have no idea (0.00)
Posted by Caucasian Blackplate on 2019-07-28, 14:42:45 (67.170.65.56)
This place and the SET forum have turned into Dennis Fraker's free manufacturer's forum. There are AA rules that prevent this, but the moderation here is so incredibly weak here that it will probably .......
3: Amp/Preamp Asylum, RE: Motor Drive (0.00)
Posted by Caucasian Blackplate on 2019-07-21, 13:15:07 (67.170.65.56)
Is this a 120V motor or does it have a wall transformer that it uses to step the voltage down? For a 120V motor, you could use an oscillator, amplifier, and step-up transformer. For a lower voltage m .......
4: Tubes Asylum, RE: The problem with Loctals (0.00)
Posted by Caucasian Blackplate on 2019-07-21, 10:15:28 (67.170.65.56)
These are totally fine. Sometimes it is helpful to bend the center spring retainers back a little bit so the tube isn't gripped to tightly though. .......
5: Tube DIY Asylum, RE: mystery transformer (0.00)
Posted by Caucasian Blackplate on 2019-07-21, 10:13:56 (67.170.65.56)
Such a circuit would not have a power transformer, do you have one specifically you are thinking of? .......
6: Tube DIY Asylum, RE: mystery transformer (0.00)
Posted by Caucasian Blackplate on 2019-07-21, 09:57:46 (67.170.65.56)
"S" is start and "F" is finish. If you put 120V into this transformer and you don't get 870V out, then the transformer is damaged and should be thrown away. The DC rating on the secondary is a little .......
7: Speaker Asylum, RE: I Really Need Your Help (0.00)
Posted by Caucasian Blackplate on 2019-07-19, 21:34:27 (67.170.65.56)
The first thing you need to do is to go to the back of your receiver and switch the speaker cables between left and right channels. If the speaker that's not working switches sides, then your speakers .......
8: SET Asylum, RE: Is anything better than S.E.X. ? (0.00)
Posted by Caucasian Blackplate on 2019-07-17, 19:06:32 (67.170.65.56)
Some time ago I had a triamped system with RAAL ribbon tweeters. I used a SEX amp in this setup for a while before I built up my stash of directly heated monoblocks. With the parallel feed topology, .......
9: Tube DIY Asylum, RE: ping Tre or Caucasian Black (0.00)
Posted by Caucasian Blackplate on 2019-07-15, 09:17:22 (67.170.65.56)
What cathode voltages do you see on each triode of the 12AX7s in the linestage? The PAS3 would have ~70dB of gain without the tone controls in there, so you want them to pull the signal down!!! ::: T .......
10: Tube DIY Asylum, RE: ping Tre or Caucasian Black (0.00)
Posted by Caucasian Blackplate on 2019-07-15, 08:31:51 (67.170.65.56)
What plate voltages do you see on the output triodes of the 12AX7? I suspect if you poke around in there enough, you may find some components that are old and need to be replaced, or possibly that the .......
11: Speaker Asylum, RE: You wrote (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 17:18:15 (67.170.65.56)
Yes, sorry, when the L-pads are all the way up, the parallel inductor actually does something. When the L-pad gets turned down, not so much. This is perhaps intentional by JBL to keep the power handli .......
12: Speaker Asylum, RE: Defend JBL with phase and off-axis response under consideration (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 17:13:53 (67.170.65.56)
In your first post, you wrote: "An active studio monitor speaker may have a level control for "high," but it is a tone control before crossover circuit stage." A lot of studio monitors have a treble b .......
13: Amp/Preamp Asylum, RE: Gain and power make funny problems (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 17:04:27 (67.170.65.56)
The manual says 300W at idle. That's certainly something, but not all that crazy. It may be that these are class H. .......
14: Speaker Asylum, Kind of, but not really. (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 16:31:37 (67.170.65.56)
A pair of resistors can be used to pad down the signal going to a driver, but a variable L-pad is more complex. .......
15: Speaker Asylum, RE: continuous transition from 2nd order to 3rd order? (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 16:24:51 (67.170.65.56)
And why would you believe that the L-pad makes the high pass filter steeper? .......
16: Speaker Asylum, RE: WTF (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 14:50:06 (172.58.45.35)
I'm not sure what this has to do with anything else in this thread... .......
17: Speaker Asylum, RE: Outdated due to the pot? (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 14:38:25 (67.170.65.56)
I would not call an L-pad a pot. They are considerably more complicated than a potentiometer. My comment on them being outdated has more to do with the presence of two L-pads per speaker and the overa .......
18: Amp/Preamp Asylum, RE: Gain and power make funny problems (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 12:44:10 (67.170.65.56)
That amp is 240V only. The idle power consumption isn't all that bad. .......
19: General Asylum, RE: Good article w/pics plus spectrum analysis here: (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 11:35:13 (67.170.65.56)
So it makes things worse! .......
20: Speaker Asylum, WTF (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 09:16:11 (67.170.65.56)
I'm as confused as Story is now, both by the title of your last post and by what you are trying to tell us... The only thing "unique" about this crossover that you've posted is how out of date it look .......
21: Speaker Asylum, RE: High adjustment is not tweeter level control (0.00)
Posted by Caucasian Blackplate on 2019-07-14, 09:12:41 (67.170.65.56)
I see one pot in there, and it's a level pot at the input. The high frequency level adjustment has three positions; it is definitely not a pot! .......
22: Amp/Preamp Asylum, RE: Gain and power make funny problems (0.00)
Posted by Caucasian Blackplate on 2019-07-13, 14:16:19 (67.170.65.56)
You can work backwards by calculating the output voltage into 8 Ohms at full power, then take 26dB off of that and you have your input sensitivity for full power. .......
23: General Asylum, RE: PSAudio Noise Harvester AC Cleaner (0.00)
Posted by Caucasian Blackplate on 2019-07-13, 13:24:35 (67.170.65.56)
I am very, very tempted to buy one and put it on a pure 120V/60Hz sine wave to see if the light still illuminates... .......
24: Amp/Preamp Asylum, Gain and power make funny problems (0.00)
Posted by Caucasian Blackplate on 2019-07-12, 20:45:27 (67.170.65.56)
2100W into 8 ohms is about 130V AC. The amp has 26db of gain, so to actually get that kind of power out of the amp, your preamp will need to be capable of 6.5V RMS of output. I'm actually completely O .......
25: SET Asylum, RE: Dumb question (0.00)
Posted by Caucasian Blackplate on 2019-07-12, 09:01:04 (67.170.65.56)
This, IMO, depends a whole lot on what you use as the series element between the amp and the power supply. If you have a high impedance constant current source, then the output stage signal current is .......
26: Vintage Asylum, RE: re-grilling (0.00)
Posted by Caucasian Blackplate on 2019-07-11, 10:19:22 (67.170.65.56)
What happens if you need to staple the fabric onto the back surface? .......
27: Amp/Preamp Asylum, RE: D Amps (Chi Fi) are V poor (0.00)
Posted by Caucasian Blackplate on 2019-07-10, 11:33:18 (67.170.65.56)
I think it depends a fair bit on which chips you're buying. There are plenty of class D integrated circuits made to be built into TVs, laptops, etc. that are probably not a wise choice for a hifi amp. .......
28: Tube DIY Asylum, RE: Jolida JD1000A schematic? (0.00)
Posted by Caucasian Blackplate on 2019-07-10, 11:26:26 (67.170.65.56)
A reasonably well experience tube tech shouldn't need a schematic to diagnose an issue with such an amp. Find a different tech! .......
29: Amp/Preamp Asylum, RE: Taming the farting cow... (0.00)
Posted by Caucasian Blackplate on 2019-07-10, 09:52:31 (67.170.65.56)
You are summing up many of my thoughts pretty nicely. If that Manley amp needs repair in 20 years, the parts will be around. Transformers can be rewound, new caps can be purchased, and tube factories .......
30: Amp/Preamp Asylum, RE: The GND will mandate Class D amps . . . (0.00)
Posted by Caucasian Blackplate on 2019-07-09, 14:13:00 (67.170.65.56)
Nah, I sincerely doubt that. What is the idle power draw of a 3000W class D amp vs. a 10W class A tube amp? .......
31: General Asylum, Snake Oil (0.00)
Posted by Caucasian Blackplate on 2019-07-09, 13:05:47 (67.170.65.56)
This device makes these two claims: - Reduces total harmonic distortion - Adds rich musical harmonics to its output signal These statements contradict each other. .......
32: Tubes Asylum, RE: Sylvania GB 5751 (0.00)
Posted by Caucasian Blackplate on 2019-07-09, 12:59:33 (67.170.65.56)
Do you believe that the tube manufacturers back in the day made the decision to gold plate the leads based on how the tubes sounded? .......
33: Amp/Preamp Asylum, RE: +1 (0.00)
Posted by Caucasian Blackplate on 2019-07-04, 14:27:38 (67.170.65.56)
Yes, the 5800 and 5802 are definitely worth the expense. .......
34: Amp/Preamp Asylum, RE: Which Adcom amplifier??? (0.00)
Posted by Caucasian Blackplate on 2019-07-04, 12:39:40 (67.170.65.56)
Either one is going to need to be gone through to ensure proper operation and to throw away the main power supply electrolytics and replace them with something that isn't 20+ years old. .......
35: OTL Asylum, RE: Indeed, but it's driving only MR and treble into the 96dB-sensitive... (0.00)
Posted by Caucasian Blackplate on 2019-07-04, 12:12:48 (172.58.43.44)
If the midrange and treble have large changes in impedance, the amps output will tend to follow those impedance changes more with fewer output tubes installed. Though this is most audible with low fre .......
36: OTL Asylum, RE: Am now using only 2 pairs of OTs per amp, and the amps still sound... (0.00)
Posted by Caucasian Blackplate on 2019-07-04, 09:44:41 (67.170.65.56)
This will drive the output impedance of the amp up substantially. .......
37: Amp/Preamp Asylum, RE: Easy, cheap (decent though) Computer speaker amp (0.00)
Posted by Caucasian Blackplate on 2019-07-03, 13:34:41 (67.170.65.56)
JLH 1969 .......
38: Speaker Asylum, RE: "I have done this exact repair before" (0.00)
Posted by Caucasian Blackplate on 2019-07-01, 19:21:32 (67.170.65.56)
I haven't done that to an LS-50, but I've reglued a fair number of spiders. .......
39: Speaker Asylum, RE: Voice Coil Former to Spider Glue Recommendation (0.00)
Posted by Caucasian Blackplate on 2019-06-29, 19:37:19 (67.170.65.56)
I have done this exact repair before, and I used plain Jane super glue to get it done. Use just a drop or two, and let it run along the bottom edge of that old bead of glue, then reach under the spide .......
40: General Asylum, RE: How much is this set really worth? (0.00)
Posted by Caucasian Blackplate on 2019-06-28, 07:45:22 (67.170.65.56)
I would estimate that the pair of amps should top out under $5k, and a bit less for the preamp. .......
41: Tubes Asylum, +1 (0.00)
Posted by Caucasian Blackplate on 2019-06-27, 10:58:56 (67.170.65.56)
We have used lots of those and they have been incredibly reliable. We have also had lots of customers balk at the fork pin interface and use other sockets, and many of them have not been so lucky. ::: .......
42: Tube DIY Asylum, RE: g2 regulation with zeners : schematic (0.00)
Posted by Caucasian Blackplate on 2019-06-27, 10:54:46 (67.170.65.56)
You can also use tube zeners. They look really cool! .......
43: Tube DIY Asylum, RE: g2 regulation with zeners : schematic (0.00)
Posted by Caucasian Blackplate on 2019-06-27, 09:16:56 (67.170.65.56)
Be careful with the dissipation on those 1W zeners. I wouldn't let them run with more than 1/3 of a W of constant dissipation. .......
44: Tube DIY Asylum, RE: 21st century maida regulator (0.00)
Posted by Caucasian Blackplate on 2019-06-27, 09:14:35 (67.170.65.56)
For prototyping, why not pick up an adjustable bench supply? My issue with using something like that Maida regulator for what you want to do is that you are going to need to keep a very, very close ey .......
45: Tube DIY Asylum, RE: 1958 Hafler Article (0.00)
Posted by Caucasian Blackplate on 2019-06-27, 09:10:47 (67.170.65.56)
That seems very convenient that the resistor value they chose happens to both be the best for IM performance and creates the ideal voltage reference that equals a fresh D-cell battery. Next time I hav .......
46: Amp/Preamp Asylum, RE: Depends (0.00)
Posted by Caucasian Blackplate on 2019-06-24, 07:56:41 (67.170.65.56)
I mentioned impedance in general (source and load) and cable capacitance. Cable impedance is negligible unless they get very long. The passive question comes up a lot and these issues tend to get freq .......
47: Amp/Preamp Asylum, RE: Depends (0.00)
Posted by Caucasian Blackplate on 2019-06-23, 18:40:01 (67.170.65.56)
You are ignoring impedance and cable capacitance issues. A preamp is not just a voltage amplifier and a pot. .......
48: Tubes Asylum, RE: Help to find 100 ohm resistor for Atlas Magnum please. (0.00)
Posted by Caucasian Blackplate on 2019-06-23, 17:53:35 (67.170.65.56)
The last Cronus Magnum I worked on had a fuse for each tube. 100 ohms of resistance added to the Rp of each output tube isn't huge. .......
49: Tubes Asylum, RE: Help to find 100 ohm resistor for Atlas Magnum please. (0.00)
Posted by Caucasian Blackplate on 2019-06-23, 13:02:18 (67.170.65.56)
My assumption is that these are intended to blow if an output tube shorts. 100 ohms between the output transformer primary and the plate is pretty meaningless, but 100 ohms between the cathode and gro .......
50: Tubes Asylum, RE: Help to find 100 ohm resistor for Atlas Magnum please. (0.00)
Posted by Caucasian Blackplate on 2019-06-23, 09:50:34 (67.170.65.56)
I would be willing to bet that if you e-mailed Rogue they would just mail you one. .......
51: Amp/Preamp Asylum, There are good reasons (0.00)
Posted by Caucasian Blackplate on 2019-06-23, 09:41:18 (67.170.65.56)
Let's say that you have a tube DAC that you love with a 1500 ohm output impedance and you are biamping your speakers with a pair of solid state amps with 10K input impedance each. Your DAC sits next .......
52: Tube DIY Asylum, RE: Curse of being "handy" (0.00)
Posted by Caucasian Blackplate on 2019-06-21, 19:49:05 (67.170.65.56)
I have learned to just be quiet about that stuff around certain people. My best friend from HS doesn't understand why I don't see him anymore. It hasn't occurred to him that the $5 hat he gave me for .......
53: Speaker Asylum, RE: Aurum Cantus? (0.00)
Posted by Caucasian Blackplate on 2019-06-21, 09:19:51 (67.170.65.56)
Maybe one day they will sell the AC130/DC50SC to the public! .......
54: Speaker Asylum, Aurum Cantus? (0.00)
Posted by Caucasian Blackplate on 2019-06-20, 20:17:59 (67.170.65.56)
Their lineup is quite large. .......
55: Amp/Preamp Asylum, RE: Stepped attenuator ? (0.00)
Posted by Caucasian Blackplate on 2019-06-20, 20:02:09 (67.170.65.56)
This is all well and good until you put a DAC with a tube output stage with higher output impedance. The Bryston isn't all that bad with its 50K input impedance, but there are plenty of solid state .......
56: Amp/Preamp Asylum, RE: Recording from variable output (0.00)
Posted by Caucasian Blackplate on 2019-06-19, 08:02:42 (67.170.65.56)
What is the output impedance of the Ayon and what's the input impedance of the Jil? How long are the cables you're using between them, and how much capacitance per foot/meter do they have? ::: TOPIC:: .......
57: Tube DIY Asylum, RE: DHT versus IHT (0.00)
Posted by Caucasian Blackplate on 2019-06-19, 08:00:04 (67.170.65.56)
The valve issues can be downloaded for free. The articles cover both topics. .......
58: Tube DIY Asylum, RE: DHT versus IHT (0.00)
Posted by Caucasian Blackplate on 2019-06-18, 11:56:02 (67.170.65.56)
My recommended reading for this topic would be: Valve December 1997 - "Why does zero feedback single ended sound so good?" Valve 1998 volume 3/4/5 articles on triode loading, with a heavy emphasis on .......
59: Tube DIY Asylum, RE: CB (0.00)
Posted by Caucasian Blackplate on 2019-06-18, 07:00:50 (67.170.65.56)
Yes, so if you put grid chokes anywhere in that amp other than right at the input, it will be in the feedback loop. .......
60: SET Asylum, RE: 805 Class A2 Amp (0.00)
Posted by Caucasian Blackplate on 2019-06-17, 20:01:41 (67.170.65.56)
The 805 isn't so bad if you use a 12V transformer and a modest choke input filter. If you have a PT with two 6V/5+A windings, then things are pretty easy. The 811 is a little worse though! ::: TOPIC:: .......
61: Tube DIY Asylum, RE: CB (0.00)
Posted by Caucasian Blackplate on 2019-06-17, 18:09:21 (67.170.65.56)
Yes, and that goes back to the cathode of the first driver stage? .......
62: Tube DIY Asylum, RE: what it is??? (0.00)
Posted by Caucasian Blackplate on 2019-06-17, 15:14:12 (67.170.65.56)
Look for a single ended EL84 schematic. .......
63: Tube DIY Asylum, RE: Grid choke on pentode or triode? (0.00)
Posted by Caucasian Blackplate on 2019-06-17, 13:24:22 (172.56.42.73)
I wouldn't use these inside a feedback loop. I also wouldn't use them in a driver stage, as a properly designed driver stage won't benefit from their properties. .......
64: Tube DIY Asylum, RE: what it is??? (0.00)
Posted by Caucasian Blackplate on 2019-06-17, 13:22:31 (172.56.42.73)
Are you a headphone listener or a speaker listener? .......
65: Tube DIY Asylum, RE: what it is??? (0.00)
Posted by Caucasian Blackplate on 2019-06-17, 09:13:40 (67.170.65.56)
If you had a second one, you could make a small stereo tube amp. .......
66: Amp/Preamp Asylum, RE: Aging amp (0.00)
Posted by Caucasian Blackplate on 2019-06-16, 18:07:17 (67.170.65.56)
Old caps with high leakage aren't as easy to charge as fresh ones. .......
67: OTL Asylum, RE: Help with Autotransformers (0.00)
Posted by Caucasian Blackplate on 2019-06-16, 12:49:49 (67.170.65.56)
Yes, you should have lower volume, were you expecting different results? If you use the autotransformer to step the speaker load down, then you are defeating the entire purpose of doing this in the fi .......
68: Tube DIY Asylum, RE: Terminating DC Link Capacitors. (0.00)
Posted by Caucasian Blackplate on 2019-06-16, 12:47:19 (67.170.65.56)
Goop them to the chassis with RTV (available at your local autoparts store). Definitely do not use normal silicone though! .......
69: Amp/Preamp Asylum, RE: Aging amp (0.00)
Posted by Caucasian Blackplate on 2019-06-16, 11:40:13 (67.170.65.56)
They well may be leaking electrically. I have had perfect looking caps destroy a power transformer. You can't tell much just by looking at them. .......
70: Amp/Preamp Asylum, RE: Aging amp (0.00)
Posted by Caucasian Blackplate on 2019-06-16, 11:24:29 (67.170.65.56)
How did you thoroughly inspect the capacitors? .......
71: Amp/Preamp Asylum, Aging amp (0.00)
Posted by Caucasian Blackplate on 2019-06-16, 10:14:32 (67.170.65.56)
The 5503 is from the mid 90s, right? It is completely possible that marginal power supply capacitors are what's at fault here. For the age of the unit, replacing them would be a good idea regardless. .......
72: Tube DIY Asylum, RE: It's hard to beat a 2A3, push pull or SE..... (0.00)
Posted by Caucasian Blackplate on 2019-06-16, 09:57:24 (67.170.65.56)
There would be a big difference on the bottom end. You would hear it. Depending on which configurations you're using, there might also be a significant difference on the top end. .......
73: Tube DIY Asylum, RE: It's hard to beat a 2A3, push pull or SE..... (0.00)
Posted by Caucasian Blackplate on 2019-06-16, 08:51:59 (67.170.65.56)
If you are still using the Hammond 125SE, it might be time to commit to a slightly nicer pair of OTs. .......
74: SET Asylum, RE: WE91 type amp OPT choices? (0.00)
Posted by Caucasian Blackplate on 2019-06-16, 08:46:46 (67.170.65.56)
The TFA-204 will be a little light on the bottom end. The 91A circuit will be a little light on the top end. The TFA-2004 and a proper plate choke would be a much better choice. .......
75: Tubes Asylum, RE: Help with tube valuation (0.00)
Posted by Caucasian Blackplate on 2019-06-15, 13:06:07 (67.170.65.56)
That's a $10-20 quad of tubes untested. If you can get them tested, especially on a transconductance tester, you could motivate buyers to pay more. .......
76: Speaker Asylum, RE: Foam port plugs (0.00)
Posted by Caucasian Blackplate on 2019-06-15, 09:02:19 (67.170.65.56)
McMaster Carr has silicone, cork, and rubber tapered plugs. .......
77: Tube DIY Asylum, RE: So, prolly shortcuts on both. (0.00)
Posted by Caucasian Blackplate on 2019-06-14, 21:34:30 (67.170.65.56)
It's really hard to say on the engineering part. The designer could have specified 5W through hole Zener diodes, then the manufacturer put in the surface mount parts that failed. Rarely would the engi .......
78: SET Asylum, RE: WE91 type amp OPT choices? (0.00)
Posted by Caucasian Blackplate on 2019-06-14, 20:07:40 (67.170.65.56)
The LL1664/100mA would be a decent budget option. The LL1623/90mA is well suited to your project for about $500 the pair. If you buy covers for them so you can mount them on top of your chassis, that .......
79: SET Asylum, RE: WE91 type amp OPT choices? (0.00)
Posted by Caucasian Blackplate on 2019-06-14, 18:13:02 (67.170.65.56)
The proper replacement would be the Magnequest TFA-204. If you want performance like the 91A, then you aren't going to get particularly wonderful bass or very open treble. If you want a significant .......
80: Tube DIY Asylum, RE: Ways to measure grid choke? (0.00)
Posted by Caucasian Blackplate on 2019-06-14, 18:00:45 (67.170.65.56)
Get a signal generator with a low output impedance. Put a 1M pot in series with the grid choke and set it up as a variable resistor. Run your generator with 10V or so at 60Hz, then set the pot so that .......
81: Tube DIY Asylum, RE: Interesting. (0.00)
Posted by Caucasian Blackplate on 2019-06-14, 17:58:55 (67.170.65.56)
The caps that I pulled out were no name parts and considerably smaller than the Lelon caps that I put in. I replaced the 100uF/450V snap in cap too just for good measure. In a schematic that I found, .......
82: Tube DIY Asylum, Monoprice Guitar Amp Repair (0.00)
Posted by Caucasian Blackplate on 2019-06-14, 16:51:50 (67.170.65.56)
For those out there with the 15W Monoprice guitar amp, a customer of mine brought one over today for repairs. The symptom was a very sudden onset of almost no output whatsoever. I went through .......
83: Tube DIY Asylum, RE: Antek AS-2T350 - B+ voltage expected? (0.00)
Posted by Caucasian Blackplate on 2019-06-13, 13:19:30 (67.170.65.56)
Assuming you're going to use solid state rectification, you can expect roughly 450V of B+ with the windings in series using a full wave rectifier with the center tap grounded. In a quick PSUD simulati .......
84: High Efficiency Speaker Asylum, RE: A SHOCKER -really ! (0.00)
Posted by Caucasian Blackplate on 2019-06-13, 08:48:34 (67.170.65.56)
Frequency response is only one of many graphs. .......
85: Speaker Asylum, RE: Ha! You'd be lucky to find it at that price! (0.00)
Posted by Caucasian Blackplate on 2019-06-11, 14:42:49 (67.170.65.56)
Dan is busy preparing for his second trip to the salt flats in Utah to set another motorcycle land speed record. The headphone community in the bay area is thriving. That isn't so difficult to fit int .......
86: Speaker Asylum, RE: Audio in the SF Bay Area (0.00)
Posted by Caucasian Blackplate on 2019-06-11, 14:20:40 (67.170.65.56)
After spending $1 million on an 1,100 square foot house in Palo Alto, is there still budget/space for a hifi system? .......
87: Tube DIY Asylum, You Hit the Nail on the Head!!! (0.00)
Posted by Caucasian Blackplate on 2019-06-11, 13:56:47 (67.170.65.56)
I can't ever remember a time where ignorance has had more value than today! .......
88: Tube DIY Asylum, RE: I disagree, it's not just his manner, his circuit ideas don't stack up, either. (0.00)
Posted by Caucasian Blackplate on 2019-06-11, 13:46:51 (67.170.65.56)
A long, long time go I had a #45 amp that used A470s as output transformers. I rather liked it at the time, but I didn't have much to compare it to. .......
89: Amp/Preamp Asylum, RE: Want A Flame Linear ? (0.00)
Posted by Caucasian Blackplate on 2019-06-10, 11:19:04 (172.58.43.141)
The bigger the blob, the messier the slob. .......
90: Tube DIY Asylum, RE: Low Mu's KT-88 update (0.00)
Posted by Caucasian Blackplate on 2019-06-10, 09:31:46 (67.170.65.56)
I'm a doer, I just don't post anything about my projects where Jeff's disciples dwell. I'm glad the Klipsch forum gave him the boot and a little sad it took AA ten years to do the same. .......
91: Tubes Asylum, RE: Understanding Tube Adapters (0.00)
Posted by Caucasian Blackplate on 2019-06-10, 08:54:13 (67.170.65.56)
If you want to use a 6SN7 in a position where a 12AX7 normally resides, you will need a heck of a lot more than an adapter. .......
92: Tubes Asylum, RE: Right, so is there something that would .. . (0.00)
Posted by Caucasian Blackplate on 2019-06-09, 13:36:10 (172.58.46.251)
Yes, turn your amp on 30 minutes before you want to listen. If necessary you can get outlets with timers or that you can control from your phone. .......
93: Tubes Asylum, RE: I have heard amp that sound . . (0.00)
Posted by Caucasian Blackplate on 2019-06-09, 09:05:33 (67.170.65.56)
Yes, tube gear does need a short warm up to sound its best. With just the tube heaters running, none of the components you listed will be settled from being in standby. .......
94: Amp/Preamp Asylum, RE: Want A Flame Linear ? (0.00)
Posted by Caucasian Blackplate on 2019-06-09, 09:03:31 (67.170.65.56)
That sounds pretty typical for what I see. I'm working on a Fisher 300 power amp right now that has been "tweaked". It is full of Russian PIO capacitors that have a conductive metal case. Some of thos .......
95: Tubes Asylum, RE: Juke boxes had a standby mode that kept the heater at a low voltage. . (0.00)
Posted by Caucasian Blackplate on 2019-06-08, 15:07:15 (67.170.65.56)
I have never met a tube amp owner who was bothered by waiting 30 seconds for the amp to warm up. .......
96: Tube DIY Asylum, RE: Started the pair of 6GM5/WE133A hybrid amps (0.00)
Posted by Caucasian Blackplate on 2019-06-08, 09:06:12 (67.170.65.56)
I have a slightly different version of that bench supply, you don't want to pay for shipping! .......
97: Tube DIY Asylum, RE: Basic tube testing - questions!! (0.00)
Posted by Caucasian Blackplate on 2019-06-03, 13:50:59 (67.170.65.56)
3K/3mA will give -9V of bias for an indirectly heated tube and an average bias of -9V for a directly heated tube provided you connect it to a virtual center on the filament. Your drawing shows that it .......
98: Tubes Asylum, RE: Pic Attached (0.00)
Posted by Caucasian Blackplate on 2019-06-03, 08:51:53 (67.170.65.56)
Find a long machine screw that has a head that will fit into the hollow section of that octal key, then hit the auto parts store and get the quick epoxy that has the long mixing nozzle. I've popped up .......
99: Tube DIY Asylum, RE: Is "non-inductive" of any real importance for dummy loads? (0.00)
Posted by Caucasian Blackplate on 2019-06-02, 13:44:33 (67.170.65.56)
I would not expect the inductance of a wirewound resistor to be anything near the inductance of the voice coil of a tweeter. .......
100: Speaker Asylum, RE: Is there a better monitor than the ATM SCM19? (0.00)
Posted by Caucasian Blackplate on 2019-06-02, 10:40:43 (67.170.65.56)
I would certainly give the little Magico monitors a listen, but I could certainly live with a pair of SCM19s, regardless of system budget. .......
101: Tube DIY Asylum, RE: Testing with/without Load??? (0.00)
Posted by Caucasian Blackplate on 2019-06-01, 16:48:55 (67.170.65.56)
In a preamp, this isn't an issue. If you have a tube power amp with pentode wired finals, the gain of that stage gets very high with no load on the output transformer secondary, and this is a big conc .......
102: Amp/Preamp Asylum, RE: More costs (0.00)
Posted by Caucasian Blackplate on 2019-05-31, 10:12:00 (172.58.43.78)
Sure, they'll run on a 15A circuit. Both would actually run on a single 15A circuit. If you push them well past their idle operating conditions, then you'll run into problems. Still, there's probably .......
103: Amp/Preamp Asylum, RE: More costs (0.00)
Posted by Caucasian Blackplate on 2019-05-31, 10:10:10 (172.58.43.78)
Thankfully circuit breakers don't trip that quickly! The 5kW per amp seemed adequate for most applications, but yes, you could also increase your feed from the street (I think it's 400A max where I li .......
104: Amp/Preamp Asylum, More costs (0.00)
Posted by Caucasian Blackplate on 2019-05-31, 09:12:51 (67.170.65.56)
You'd also need to wire in some 240V outlets. A dedicated 240V/20A outlet for each amp would be sensible. .......
105: Tube DIY Asylum, RE: VT200 bias all over the place (0.00)
Posted by Caucasian Blackplate on 2019-05-31, 09:03:14 (67.170.65.56)
You need to stop changing parts and actually take some measurements to see what's going on. If you change the parts enough, you will do damage to the PC board and brick the amp. .......
106: Tube DIY Asylum, RE: VT200 bias all over the place (0.00)
Posted by Caucasian Blackplate on 2019-05-31, 06:44:45 (67.170.65.56)
Well, you have an amp that's possible from 1998. All the caps in the amp are either 20 years old, or approaching 20 years old. If you had a bad capacitors in the bias supply, all the output tubes woul .......
107: Speaker Asylum, RE: anyone measured excessive top end in JBL 4319? (0.00)
Posted by Caucasian Blackplate on 2019-05-30, 10:08:50 (67.170.65.56)
If you look at the THD plot, there's definitely something going on at 18kHz! .......
108: Tube DIY Asylum, RE: 2a3 with tango output transformer (0.00)
Posted by Caucasian Blackplate on 2019-05-28, 08:38:37 (67.170.65.56)
Parallel 2A3s on the U-808 could be pretty nice, but what does that get you over using a single 300B? Otherwise I quite agree with Chip's assessment. .......
109: General Asylum, RE: Fluctuation in voltage on a LPS (0.00)
Posted by Caucasian Blackplate on 2019-05-27, 22:09:13 (67.170.65.56)
Is it listed as a regulated linear power supply? If it's not regulated, then this variance isn't abnormal. If it read 4.8-ish volts when you first plugged it in, and you've left it plugged in and the .......
110: Tubes Asylum, RE: It's the tubes. (0.00)
Posted by Caucasian Blackplate on 2019-05-26, 08:47:28 (67.170.65.56)
Woah, hold on a second, on what basis would you say that there's a defect in the tubes? I have never seen any specifications for startup or cooldown noise. .......
111: Amp/Preamp Asylum, RE: How come my amp is still working? (0.00)
Posted by Caucasian Blackplate on 2019-05-25, 10:02:04 (67.170.65.56)
You can't just look at them and know what's going on electrically. I've had caps that looked absolutely perfect destroy a power transformer because they were old and worn out. If your DNA-1 hasn't see .......
112: SET Asylum, RE: Speaker cables for 300B synergy? (0.00)
Posted by Caucasian Blackplate on 2019-05-25, 09:17:39 (67.170.65.56)
If you have lean tonal balance, I would be looking more at your output iron, 300B operating point, and driver design. It would also help to review the impedance curve of your speakers as well. ::: TO .......
113: Tube DIY Asylum, RE: 27-71a design (0.00)
Posted by Caucasian Blackplate on 2019-05-24, 08:59:49 (67.170.65.56)
An 18K resistor would work in place of the choke and the dropping resistor that is unlabeled in your drawing. The choke you are currently using is undoubtedly a power supply choke and will not work p .......
114: Tube DIY Asylum, RE: Dynaco SCA-35 Revisited (0.00)
Posted by Caucasian Blackplate on 2019-05-22, 12:06:27 (67.170.65.56)
He is absolutely correct. For C17, a polystyrene cap is often suggested as a superior replacement to the OG ceramic caps. .......
115: Tube DIY Asylum, RE: I am not sure about my Fisher 800c bias circuit results (0.00)
Posted by Caucasian Blackplate on 2019-05-21, 16:12:02 (67.170.65.56)
Just pull one of the red HV wires from its terminal so there's no B+ to worry about, then get a little more adventurous with the variac! .......
116: Amp/Preamp Asylum, RE: Volume control maximum? (0.00)
Posted by Caucasian Blackplate on 2019-05-21, 08:13:03 (67.170.65.56)
You would have to measure the output level of each source, then determine at which point on the volume control your amp would clip for each source, then leave a little sticker at each of those positio .......
117: Tube DIY Asylum, RE: No not yet (0.00)
Posted by Caucasian Blackplate on 2019-05-20, 08:43:11 (67.170.65.56)
They are a real pain in the butt to redo because they don't visually look like they are supposed to! I have a 400 here that I'm pretty sure I redid the bias supply on, if you want I can take some clos .......
118: Tube DIY Asylum, RE: Electraprint DRD 300B (0.00)
Posted by Caucasian Blackplate on 2019-05-20, 08:41:40 (67.170.65.56)
Why go with 5K over 3K or 3.5K? There are very, very few 5K output transformers that do a good job of supporting deep bass, but the job gets much easier when you move down toward 3K. -PB .......
119: Tubes Asylum, RE: 6L6 family tubes in Rogue M180 (0.00)
Posted by Caucasian Blackplate on 2019-05-16, 19:32:39 (67.170.65.56)
The design requirements to get that kind of power will exclude the 6L6 family based on transformer primary impedance alone without even considering the voltages and currents in question. The only exce .......
120: Tubes Asylum, RE: 6L6 family tubes in Rogue M180 (0.00)
Posted by Caucasian Blackplate on 2019-05-15, 20:06:22 (67.170.65.56)
Firecrackers, not so much. You're likely just looking at sub-par performance out of that amp with 6L6 family tubes used. .......
121: Tube DIY Asylum, RE: DRD 300B power supply (0.00)
Posted by Caucasian Blackplate on 2019-05-15, 15:42:32 (67.170.65.56)
If you have a phobia of resistors, then sure, you could build that design. .......
122: Amp/Preamp Asylum, RE: High/Low Bias - question (0.00)
Posted by Caucasian Blackplate on 2019-05-13, 19:38:57 (67.170.65.56)
You don't think that the proximity of the "bias" switch to the power switch suggests that perhaps the primary of the power transformer has a lower voltage tap that just slightly drops the +/- rails on .......
123: Tube DIY Asylum, RE: DRD 300B power supply (0.00)
Posted by Caucasian Blackplate on 2019-05-13, 19:24:33 (67.170.65.56)
The regulator is likely to knock the power supply ripple down considerably compared to the CLC. If you're scratch building this and you have a 6.3V winding to heat your 300Bs, you can use a full wave .......
124: Amp/Preamp Asylum, RE: High/Low Bias - question (0.00)
Posted by Caucasian Blackplate on 2019-05-12, 09:28:43 (67.170.65.56)
The manufacturer could probably tell you that. To switch from 300W class A to 200W class A and reduce the heat put off by the amp, one option would be to switch to a lower voltage set of taps on the p .......
125: Tubes Asylum, RE: Remove capacitors in the circuit?? (0.00)
Posted by Caucasian Blackplate on 2019-05-12, 08:32:45 (67.170.65.56)
Along with what the others have said, these are absolutely not in the signal path. .......
126: Amp/Preamp Asylum, RE: High/Low Bias (0.00)
Posted by Caucasian Blackplate on 2019-05-12, 08:31:01 (67.170.65.56)
The difference between 200W and 300W is a little less than 2dB, so it's not enormous. You didn't say whether there is any class B power available in the low bias setting, but your observations may ind .......
127: Tube DIY Asylum, RE: Negative bias voltage supply for Fisher 800C (0.00)
Posted by Caucasian Blackplate on 2019-05-10, 10:15:40 (67.170.65.56)
I would recommend keeping it stock. What I have done in the past is to pack four electrolytic caps into the spring clip that holds the cardboard cap, then use a zip tie on top of that clamp to keep so .......
128: Computer Audio Asylum, RE: Plug in jack-rack limiter help needed (0.00)
Posted by Caucasian Blackplate on 2019-05-10, 09:18:56 (67.170.65.56)
How painful would it be to justify using a different amplifier? What is the amp you're using? Is there a 4 ohm version of your subwoofer? Can you add a second identical 8 ohm woofer? (you know you wan .......
129: Speaker Asylum, RE: Speaker repair (0.00)
Posted by Caucasian Blackplate on 2019-05-10, 09:11:56 (67.170.65.56)
I've sent a fair number of people his way. We have the first name and we live a short drive from each other, so often times people ask if I'm the speaker repair guy. Everybody I know who has had work .......
130: Amp/Preamp Asylum, RE: Timed out .. (0.00)
Posted by Caucasian Blackplate on 2019-05-09, 09:50:28 (67.170.65.56)
How robust of a power supply do you need for a preamp? Undoubtedly the preamp itself is loaded with voltage regulators. .......
131: Tube DIY Asylum, RE: "how would I calculate the difference needed?" (0.00)
Posted by Caucasian Blackplate on 2019-05-09, 09:26:50 (67.170.65.56)
Yes, the cell phone is to be used as a signal generator. A $40 Android tablet would also do the job. .......
132: Tube DIY Asylum, RE: "how would I calculate the difference needed?" (0.00)
Posted by Caucasian Blackplate on 2019-05-09, 09:11:57 (67.170.65.56)
If you have a cell phone and a DVM that can read AC volts, you can take the measurements Chip is suggesting. The difficulty with the circuit as proposed is that it performs poorly if you push into cla .......
133: Amp/Preamp Asylum, RE: Aragon Ingot Repair (0.00)
Posted by Caucasian Blackplate on 2019-05-07, 21:48:20 (67.170.65.56)
Hello Bob, You very likely can deviate a little with no harm done. What's nice about this supply is that it seems to be always on, so you can test it without having it plugged into your preamp. I woul .......
134: Amp/Preamp Asylum, RE: Aragon Ingot Repair (0.00)
Posted by Caucasian Blackplate on 2019-05-07, 15:51:27 (67.170.65.56)
If you have a bipolar bridge rectified power supply with a resistor on each leg feeding a regulating zener, then a dead capacitor will draw the full power supply voltage across the dropping resistor a .......
135: Amp/Preamp Asylum, RE: Aragon Ingot Repair (0.00)
Posted by Caucasian Blackplate on 2019-05-07, 12:17:55 (67.170.65.56)
This power supply looks to be always on, so that's why it failed when your preamp was off. How old is this power supply? It's totally possible that a failed capacitor has caused that resistor to pop. .......
136: Amp/Preamp Asylum, RE: Doge Audio Troubles (0.00)
Posted by Caucasian Blackplate on 2019-05-07, 07:03:15 (67.170.65.56)
This seems to be par for the course. On another forum I got peer pressured into buying an inexpensive Chinese amp to measure. Naturally it makes significantly less power than claimed, so I asked for a .......
137: SET Asylum, RE: Original SE 845 PS schematic (0.00)
Posted by Caucasian Blackplate on 2019-05-06, 08:39:57 (67.170.65.56)
If you have spare voltage coming off the bridge connected to the 10V winding, making the supply a resistor input will reduce the AC current on that winding. (Remove the 10,000uF/25V cap and play with .......
138: General Asylum, RE: Two amps and one set of speakers? (0.00)
Posted by Caucasian Blackplate on 2019-05-05, 08:46:39 (67.170.65.56)
It looks like Rod has a few SET amplifiers and these do not needed to have a load on the output. Their gain is very much finitely limited by the mu of the tubes themselves (not so much when you move t .......
139: Tube DIY Asylum, RE: High Power Push Pull Amp using Type 27 Driver Tubes (0.00)
Posted by Caucasian Blackplate on 2019-05-04, 08:43:45 (67.170.65.56)
Why not get some 1624s and go all 2.5V with directly heated finals? .......
140: Tubes Asylum, RE: Resistors for Sonic Frontiers SFL-1 (0.00)
Posted by Caucasian Blackplate on 2019-05-04, 08:21:59 (67.170.65.56)
How have you come to the conclusion that what's in there now is inductive? For at least two of the parts you've mentioned, I bet they are already non inductive parts. .......
141: Tube DIY Asylum, RE: Littelfuse series 218 slo-blo fuse (0.00)
Posted by Caucasian Blackplate on 2019-05-03, 22:12:26 (67.170.65.56)
Your neighborhood hardware store will have 5x20mm fuses. The slo-blo attribute may be a little harder to find though. Mouser will have lots of these. You could also go to www.google.com and type in " .......
142: Tube DIY Asylum, RE: High Power Push Pull Amp using Type 27 Driver Tubes (0.00)
Posted by Caucasian Blackplate on 2019-05-03, 22:09:37 (67.170.65.56)
Electrically speaking, the #27 is pretty small. Plate dissipation is only around 1W, and the cathode insulation rating is poor. If you wanted to build a cathodyne phase inverter, you would need separa .......
143: SET Asylum, RE: How to dispose of 845 amps (0.00)
Posted by Caucasian Blackplate on 2019-05-03, 07:16:55 (67.170.65.56)
List them on the Asylum Trader. One thing though, do not try to ship them under any circumstances! .......
144: General Asylum, RE: My bad - I need an online calculator..... (0.00)
Posted by Caucasian Blackplate on 2019-05-02, 12:17:44 (67.170.65.56)
You'll need more than just the calculator to know what range of values will be appropriate for your situation. .......
145: Tube DIY Asylum, +1,000,000 nt (0.00)
Posted by Caucasian Blackplate on 2019-04-30, 12:27:44 (67.170.65.56)
nt .......
146: Tube DIY Asylum, RE: SE KT88 : bold new design (0.00)
Posted by Caucasian Blackplate on 2019-04-30, 08:41:02 (67.170.65.56)
Wow, a forum that hasn't kicked him off yet? It will be interesting to see him gush all over a zero feedback pentode finals amp (they have glaring audible issues). .......
147: SET Asylum, RE: 300B overbias / underbias questions (0.00)
Posted by Caucasian Blackplate on 2019-04-28, 07:58:27 (67.170.65.56)
There's no mention of distortion in the 15W power rating. That could be peak output power. .......
148: Tube DIY Asylum, RE: Phono stage CCS modification help (0.00)
Posted by Caucasian Blackplate on 2019-04-28, 07:54:48 (67.170.65.56)
You have a cascode as the first stage and it needs a resistive load to work into. If you want to use the CCS, then you will need to put the 82K resistor from the plate of the upper tube to ground, the .......
149: SET Asylum, RE: SET w/ Feedback (0.00)
Posted by Caucasian Blackplate on 2019-04-27, 19:10:08 (67.170.65.56)
The global feedback will help in the low bass with the F913 output transformer. This could also be useful if the amp was AC heated to keep the noise floor low. As it is, the design does not use a hum .......
150: SET Asylum, RE: 300B overbias / underbias questions (0.00)
Posted by Caucasian Blackplate on 2019-04-27, 18:39:30 (67.170.65.56)
The maximum plate current for a single 300B is 100mA, so hopefully there is just one adjustment that is adjusting both tubes? Going too high can cause performance issues from the output transformers a .......
151: SET Asylum, RE: Looking for a 10v x 5.0A DC supply (0.00)
Posted by Caucasian Blackplate on 2019-04-27, 18:35:06 (67.170.65.56)
Use a 12V transformer, a beefy choke, and a few big caps in parallel. .......
152: General Asylum, RE: Anyone ever build one of these? (0.00)
Posted by Caucasian Blackplate on 2019-04-27, 18:23:05 (67.170.65.56)
I received the JBH EL34 amplifier on Friday and did some measurements later in the day. The amp made 4W at 10% THD at 1kHz (the seller claimed 8W at less than 1% THD naturally). There wasn't really an .......
153: SET Asylum, RE: Doing SET Backwards (0.00)
Posted by Caucasian Blackplate on 2019-04-26, 15:37:43 (67.170.65.56)
Lifetime for a 300B depends a whole lot on plate to cathode voltage and not being too far off the specified filament voltage rather than plate dissipation. Remember that it's the filament that wears .......
154: General Asylum, RE: What you will get... (0.00)
Posted by Caucasian Blackplate on 2019-04-25, 17:45:13 (67.170.65.56)
I have the "better" version of that amp arriving tomorrow since some folks on another forum wanted a review. I can PM you a link to it if you'd like. .......
155: SET Asylum, Distortion and Power (0.00)
Posted by Caucasian Blackplate on 2019-04-25, 09:14:12 (67.170.65.56)
From the website for the SIT-2, I see 10W at 3% distortion. Are you implying that this is a vast improvement over 7W at 5% distortion? The gap narrows if you switch to 4 ohm speakers too... You're spl .......
156: Speaker Asylum, RE: Why do these speakers sound as good as they do? (0.00)
Posted by Caucasian Blackplate on 2019-04-25, 08:12:08 (67.170.65.56)
Are you sure the drivers aren't exotic? It could be loaded with Vifa drivers, which would be a good start. The arrangement of the two woofers is pretty unique I must admit. .......
157: General Asylum, What you will get... (0.00)
Posted by Caucasian Blackplate on 2019-04-25, 08:03:58 (67.170.65.56)
I had a college student bring by a Nobsound preamp kit built with many of the same parts I see in that auction. Here's a photo of one of the capacitors out of the kit (they went in the trash after .......
158: Tube DIY Asylum, RE: J&K Audio Design: Best in class audio transformers (0.00)
Posted by Caucasian Blackplate on 2019-04-25, 07:52:40 (67.170.65.56)
Ah, so you didn't use them for output iron? .......
159: Speaker Asylum, RE: Sensitivity of Joseph Audio Pulsar? (0.00)
Posted by Caucasian Blackplate on 2019-04-24, 08:22:48 (67.170.65.56)
This was exactly my thought! .......
160: Tube DIY Asylum, RE: J&K Audio Design: Best in class audio transformers (0.00)
Posted by Caucasian Blackplate on 2019-04-24, 07:43:27 (67.170.65.56)
Are you permitted to share the price you paid? The specs for the GM70 iron look pretty promising. .......
161: Tubes Asylum, RE: Anyone know where I can find a 600k stereo volume pot (0.00)
Posted by Caucasian Blackplate on 2019-04-23, 20:09:08 (67.170.65.56)
You could probably use a 500K audio taper pot with loudness and add a 100K resistor in series with the input to bring it up to 600K. I would be impressed if you could fit a Goldpoint into an S5000! :: .......
162: General Asylum, RE: New System (0.00)
Posted by Caucasian Blackplate on 2019-04-23, 09:01:57 (67.170.65.56)
For the LRS, check your Rogue owner's manual about changing the amp to the 4 ohm taps. .......
163: Tube DIY Asylum, RE: Aluminum Power Transformer Covers (0.00)
Posted by Caucasian Blackplate on 2019-04-21, 19:19:26 (67.170.65.56)
Are you powering the 300B from the 6.3V winding? (With DC conversion?) The 374BX is rated at 201mA AC current. If you have a cap input filter and you intend to draw 105mA of DC current, then you will .......
164: Amp/Preamp Asylum, RE: Installing power tubes in a Rogue Cronos Magnum II (0.00)
Posted by Caucasian Blackplate on 2019-04-21, 08:29:53 (67.170.65.56)
It's good that you paused to ask. I repaired one of these earlier this year where the owner just jammed in the output tubes without paying any attention. He completely destroyed two of the tube socket .......
165: Amp/Preamp Asylum, RE: Installing power tubes in a Rogue Cronos Magnum II (0.00)
Posted by Caucasian Blackplate on 2019-04-21, 07:52:01 (67.170.65.56)
The octal base of each tube has a plastic center pin, and that plastic center pin has a notch on it. This will only fit in the socket one way unless you are extremely ham-fisted. The absence of pin 6 .......
166: Amp/Preamp Asylum, RE: Recommendations/Advice needed --Jensen Capacitor 0.10uF 630Vdc Copper Foil (Ceramic Case) (0.00)
Posted by Caucasian Blackplate on 2019-04-21, 07:49:23 (67.170.65.56)
Some of the older Jensen PIO caps had some reliability issues. If I had your power amp in my shop with these problems, I would be making the same recommendation. .......
167: Tube DIY Asylum, RE: Aluminum Power Transformer Covers (0.00)
Posted by Caucasian Blackplate on 2019-04-21, 07:40:09 (67.170.65.56)
How hard are you going to have this PT loaded? .......
168: General Asylum, What's "fully American" (0.00)
Posted by Caucasian Blackplate on 2019-04-20, 16:35:15 (67.170.65.56)
If a speaker company uses drivers sourced from abroad, is an amplifier American if it uses Chinese tubes? .......
169: Tubes Asylum, RE: Need To Develop A Short List Of Tubes For a BHK Pre Amp (0.00)
Posted by Caucasian Blackplate on 2019-04-20, 11:32:24 (172.58.47.92)
Look for big lots of random used tubes, the test and match them up as you go. There's a lot of love for the Mullard box plate 12AU7, but honestly I would just get 10-20 used old stock 6CG7s and try th .......
170: Tubes Asylum, RE: Need To Develop A Short List Of Tubes For a BHK Pre Amp (0.00)
Posted by Caucasian Blackplate on 2019-04-20, 09:36:33 (67.170.65.56)
That is helpful. There are some dubious products from overseas that claim you can just plug in what you want with no issues. The preamp looks to be designed for the 12AU7, so I would stick with the 12 .......
171: Tubes Asylum, RE: Need To Develop A Short List Of Tubes For a BHK Pre Amp (0.00)
Posted by Caucasian Blackplate on 2019-04-20, 09:11:38 (67.170.65.56)
"Need tubes for the pre amp, which can take 12a*7 family or 6922/6dj8 tubes." What is the actual preamp? (You don't mention a name or model number) A preamp that advertises that you can plug a 12AX7 o .......
172: Amp/Preamp Asylum, RE: Actually could use some help (0.00)
Posted by Caucasian Blackplate on 2019-04-20, 09:07:47 (67.170.65.56)
If you replace the main electrolytic caps in the amp, the value shouldn't go down. If you put nine million bypass caps in the amp and prospective buyers see that, I wouldn't count on getting full mark .......
173: Tube DIY Asylum, Other choices (0.00)
Posted by Caucasian Blackplate on 2019-04-19, 21:08:10 (67.170.65.56)
Using a pair of pentodes or two cascodes in the LTP would do the job too. .......
174: Amp/Preamp Asylum, RE: Asked them and they were very helpful (0.00)
Posted by Caucasian Blackplate on 2019-04-17, 17:55:01 (67.170.65.56)
No, I mean you could ask them if 47,000uF is going to be a problem. The ripple current rating is mostly a lifetime thing. .......
175: Amp/Preamp Asylum, RE: Just added the picture (0.00)
Posted by Caucasian Blackplate on 2019-04-17, 17:37:56 (172.58.44.79)
Since the manufacturer is still around and answering questions, you could certainly ask. .......
176: Amp/Preamp Asylum, RE: Changing Capacitors in Amplifier (0.00)
Posted by Caucasian Blackplate on 2019-04-17, 16:13:22 (67.170.65.56)
If you have old worn out caps, you're not going to experience a downgrade by replacing them. When I have to deal with this issue, I will buy what fits. Usually I find myself needing to go up in volta .......
177: Headphone Heights, RE: i thought about that but... (0.00)
Posted by Caucasian Blackplate on 2019-04-17, 07:41:51 (67.170.65.56)
I know for Sennheiser HD-580/600/650/6XX that this is very easily done at home. You may have to do a little research to see if it makes sense for your particular pair of headphones. .......
178: Headphone Heights, RE: an "oh crap" moment may have damaged my psb m4u 2 (0.00)
Posted by Caucasian Blackplate on 2019-04-16, 11:22:20 (67.170.65.56)
I would suggest just purchasing a replacement pair of drivers. .......
179: Tube DIY Asylum, RE: Knowledge Contributions Needed (0.00)
Posted by Caucasian Blackplate on 2019-04-16, 08:15:57 (67.170.65.56)
Your buyer will probably be more satisfied with an octal socket and a 6SN7. Your tube choices are a better engineering choice though. While the bipolar supply would get rid of a coupling cap, you coul .......
180: Amp/Preamp Asylum, RE: Two Different Amps And One Pair Of Speakers (0.00)
Posted by Caucasian Blackplate on 2019-04-15, 08:58:26 (67.170.65.56)
If you don't have an active crossover involved, it seems unlikely that you "have to" do this. One challenge that you'll face is that you need to trim the level of the higher gain amplifier to match th .......
181: Tube DIY Asylum, RE: Need a schematic expert (0.00)
Posted by Caucasian Blackplate on 2019-04-15, 08:44:53 (67.170.65.56)
That is the common method from the 60s and 70s, but not such a great way to go with modern headphones. .......
182: Amp/Preamp Asylum, RE: Continuous Average Power? (0.00)
Posted by Caucasian Blackplate on 2019-04-15, 07:42:55 (67.170.65.56)
It means that the RR2160 can dissipate sufficient heat to operate at those power levels indefinitely (assuming your room isn't too toasty). .......
183: SET Asylum, RE: Tube ot SS Rectification for 813?? (0.00)
Posted by Caucasian Blackplate on 2019-04-14, 13:04:27 (67.170.65.56)
I used to hold that same thought, but I've come to experience that this can be situationally dependent. Critical inductance sometimes takes a lot of copper to achieve, and when you go back to the volt .......
184: General Asylum, RE: Connecting a Mixer to a reciever with streaming abilities on twitch. (0.00)
Posted by Caucasian Blackplate on 2019-04-14, 12:40:35 (67.170.65.56)
You can split the signal from the main out and send it to one of the analog inputs on your receiver. There shouldn't be any degradation from doing this. Why are there so many isolators in your propose .......
185: Tube DIY Asylum, RE: Thanks - pretty persuasive argument for parafeed... (0.00)
Posted by Caucasian Blackplate on 2019-04-14, 12:35:41 (67.170.65.56)
So you went from a center-tapped choke with a parallel feed push-pull output transformer to just a push-pull line transformer? .......
186: SET Asylum, RE: Another Option (0.00)
Posted by Caucasian Blackplate on 2019-04-14, 10:35:41 (67.170.65.56)
I'm a fan of voltage doublers. .......
187: Tube DIY Asylum, RE: Examples of parafeed OPTs (0.00)
Posted by Caucasian Blackplate on 2019-04-14, 01:11:42 (67.170.65.56)
No typo, it just wants a relatively low drive impedance. .......
188: Tube DIY Asylum, RE: Thanks - pretty persuasive argument for parafeed... (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 17:46:39 (67.170.65.56)
You'll have to share some details of a differential preamp with a series feed OT. .......
189: Tube DIY Asylum, RE: Examples of parafeed OPTs (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 13:29:55 (67.170.65.56)
I would recommend buying something made to fit the job, especially with the advertised LF response of the Hammond. Looking at the schematic you posted, the Sowter 8940 is probably a better choice. I .......
190: Tube DIY Asylum, RE: Thanks - pretty persuasive argument for parafeed... (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 10:43:54 (172.58.44.41)
You'll also get extra psrr, but this shouldn't be that big of a deal if the design is adequately quiet with just the plate choke. .......
191: Tube DIY Asylum, RE: If you are going to do that (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 10:23:39 (172.58.44.41)
The parallel feed transformer will nearly always have better bandwidth. The plate choke will likely have more inductance than the primary of the gapped OT, and the coupling cap will be a smaller value .......
192: SET Asylum, RE: Another Option (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 09:50:28 (67.170.65.56)
I think you could do some breadboarding and answer this question for the particular circuit you have in mind. Low frequency response is largely dependent on the output transformer (and a circuit that' .......
193: SET Asylum, RE: Another Option (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 09:41:48 (67.170.65.56)
That's an option, but with your power supply voltage you will want that tube to be on its own winding. The 6CG3 is my normal recommendation. .......
194: SET Asylum, RE: Another Option (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 09:36:01 (67.170.65.56)
I'd rather have a solid state bridge rectifier, then put the 5AR4 between the output of the bridge and the first cap. You could also just use a single damper diode to do this job as well. .......
195: Tube DIY Asylum, RE: Suggest an output transformer? (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 09:33:01 (67.170.65.56)
Sure, here's one. For the balanced input, put a 100 ohm resistor between each secondary and ground. There's no need for a CT. .......
196: SET Asylum, RE: Another Option (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 09:11:46 (67.170.65.56)
Four per monoblock. They should be OK up to about 200mA of DC current draw with a cap input bridge rectified power supply like what you have drawn. .......
197: SET Asylum, RE: Another Option (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 08:45:15 (67.170.65.56)
They are both going to be about as out of the way as rectification can be. .......
198: Tube DIY Asylum, RE: Impedance matching - tube pre into SS amp..? (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 08:25:54 (67.170.65.56)
You could use a parallel feed line output transformer, then you can leave your plate choke and coupling cap in place. I wouldn't expect the solid state amp to load down your preamp too badly. ::: TOP .......
199: SET Asylum, Another Option (0.00)
Posted by Caucasian Blackplate on 2019-04-13, 08:07:13 (67.170.65.56)
These aren't inexpensive, but they would save some space and reduce the parts count substantially. For 1.2kV diodes, I'd still use 3. .......
200: Speaker Asylum, RE: Subwoofer finishing options (0.00)
Posted by Caucasian Blackplate on 2019-04-12, 09:09:08 (67.170.65.56)
Duratex works well. If you don't want to do it yourself, you can also take them to the local truck bed lining shop and have them sprayed with Line-X or Rhino Liner. .......
201: Headphone Heights, RE: using headphone with amp/preamp with no headphone socket (0.00)
Posted by Caucasian Blackplate on 2019-04-10, 12:31:14 (67.170.65.56)
Do you want to use these wirelessly? If so, you're going to compromise a lot by having Bluetooth between the music and the headphones. If you can possibly use the included headphone cable along with a .......
202: Tubes Asylum, RE: Transmitter Tube Stash (0.00)
Posted by Caucasian Blackplate on 2019-04-09, 21:11:50 (67.170.65.56)
The 849s are an extremely good score! .......
203: Tube DIY Asylum, RE: Resistor (0.00)
Posted by Caucasian Blackplate on 2019-04-09, 11:47:58 (67.170.65.56)
They look a bit like the IRC GS3 resistors, but the voltage rating is a not particularly spectacular. .......
204: Tube DIY Asylum, RE: Apparently altecboy and I both need to improve our writing skills (0.00)
Posted by Caucasian Blackplate on 2019-04-08, 16:30:25 (67.170.65.56)
That is pointing out that if you have a cathode biased push-pull amplifier, separate cathode resistors will go a long way toward balancing the DC operating points between tubes. The fixed bias operati .......
205: Tube DIY Asylum, RE: individual bias push pull output (0.00)
Posted by Caucasian Blackplate on 2019-04-06, 17:43:03 (67.170.65.56)
Is this presuming that the amplifier in question is cathode biased? I can't see a big difference in THD with two 1 ohm resistors vs. one 1 ohm resistor being used for idle current adjustment in a fixe .......
206: Speaker Asylum, RE: interested in PWK's measurement (0.00)
Posted by Caucasian Blackplate on 2019-04-06, 15:59:39 (67.170.65.56)
I'll have to go digging. It may have been IMD that he was looking at. .......
207: Tubes Asylum, RE: yES! (0.00)
Posted by Caucasian Blackplate on 2019-04-06, 11:33:26 (67.170.65.56)
I would absolutely not recommend using that first 12AX7 stage; you just aren't going to need it. .......
208: Speaker Asylum, RE: paper for 20kHz would cause problems other than THD (0.00)
Posted by Caucasian Blackplate on 2019-04-06, 10:50:05 (67.170.65.56)
Yes, the beaming will be terrible, and well below 20K to boot. I think PWK measured the distortion of the 901, and it was ridiculously high IIRC. .......
209: Speaker Asylum, RE: Bose has high: ±3 dB from just under 40 Hz to 20 kHz (0.00)
Posted by Caucasian Blackplate on 2019-04-06, 10:24:02 (67.170.65.56)
How do you suppose THD looks at 20kHz playing through those paper drivers? .......
210: Tubes Asylum, RE: I will bear that in mind! (0.00)
Posted by Caucasian Blackplate on 2019-04-05, 22:40:29 (67.170.65.56)
You'll have enough to deal with if you want to get the max power available from a push-pull circuit. Do you want me to dig out the Schematic for the little Bogen? .......
211: Tubes Asylum, RE: Yes, I'll mention that to Bill! (0.00)
Posted by Caucasian Blackplate on 2019-04-05, 18:53:06 (67.170.65.56)
That may be a big waste of parts and space. Are you going to do pentode push-pull with feedback? If so DC heaters are definitely a waste of time. .......
212: Tubes Asylum, RE: The OPTs in q'n are for P-P operation, and I would like to run the spkrs as well. (0.00)
Posted by Caucasian Blackplate on 2019-04-05, 18:28:45 (67.170.65.56)
What you want for headphone use is a 16 Ohm and 2 ohm resistor in series across the outputs, with the 2 ohm end grounded and the 16 ohm end at speaker +. Take headphone outs from the junction of each .......
213: Tubes Asylum, RE: Thanks for that. So Cathode bias will do, and a PT for such use is not going to be expensive, either. (0.00)
Posted by Caucasian Blackplate on 2019-04-05, 18:20:43 (67.170.65.56)
Don't go too big on the power transformer, you don't want to have 7V on the heaters because you aren't loading it down enough. .......
214: Tubes Asylum, RE: Would PP 6BM8 OPTs be up to driving 40 ohm phones and even a pair of near-field 8" 3-ways?! (0.00)
Posted by Caucasian Blackplate on 2019-04-03, 19:17:52 (67.170.65.56)
If you want pure class A, the bias winding isn't necessary. I have a little Bogen AC-220 that's a 6BM8 push-pull circuit. I think you'd be doing just fine with such a circuit to power headphones or re .......
215: MagneQuest/Peerless Forum, RE: Parafeed Baby O (0.00)
Posted by Caucasian Blackplate on 2019-04-01, 17:20:47 (172.58.40.54)
Looking good! .......
216: Speaker Asylum, RE: ATC Midrange Driver Repair Update - ProAc Studio 3 update (0.00)
Posted by Caucasian Blackplate on 2019-04-01, 15:09:13 (172.58.41.147)
I would send the drivers in for repair. Proac should be able to advise you on any necessary crossover modifications. .......
217: Tube DIY Asylum, RE: SE DC 6V6/6AQ5 : feedback & distortion study w/schematic. (0.00)
Posted by Caucasian Blackplate on 2019-03-31, 20:31:32 (67.170.65.56)
Q : should we be using feedback with SE tetrode/pentode finals? Yes. Q: would optimized wiring, cathode bypassing or formatting improve THD, IMD, bandwidth or other operating parameters of the above c .......
218: Tubes Asylum, RE: 6BM8s in SE triode mode for an OPT into headphones, Why? (0.00)
Posted by Caucasian Blackplate on 2019-03-31, 08:36:41 (67.170.65.56)
That 2000mW spec seems a bit comical to me, I would bet a few hundred mW would be plenty. For a triode straped 6BM8, a 5K-8K OT would be suitable, with high impedance headphone taps not being particul .......
219: Tube DIY Asylum, RE: OPT Response (0.00)
Posted by Caucasian Blackplate on 2019-03-30, 09:14:36 (67.170.65.56)
That's why I gave "5W at 80Hz" rather than -3dB at 80Hz ;) .......
220: Tube DIY Asylum, RE: 12SN7GTA versus 6BQ5 (EL84) in low power amp (0.00)
Posted by Caucasian Blackplate on 2019-03-29, 20:04:37 (67.170.65.56)
This is true for LF response, but the requirements for successfully driving dynamic headphones don't seem to necessitate a push-pull amplifier. .......
221: Tube DIY Asylum, RE: my 'phones go down to 20Hz, and I've checked on line. (0.00)
Posted by Caucasian Blackplate on 2019-03-29, 13:57:06 (67.170.65.56)
A transformer that saturates at 80Hz/5W is going to put out plenty of power at 20Hz into a pair of headphones. The output impedance at the headphone jack of your Luxman L3 is over 500 ohms, so not exa .......
222: Tube DIY Asylum, RE: 12SN7GTA versus 6BQ5 (EL84) in low power amp (0.00)
Posted by Caucasian Blackplate on 2019-03-29, 12:59:52 (67.170.65.56)
What is the similarity between a 6BQ5 and a 12SN7? (Other than that they are both vacuum tubes?) For headphone use, you don't need the expensive iron necessarily. Remember that transformer saturation .......
223: Tubes Asylum, RE: " no amount of tweaking is going to make a drastic difference like you seem to imply" (0.00)
Posted by Caucasian Blackplate on 2019-03-29, 07:54:21 (67.170.65.56)
You're telling a guy with a 20-ish year old amp not to "fall for the retubing advice". Do you see the issue here? .......
224: Tube DIY Asylum, RE: Update (0.00)
Posted by Caucasian Blackplate on 2019-03-28, 19:12:19 (67.170.65.56)
How about having them media blasted, then powder coated? .......
225: Tubes Asylum, " no amount of tweaking is going to make a drastic difference like you seem to imply" (0.00)
Posted by Caucasian Blackplate on 2019-03-28, 19:09:36 (67.170.65.56)
If the amp in question has really worn out tubes, it will make a drastic difference. .......
226: Tube DIY Asylum, RE: Poll (0.00)
Posted by Caucasian Blackplate on 2019-03-28, 12:57:25 (67.170.65.56)
You could put a coat of matte clear over the stainless to tone it down a little. .......
227: Tube DIY Asylum, RE: Resistor type (0.00)
Posted by Caucasian Blackplate on 2019-03-28, 11:18:08 (172.58.46.162)
Ah, sure, those small sizes are fine. I don't believe the tiny amount of inductance in those parts is going to cause any issues for most audio frequency amplifiers. If you happen to have a pentode run .......
228: Tube DIY Asylum, RE: Resistor type (0.00)
Posted by Caucasian Blackplate on 2019-03-28, 10:48:43 (172.58.46.162)
Why use such a large resistor in that position? .......
229: Tube DIY Asylum, RE: Resistor type (0.00)
Posted by Caucasian Blackplate on 2019-03-27, 19:01:18 (172.58.46.242)
Cathode bias resistors are typically bypassed, so AC signal current will nearly excluisvely go around the cathode resistor. For a plate loading resistor for a triode, those are probably fine too. If y .......
230: Tube DIY Asylum, RE: SE DC pentode/tetrode finals : separate g2 supplies ... (0.00)
Posted by Caucasian Blackplate on 2019-03-27, 17:52:04 (172.58.46.242)
Yeah, I don't understand the desire to build zero feedback SE pentode amps. This is certainly the worst case scenario for blowing up an output transformer when you disconnect a speaker, along with the .......
231: Amp/Preamp Asylum, RE: What do you think of radio wave impedance conversion? (0.00)
Posted by Caucasian Blackplate on 2019-03-27, 10:31:09 (67.170.65.56)
IMO, it's trading one set of challenges for a different set. If you have the opportunity, I would certainly have a listen! .......
232: Tube DIY Asylum, RE: SE DC pentode/tetrode finals : separate g2 supplies ... (0.00)
Posted by Caucasian Blackplate on 2019-03-27, 09:27:16 (67.170.65.56)
I remember being very surprised at how little G2 current changed in a SEP EL84 amp project some years ago. I bet if you simulated a 6550 running at the max operating point in the book, things would lo .......
233: Tube DIY Asylum, RE: Photos of DIY gone bad. (0.00)
Posted by Caucasian Blackplate on 2019-03-26, 08:03:49 (67.170.65.56)
That must smell pretty terrible. .......
234: General Asylum, RE: What components do others over and under spend on? (0.00)
Posted by Caucasian Blackplate on 2019-03-26, 07:01:44 (67.170.65.56)
I see lots and lots of five figure systems in rooms with no treatments. .......
235: Tubes Asylum, RE: Quicksilver KT88 mono amps (0.00)
Posted by Caucasian Blackplate on 2019-03-25, 18:56:49 (67.170.65.56)
It might be a good idea to try to connect with some locals who have tube gear. Someone may be able to loan you some tubes just to see if that's the issue. If the amps are nearing 15-20 years of age, o .......
236: Tubes Asylum, RE: Quicksilver KT88 mono amps (0.00)
Posted by Caucasian Blackplate on 2019-03-25, 18:40:47 (67.170.65.56)
How old are the amps? Do you have a complete spare set of tubes to try in the amps? .......
237: Amp/Preamp Asylum, RE: Response from Cary Audio (0.00)
Posted by Caucasian Blackplate on 2019-03-25, 15:51:40 (67.170.65.56)
Another inmate quoted a Stereophile article saying those numbers are about 10 times lower than the measured values. .......
238: Tube DIY Asylum, "Grab the fire extinguisher!" nt (0.00)
Posted by Caucasian Blackplate on 2019-03-25, 09:13:49 (67.170.65.56)
nt .......
239: General Asylum, RE: but wait, there's more (0.00)
Posted by Caucasian Blackplate on 2019-03-24, 19:26:14 (67.170.65.56)
That is super deep for what it is. That would be impossible to mount to a wall or to a TV. .......
240: General Asylum, RE: "Just add speakers" (0.00)
Posted by Caucasian Blackplate on 2019-03-24, 15:22:19 (67.170.65.56)
Smaller rooms are just where you would keep a record collection. .......
241: Amp/Preamp Asylum, RE: thanks to krisjan... (0.00)
Posted by Caucasian Blackplate on 2019-03-24, 11:54:18 (67.170.65.56)
Yeah, the tube output portion of that player is not at all intended to be used with a passive pre. .......
242: Tubes Asylum, RE: Can a NOS pair of 6SN7 blow a woofer? (0.00)
Posted by Caucasian Blackplate on 2019-03-23, 09:26:19 (67.170.65.56)
How did the woofer blow? Was it just sitting quietly then smoke started coming out, or was there a ton of low frequency noise that cooked it? .......
243: Amp/Preamp Asylum, RE: The Parasound... (0.00)
Posted by Caucasian Blackplate on 2019-03-22, 18:10:13 (67.170.65.56)
Low impedance is more difficult and often there's some capacitance at the input that isn't accounted for in those specs, so you'd want a source impedance under 3K at minimum. .......
244: Amp/Preamp Asylum, RE: the only spec listed... (0.00)
Posted by Caucasian Blackplate on 2019-03-22, 16:51:09 (67.170.65.56)
It's possible that it could be on the high side (2K-5K) and having some trouble drivi g your power amp, which very likely is a 10K load. I would borrow a preamp before making any purchasing decisions. .......
245: Amp/Preamp Asylum, RE: that thought has crossed my mind (0.00)
Posted by Caucasian Blackplate on 2019-03-22, 16:33:18 (67.170.65.56)
Do you know what the output impedance of your CD player is? (and what kind of drive current it has available) .......
246: Amp/Preamp Asylum, RE: brief update (0.00)
Posted by Caucasian Blackplate on 2019-03-22, 15:00:11 (67.170.65.56)
Why aren't you using a preamp? .......
247: Amp/Preamp Asylum, RE: 13 year old Musical Fidelity A5 Integrated (0.00)
Posted by Caucasian Blackplate on 2019-03-22, 08:33:22 (67.170.65.56)
I can't blame him for doing that, a lot of those "audiophile" parts are rather lacking in actual performance data! .......
248: Tube DIY Asylum, RE: These ixys HiPerFREDTM Epitaxial Diode with soft recovery any good? (0.00)
Posted by Caucasian Blackplate on 2019-03-22, 08:06:39 (67.170.65.56)
The 600V/1A schottky diodes are about $1, that doesn't seem like that big of a purchase. .......
249: Tube DIY Asylum, RE: Ground potential issue for tube gear? (0.00)
Posted by Caucasian Blackplate on 2019-03-21, 20:47:05 (67.170.65.56)
As TK mentioned, input impedance can play a reasonable role in what you're experiencing if it's not a matter of grounding differences. .......
250: Tubes Asylum, +1 nt (0.00)
Posted by Caucasian Blackplate on 2019-03-21, 18:15:43 (67.170.65.56)
nt .......
251: General Asylum, RE: Has high end audio progressed in 50 years? (0.00)
Posted by Caucasian Blackplate on 2019-03-21, 17:33:58 (67.170.65.56)
Everything is quantitatively better. We have significantly more materials to choose from for just about everything compared to 50 years ago. We have computers that can run reasonably accurate simulati .......
252: Amp/Preamp Asylum, RE: 13 year old Musical Fidelity A5 Integrated (0.00)
Posted by Caucasian Blackplate on 2019-03-21, 16:18:16 (67.170.65.56)
It is a good precaution to just have it recapped every 15 years or so. There's always someone with an old amp that says "my caps are fine" until the amp fails catastrophically or they get it serviced .......
253: Tube DIY Asylum, RE: Ground potential issue for tube gear? (0.00)
Posted by Caucasian Blackplate on 2019-03-21, 16:14:02 (67.170.65.56)
Do your source components have 3 wire plugs? What about the headphone amps in question? .......
254: Speaker Asylum, RE: Klipsch RF6 II Towers???? (0.00)
Posted by Caucasian Blackplate on 2019-03-21, 08:00:38 (67.170.65.56)
I would double check the model number, there doesn't seem to be an RF-6. .......
255: Speaker Asylum, RE: Midrange distortion (0.00)
Posted by Caucasian Blackplate on 2019-03-20, 08:24:15 (67.170.65.56)
Are those ferrofluid cooled drivers? I have seen plenty of ferrofluid get really nasty over time and it tends to result in lower output and some distortion. Nearly always it is just one driver out of .......
256: Amp/Preamp Asylum, RE: Reverse bi-wire: two channels into one . . . (0.00)
Posted by Caucasian Blackplate on 2019-03-20, 07:40:19 (67.170.65.56)
Kaboom indeed. .......
257: Amp/Preamp Asylum, RE: Solid state PRE ? (0.00)
Posted by Caucasian Blackplate on 2019-03-19, 11:45:43 (67.170.65.56)
There are plenty of situations where an active preamp is helpful and a passive is detrimental. .......
258: Amp/Preamp Asylum, RE: A simple explosive question (0.00)
Posted by Caucasian Blackplate on 2019-03-19, 07:15:35 (67.170.65.56)
For a whole lot of amps, doing what your friend suggested will just play the output of wherever you have the + channel. What you're looking for is an integrated amp with a mono switch, or you can put .......
259: Tube DIY Asylum, Nah, not really... (0.00)
Posted by Caucasian Blackplate on 2019-03-16, 17:01:19 (67.170.65.56)
"It sports 35 watt plate dissipation" The datasheet says 27. This is the same as the 6146B. "beefed up screen voltage" 6146B - 250V 6883B - 250V 6146 - 250V In fact, the datasheets for the 6146B and 6 .......
260: Tube DIY Asylum, RE: As Chauncey Gardner famously said, "I like to watch" (0.00)
Posted by Caucasian Blackplate on 2019-03-16, 09:58:20 (67.170.65.56)
Do you have the exact model number for the TV? It may have a bluetooth audio output, which isn't great, but it's totally usable. .......
261: Amp/Preamp Asylum, RE: Pinging Kal Rubinson, et al. - tube amp for the B&W 802D3? (0.00)
Posted by Caucasian Blackplate on 2019-03-15, 11:07:40 (67.170.65.56)
That is a pretty challenging load. It is 3 ohms from about 100Hz to 1kHz, which is a pretty wide swath of the overall bandwidth. You would really be well off looking for an amp with a 2 ohm tap *and* .......
262: General Asylum, RE: Would you use this? (0.00)
Posted by Caucasian Blackplate on 2019-03-14, 19:03:14 (67.170.65.56)
I would much rather have excess than have none at all. I have worked on three subwoofers recently from an absolutely beloved manufacturer of subwoofers, and none of them had this treatment to the boar .......
263: General Asylum, RE: Would you use this? (0.00)
Posted by Caucasian Blackplate on 2019-03-13, 11:05:00 (67.170.65.56)
Or they had to switch suppliers for a different glue. What would lead you to believe this is conductive? Have you taken out a meter to try and measure the electrical resistance of this material? I per .......
264: General Asylum, RE: Would you use this? (0.00)
Posted by Caucasian Blackplate on 2019-03-13, 10:41:15 (67.170.65.56)
That could just be some glue applied to certain parts of the PC board. This can be very helpful for a subwoofer where that board is going to see lots of vibrations. .......
265: Amp/Preamp Asylum, RE: Specs (0.00)
Posted by Caucasian Blackplate on 2019-03-12, 16:43:54 (67.170.65.56)
Gain is hardly in short supply in these circuits. The microphone jack in front could be converted to a 4PDT switch to accomplish the task of switching in and out the tone controls. Most components thi .......
266: Tube DIY Asylum, RE: My Don Allen P/P 2A3 amps - getting them back online. (0.00)
Posted by Caucasian Blackplate on 2019-03-12, 15:52:02 (67.170.65.56)
It's fun to see these brought back to life. I had a customer bring me a pair of the Webster double push-pull 2A3 amps. I measured that the transformer would end up being about 10K:8, so we opted to .......
267: Amp/Preamp Asylum, RE: Specs (0.00)
Posted by Caucasian Blackplate on 2019-03-12, 15:07:19 (67.170.65.56)
1500uF won't be 3dB down at 20Hz into an 8 ohm load, probably closer to 2dB ;) If you put signal in after the tone controls, how is the FR then? I sure would be measuring the resistors and caps in the .......
268: Tubes Asylum, RE: Tube curve traces - please interpret.... (0.00)
Posted by Caucasian Blackplate on 2019-03-12, 13:07:06 (67.170.65.56)
Well, you can always trace the circuit and measure the voltage, then the circuit can be adjusted for the tube you're interested in using. .......
269: SET Asylum, RE: Substitute 300B with WE275A (0.00)
Posted by Caucasian Blackplate on 2019-03-12, 12:42:03 (67.170.65.56)
It's hard to say whether only the 275A will fail, or whether it will take your amp with it. I would not use these in a 300B amp, many of the ratings of the 275A will be exceeded. .......
270: General Asylum, Fet? nt (0.00)
Posted by Caucasian Blackplate on 2019-03-12, 10:50:01 (67.170.65.56)
nt .......
271: Tubes Asylum, RE: Tube curve traces - please interpret.... (0.00)
Posted by Caucasian Blackplate on 2019-03-11, 21:10:27 (67.170.65.56)
Those draw a lot less plate current than a 6DJ8 would at a similar operating point. Without a schematic of the tube circuit used in the DAC, it's impossible to say whether they would work well. ::: TO .......
272: Tubes Asylum, RE: can't beat pair of China 12ax7 (0.00)
Posted by Caucasian Blackplate on 2019-03-11, 12:12:01 (172.56.42.200)
That's odd, I'd say about 80% of the untested used old stock tubes I have bought test and work fine. They also last infinitely longer than any Chinese tubes I've had. .......
273: Tubes Asylum, RE: can't beat pair of China 12ax7 (0.00)
Posted by Caucasian Blackplate on 2019-03-11, 09:13:13 (67.170.65.56)
Why not buy used old stock? .......
274: General Asylum, RE: Passive high-pass filter preserve zero feedback? (0.00)
Posted by Caucasian Blackplate on 2019-03-11, 08:49:09 (67.170.65.56)
If the crossover is passive (no batteries or power cable), then it has to be a zero feedback design. I think this is what you're asking. .......
275: Amp/Preamp Asylum, "However, the amplifier will still maintain 5.657-volts at its speaker terminals when the load changes from 8" (0.00)
Posted by Caucasian Blackplate on 2019-03-11, 08:46:01 (67.170.65.56)
"However, the amplifier will still maintain 5.657-volts at its speaker terminals when the load changes from 8-ohms to 4-ohms " Yes, it will, but if the transistors in the output stage are biased to be .......
276: Amp/Preamp Asylum, +1 nt (0.00)
Posted by Caucasian Blackplate on 2019-03-10, 10:10:12 (67.170.65.56)
nt .......
277: General Asylum, RE: High-pass filtering of amp output (0.00)
Posted by Caucasian Blackplate on 2019-03-08, 13:32:49 (67.170.65.56)
You are probably after a 4th order acoustical response, not necessarily a 4th order crossover. From the easiest to find measurements, it looks like you already have about a 2nd order rolloff happening .......
278: Amp/Preamp Asylum, RE: Tape output on Mark Levinson preamp a thing of the past? (0.00)
Posted by Caucasian Blackplate on 2019-03-07, 11:32:26 (67.170.65.56)
You went from using a headphone amp to making a recording... You could also split the output of your source. .......
279: Amp/Preamp Asylum, RE: Tape output on Mark Levinson preamp a thing of the past? (0.00)
Posted by Caucasian Blackplate on 2019-03-07, 10:35:36 (67.170.65.56)
Why not just use the pre-amp output of the 523? .......
280: Amp/Preamp Asylum, RE: Speaker Impedence / Amplifier Question (0.00)
Posted by Caucasian Blackplate on 2019-03-07, 07:47:32 (67.170.65.56)
If it doesn't mention 4 ohm operation, it's not very safe to assume that it will work. A lot of them will give a power rating and a 6-8 ohm impedance, and those aren't going to work too well either. J .......
281: Tube DIY Asylum, That is udderly hilarious nt (0.00)
Posted by Caucasian Blackplate on 2019-03-07, 07:45:27 (67.170.65.56)
nt .......
282: Tube DIY Asylum, RE: grid stoppers (0.00)
Posted by Caucasian Blackplate on 2019-03-07, 07:32:09 (67.170.65.56)
You need to get a scope or an FFT hooked up to your preamp so you can show us or describe exactly what noise you have. With the scope, you could probe the HV supply and filament supply to figure out .......
283: Amp/Preamp Asylum, RE: That's not always the case... (0.00)
Posted by Caucasian Blackplate on 2019-03-06, 13:37:21 (67.170.65.56)
There isn't a lot of info about the Reference 1, but a Stereophile review indicates that this is not a zero feedback circuit. This is not surprising considering the number of medium gain tubes are con .......
284: Amp/Preamp Asylum, RE: Speaker Impedence / Amplifier Question (0.00)
Posted by Caucasian Blackplate on 2019-03-06, 13:21:51 (67.170.65.56)
If you're going to pair a home theater receiver with lower impedance speakers, pay for weight. If you can find something like a Yamaha RX-V1 you'll be just fine. .......
285: Amp/Preamp Asylum, RE: That's not always the case... (0.00)
Posted by Caucasian Blackplate on 2019-03-06, 08:28:41 (67.170.65.56)
Which AR preamp do you have? Nearly all of the ones I have looked at use a fair amount of feedback, sometimes in interesting ways. .......
286: Headphone Heights, RE: My bet is on the Pass Labs... (0.00)
Posted by Caucasian Blackplate on 2019-03-05, 11:51:09 (67.170.65.56)
Do you know which Pass amp it's even a clone of? I think you're missing the point, you're using a stolen copy and claiming to evaluate the real product with it. There is some sketchy morality here. :: .......
287: Headphone Heights, RE: My bet is on the Pass Labs... (0.00)
Posted by Caucasian Blackplate on 2019-03-05, 07:46:04 (67.170.65.56)
It's a little effed up to take a Chinese counterfeiter's word that what they are selling is even a pass clone. .......
288: Tubes Asylum, RE: 6922 Tubes (0.00)
Posted by Caucasian Blackplate on 2019-03-04, 10:41:05 (67.170.65.56)
Kevin knows what he's talking about and provided you with the proper product. If you'd like new tubes for the Pathos, I would ask him what he recommends (he would very likely recommend something other .......
289: Tube DIY Asylum, RE: Kelvin Capacitors and Grounding (0.00)
Posted by Caucasian Blackplate on 2019-03-03, 14:55:59 (67.170.65.56)
The ground wire from the power cord should go to the chassis as close as possible to where the power cord enters the chassis. The star ground for the signal/power supply does not need to go here (and .......
290: Amp/Preamp Asylum, RE: gain (0.00)
Posted by Caucasian Blackplate on 2019-03-03, 13:23:39 (67.170.65.56)
Let's say I setup an active tube circuit with 60dB of gain and 60dB of feedback. Is that a buffer? What if I have a switch that makes it 59dB of feedback? The whole notion of a buffer for me would be .......
291: Tube DIY Asylum, RE: Kelvin Capacitors and Grounding (0.00)
Posted by Caucasian Blackplate on 2019-03-03, 13:22:00 (67.170.65.56)
If you're operating your transformer on 50Hz or 60Hz, you can wire the grounds of that cap together. If you have a switch mode power supply, I would suggest moving the star ground to the output of the .......
292: Amp/Preamp Asylum, RE: The designers intent! (0.00)
Posted by Caucasian Blackplate on 2019-03-03, 08:18:48 (67.170.65.56)
This isn't silly, part of the requirement for good performance from a preamp is reasonably low output impedance and reasonable drive current. .......
293: Amp/Preamp Asylum, RE: It's too new for me to get a schematic, but probably V1 provides input gain... (0.00)
Posted by Caucasian Blackplate on 2019-03-03, 08:17:13 (67.170.65.56)
How closely they need to be matched depends a lot on the impedance under the tail of the LTP. When push doesn't equal pull, the feedback network will correct for that. This doens't have a whole lot .......
294: Amp/Preamp Asylum, RE: Conrad Johnson Classic 62SE - What do the 6922 tubes do? And another question. (0.00)
Posted by Caucasian Blackplate on 2019-03-02, 15:51:09 (67.170.65.56)
"There are three 6922 tubes, V1, V2 and V3. What are the purposes of each of these tubes, e.g. input, inverter, driver, etc.?" It's most likely, in my opinion at least, that there is one 6922 that is .......
295: Amp/Preamp Asylum, RE: is this a real preamp or just a buffer? (0.00)
Posted by Caucasian Blackplate on 2019-03-01, 15:59:48 (73.35.218.226)
The Aikido boards don't have to be redesigned. .......
296: Tubes Asylum, RE: A lot of pots have its value as part of the part number (0.00)
Posted by Caucasian Blackplate on 2019-03-01, 14:00:24 (73.35.218.226)
The schematic just posted elsewhere in this thread shows a cathode biased amplifier, so there are no bias pots. .......
297: Amp/Preamp Asylum, RE: is this a real preamp or just a buffer? (0.00)
Posted by Caucasian Blackplate on 2019-03-01, 13:55:07 (73.35.218.226)
A lot of these circuits are clones of vintage preamp circuits, none of which are particularly well suited to modern hifi. .......
298: Amp/Preamp Asylum, RE: is this a real preamp or just a buffer? (0.00)
Posted by Caucasian Blackplate on 2019-03-01, 13:35:32 (73.35.218.226)
It probably has more gain than any sane person would want in a line-stage. I'd recommend some supplemental reading. .......
299: Amp/Preamp Asylum, RE: is this a real preamp or just a buffer? (0.00)
Posted by Caucasian Blackplate on 2019-03-01, 13:24:27 (73.35.218.226)
I think the references to this board as a "buffer" would just be a translation error. It would take a pretty severe effort to make a unity gain SRPP circuit (it is possible though) where a simple cat .......
300: Amp/Preamp Asylum, RE: is this a real preamp or just a buffer? (0.00)
Posted by Caucasian Blackplate on 2019-03-01, 13:09:18 (73.35.218.226)
What is the difference between a real preamp and a buffer? .......
301: Tubes Asylum, RE: A lot of pots have its value as part of the part number (0.00)
Posted by Caucasian Blackplate on 2019-03-01, 08:07:28 (73.35.218.226)
Hopefully we can get the rest of the schematic posted. These are not bias pots, they are hum balance pots. .......
302: Tubes Asylum, RE: Schematic (0.00)
Posted by Caucasian Blackplate on 2019-03-01, 08:02:47 (73.35.218.226)
Can you show the amp section too? .......
303: Tubes Asylum, RE: A lot of pots have its value as part of the part number (0.00)
Posted by Caucasian Blackplate on 2019-03-01, 07:37:50 (73.35.218.226)
I would post photos of the pots that you have. If they are rusty, it's possible that the resistance values aren't reliable. The schematic shows 25K for the hum balance pots, and that's what I would us .......
304: Tubes Asylum, RE: Question about tube pins (0.00)
Posted by Caucasian Blackplate on 2019-02-28, 17:35:22 (73.35.218.226)
I've actually done this successfully with a new production 300B once. The tube pins are hollow with a little hole at the end. If you hold the tube with the pins facing up, you can put your soldering i .......
305: Tubes Asylum, RE: A lot of pots have its value as part of the part number (0.00)
Posted by Caucasian Blackplate on 2019-02-28, 09:38:06 (73.35.218.226)
I have looked at all your previous posts, and I don't see that you ever posted photos of the actual parts. A few recent replies to this thread show that these are 25K pots. .......
306: Tubes Asylum, RE: A lot of pots have its value as part of the part number (0.00)
Posted by Caucasian Blackplate on 2019-02-27, 20:42:34 (73.35.218.226)
If it's a DC balance pot, then the value isn't super duper critical. A 500 ohm linear pot will work as a replacement. It's odd that there isn't an easily accessible schematic floating around. ::: TOPI .......
307: General Asylum, Link (0.00)
Posted by Caucasian Blackplate on 2019-02-27, 12:16:36 (172.58.43.141)
Link. .......
308: General Asylum, No (0.00)
Posted by Caucasian Blackplate on 2019-02-27, 11:52:09 (73.35.218.226)
When given the choice of filing a lawsuit or improving product quality in response to a poor review, Bose chose to lawyer up. .......
309: Tube DIY Asylum, RE: The case for a "real" scope... (0.00)
Posted by Caucasian Blackplate on 2019-02-27, 11:43:29 (73.35.218.226)
Sure, high GM driver tubes are one way to get there, though these are pretty uncommon in high voltage DHT amps. Still, the OP said he wanted to measure bandwidth and noise, not look for oscillations. .......
310: Tube DIY Asylum, RE: The case for a "real" scope... (0.00)
Posted by Caucasian Blackplate on 2019-02-27, 10:25:44 (172.58.43.141)
The OP mentioned an 845 amp, which is likely SET with little to no feedback and a transformer that isn't likely to get much over 25kHz. .......
311: Tube DIY Asylum, RE: oscilloscope buying advice. (0.00)
Posted by Caucasian Blackplate on 2019-02-27, 07:29:30 (73.35.218.226)
To measure bandwidth, you can use the Arta software package and a soundcard. I would recommend a 192kHz input/output card to maximize this functionality. You'll need an 8 ohm load for your amp, a 100 .......
312: Speaker Asylum, RE: Looking for a very specific tweeter (0.00)
Posted by Caucasian Blackplate on 2019-02-25, 15:43:40 (67.182.129.135)
Maybe it's a device to chase children away? It doesn't seem loud enough though. .......
313: Speaker Asylum, RE: Looking for a very specific tweeter (0.00)
Posted by Caucasian Blackplate on 2019-02-25, 11:23:33 (67.182.129.135)
So you want to be able to play a digital music file and only hear the treble? .......
314: Tube DIY Asylum, RE: OPT size question (0.00)
Posted by Caucasian Blackplate on 2019-02-25, 11:21:33 (67.182.129.135)
The question becomes a little more complicated for amps with feedback. For the case of an amp without feedback, you will have the primary inductance and magnetic saturation being limiting factors for .......
315: Tube DIY Asylum, RE: Triode USA still in business? (0.00)
Posted by Caucasian Blackplate on 2019-02-24, 09:37:18 (67.182.129.135)
The URL you posted is their old website. triodestore.com is the current URL. I have ordered a few times in the last year with no issues. .......
316: Tubes Asylum, RE: Working on early BOGEN JO/G/HO series amps (late 40s) (0.00)
Posted by Caucasian Blackplate on 2019-02-21, 19:55:49 (67.182.129.135)
I'm not sure why you're so insistent on running 813s. If you want a directly heated tube, the HY69 is much less of a stretch, especially considering that the cathode/filament is already grounded in th .......
317: Tubes Asylum, RE: Working on early BOGEN JO/G/HO series amps (late 40s) (0.00)
Posted by Caucasian Blackplate on 2019-02-21, 19:12:13 (67.182.129.135)
The HO50 looks to have an output transformer that's about a 2" tall stack on maybe EI105 lams. I think you would be surprised that a new production part from a quality winder would be about 50% larger .......
318: Tubes Asylum, RE: Working on early BOGEN JO/G/HO series amps (late 40s) (0.00)
Posted by Caucasian Blackplate on 2019-02-21, 17:59:14 (67.182.129.135)
I'd want to see measurements to believe anything you're posting. The cores in the HO125 look to be about the same size as your average 60W push-pull OT. 125W into 8 Ohms isn't quite 4A. Is this really .......
319: Tubes Asylum, RE: A lot of pots have its value as part of the part number (0.00)
Posted by Caucasian Blackplate on 2019-02-21, 14:24:54 (67.182.129.135)
A DC balance pot could certainly be 500 ohms. .......
320: Tubes Asylum, RE: A lot of pots have its value as part of the part number (0.00)
Posted by Caucasian Blackplate on 2019-02-21, 14:13:34 (67.182.129.135)
Is this a hum balance pot by chance? .......
321: Tubes Asylum, RE: A lot of pots have its value as part of the part number (0.00)
Posted by Caucasian Blackplate on 2019-02-21, 13:06:19 (67.182.129.135)
I wouldn't put a 500 ohm pot in there. I've never seen that low of a value in a vintage amp. The recommendations to disconnect one end of the pot (and the wiper) are good and may give you a more accur .......
322: Tubes Asylum, RE: Working on early BOGEN JO/G/HO series amps (late 40s) (0.00)
Posted by Caucasian Blackplate on 2019-02-21, 13:04:45 (67.182.129.135)
Yeah, the Sowters are $800, that's hardly the end of the world for what you're up to. 80W into 8 ohms is about 3A of current, is that really "whopping"? Are your amplifiers in a different building tha .......
323: Tubes Asylum, RE: Working on early BOGEN JO/G/HO series amps (late 40s) (0.00)
Posted by Caucasian Blackplate on 2019-02-21, 11:12:58 (67.182.129.135)
The hidden advantage of the low turns ratio disappears when you have to use two output transformers per amp, other than perhaps more flexibility in feedback implementation. If you're going to build up .......
324: Tubes Asylum, RE: Working on early BOGEN JO/G/HO series amps (late 40s) (0.00)
Posted by Caucasian Blackplate on 2019-02-21, 10:32:13 (67.182.129.135)
Your best bet would be to replace the output transformers with something else that doesn't have the taps for speaker distribution. I've done that with some CHB-100 monoblocks where one had a bad outpu .......
325: Tube DIY Asylum, RE: HY69 (0.00)
Posted by Caucasian Blackplate on 2019-02-21, 10:27:08 (67.182.129.135)
The 807 has twice the Gm of the HY69, and this will cause the triode curves to be quite different. Without attempting to make a Spice model, the HY69 datasheet has two sets of curves: one for the scre .......
326: Tube DIY Asylum, RE: ARC VT200 reading less at the 425 vdc lines (0.00)
Posted by Caucasian Blackplate on 2019-02-20, 18:30:57 (67.182.129.135)
When a 2.5kVA transformer is loaded with much less than 2.5kVA, the output voltage will creep up. This isn't surprising. What is surprising is that the raw unregulated B+ in your amp wasn't higher tha .......
327: Tube DIY Asylum, RE: Melody 3 stage M845 amp (0.00)
Posted by Caucasian Blackplate on 2019-02-20, 16:05:24 (67.182.129.135)
While you're thinking about your breadboard, you'll need to plunk some serious money down on output transformers. If you aren't prepared to spend $500-1000 on just the output transformers, then you'll .......
328: High Efficiency Speaker Asylum, RE: Disconnected (0.00)
Posted by Caucasian Blackplate on 2019-02-20, 08:34:13 (67.182.129.135)
If the crossover is connected to the output of a tube amp (other than maybe an OTL), I could rationalize seeing a near short there. Otherwise there is something amiss in the network. .......
329: General Asylum, RE: Are those Rubycon caps? (0.00)
Posted by Caucasian Blackplate on 2019-02-20, 08:33:18 (67.182.129.135)
Be sure to pay attention to the ripple current rating as well. .......
330: High Efficiency Speaker Asylum, RE: A little help with one channel down about 6dB please? (0.00)
Posted by Caucasian Blackplate on 2019-02-19, 14:46:36 (67.182.129.135)
The DCR between 2+ and 2- should be infinite, were you taking this measurement with the amplifier still connected? (powered on or off?) I would have a very, very close look at C5 to be sure it isn't s .......
331: Tubes Asylum, RE: pilot 240 bias pot value (0.00)
Posted by Caucasian Blackplate on 2019-02-19, 07:52:11 (67.182.129.135)
Why not take a meter and measure the ones in your amp? They will be linear pots, so just measure between the outside pair of lugs. .......
332: Tube DIY Asylum, RE: se 811a hum ploblem (0.00)
Posted by Caucasian Blackplate on 2019-02-18, 19:45:22 (67.182.129.135)
Well, if the hum is higher than 120Hz, then we would suspect a stability issue. Can you get a scope on the output to show what the waveform looks like? This can get you the frequency and amplitude, wh .......
333: Tube DIY Asylum, RE: se 811a hum ploblem (0.00)
Posted by Caucasian Blackplate on 2019-02-18, 08:37:26 (67.182.129.135)
Are you AC heating the 811 tubes? How much feedback in the design? (possibly post a schematic) Is this a new problem/new build? or an old build with a new problem? I've built 4 or 5 sets of 811 mon .......
334: Tube DIY Asylum, RE: reality check (0.00)
Posted by Caucasian Blackplate on 2019-02-17, 13:06:02 (67.182.129.135)
It looks like you should try 800V/110mA and a proper output transformer. .......
335: SET Asylum, RE: 2A3 Direct Coupled VS. Capacitor coupled (0.00)
Posted by Caucasian Blackplate on 2019-02-16, 18:24:38 (172.58.46.136)
Yeah, those are intelligently designed for the purpose. .......
336: SET Asylum, RE: "they tend to force a pretty high plate voltage onto your driver stage." ? (0.00)
Posted by Caucasian Blackplate on 2019-02-16, 13:53:24 (172.58.46.136)
Yes, you can certainly do that. It is a bit inelegant to dump a plate loading resistor, only to put it back in the form of a power supply dropping resistor (just my opinion of course). Interstage tran .......
337: Amp/Preamp Asylum, RE: new Marantz or old Arcam (0.00)
Posted by Caucasian Blackplate on 2019-02-16, 10:52:45 (67.182.129.135)
Your concern about the age of the Arcam could be valid, it's within the window of needing a recap. .......
338: Speaker Asylum, RE: Will you buy these speakers... (0.00)
Posted by Caucasian Blackplate on 2019-02-16, 10:41:58 (67.182.129.135)
You can get new Dynaco A25 speakers. .......
339: SET Asylum, RE: 2A3 Direct Coupled VS. Capacitor coupled (0.00)
Posted by Caucasian Blackplate on 2019-02-16, 10:10:46 (67.182.129.135)
If you eliminate the capacitor and the grid leak resistor that follows it, the grid of the 2A3 is now elevated well above ground. The DC bias voltage at the filament is now higher (and the biasing res .......
340: Tube DIY Asylum, RE: ARC VT200 reading less at the 425 vdc lines (0.00)
Posted by Caucasian Blackplate on 2019-02-15, 15:40:17 (67.182.129.135)
What AC voltage do you see coming out of your isolation transformer without the amp powered up? How about with the amp powered up? (after the warmup relay closes) .......
341: Tube DIY Asylum, RE: ARC VT200 reading less at the 425 vdc lines (0.00)
Posted by Caucasian Blackplate on 2019-02-15, 13:04:53 (67.182.129.135)
I would bet on a loose connection related to the isolation transformer, unless you have a ton of gear loading it down. .......
342: Tube DIY Asylum, RE: ARC VT200 reading less at the 425 vdc lines (0.00)
Posted by Caucasian Blackplate on 2019-02-15, 12:09:51 (172.58.43.148)
Next I would check the AC voltage coming out of the ISO transformer with the amp off, then the amp on. Also, can you confirm that your ISO transformer is the 7500VA one? .......
343: Amp/Preamp Asylum, RE: 220V amp on 110V socket (0.00)
Posted by Caucasian Blackplate on 2019-02-15, 11:26:54 (67.182.129.135)
I would recommend opening it up and posting some photos. It may have been rewired for 110V operation. .......
344: Tube DIY Asylum, RE: ARC VT200 reading less at the 425 vdc lines (0.00)
Posted by Caucasian Blackplate on 2019-02-15, 11:07:55 (172.58.43.148)
A 7.5KVA isolation transformer is going to cause higher B+. (you've noted 124V coming out of it, which makes sense since you can't load it down enough to get back to 120V). You've received some bum te .......
345: Tube DIY Asylum, RE: ARC VT200 reading less at the 425 vdc lines (0.00)
Posted by Caucasian Blackplate on 2019-02-15, 10:16:35 (67.182.129.135)
That's not really a satisfactory answer. What's "Topaz"? There are some current limiting components ahead of the power transformer and a relay that shorts across all of them after a predetermined amo .......
346: Tube DIY Asylum, RE: ARC VT200 reading less at the 425 vdc lines (0.00)
Posted by Caucasian Blackplate on 2019-02-14, 22:06:27 (67.182.129.135)
The service manual is dated 1997, so you might want to see if there's a production date anywhere on your amp. .......
347: Tube DIY Asylum, RE: ARC VT200 reading less at the 425 vdc lines (0.00)
Posted by Caucasian Blackplate on 2019-02-14, 21:07:24 (67.182.129.135)
How old are the capacitors in your VT-200? As they fail, your raw rail voltage may start dropping. .......
348: Tube DIY Asylum, RE: ARC VT200 reading less at the 425 vdc lines (0.00)
Posted by Caucasian Blackplate on 2019-02-14, 14:51:47 (67.182.129.135)
The HV rails that aren't the 420V rails are regulated, so the available voltage would have to fall a lot to influence those supplies. What is your AC line voltage? .......
349: Tubes Asylum, RE: Optimal EL84 operating point for UL pentode mode (0.00)
Posted by Caucasian Blackplate on 2019-02-14, 13:00:38 (67.182.129.135)
Yes, the low loading operation. The graph gives distortion vs. power curves for three different options, with one of them being the lower impedance output transformer. It shows 18W at 2% THD. Distribu .......
350: Tubes Asylum, RE: Optimal EL84 operating point for UL pentode mode (0.00)
Posted by Caucasian Blackplate on 2019-02-14, 11:29:51 (67.182.129.135)
If you click the link, it shows you how to do a Google search for "Mullard 5-10". If you perform the search as show, the second result is the article. .......
351: Tube DIY Asylum, RE: confused again (0.00)
Posted by Caucasian Blackplate on 2019-02-13, 15:40:30 (67.182.129.135)
It will be a lot less confusing if you have a coupling cap. The grid of the output tube will be at 0V DC, then you can bias up the cathode accordingly. Direct coupling means that you are relying on th .......
352: Tube DIY Asylum, RE: confused again (0.00)
Posted by Caucasian Blackplate on 2019-02-13, 15:25:29 (67.182.129.135)
Why what? .......
353: Tube DIY Asylum, RE: confused again (0.00)
Posted by Caucasian Blackplate on 2019-02-13, 15:17:18 (67.182.129.135)
The formula for a cathode resistor is Ohm's Law (if you know bias voltage and idle current). Based on the schematic you posted at the start of this thread, do be sure to include a coupling capacitor a .......
354: Speaker Asylum, RE: Tweeter cap (0.00)
Posted by Caucasian Blackplate on 2019-02-13, 09:40:17 (67.182.129.135)
Yeah, you would have to put two of the polar caps in series, which may present a space problem. depending on the crossover design, you may be able to free up the inductor and move the cap and inducto .......
355: Speaker Asylum, RE: Tweeter cap (0.00)
Posted by Caucasian Blackplate on 2019-02-13, 09:24:01 (67.182.129.135)
So you probably also need an axial leaded capacitor instead of a radial leaded cap for that application? If you need an axial cap, Sprague Atom and Nichicon TVX are probably going to fit fine to repla .......
356: Tube DIY Asylum, RE: confused again (0.00)
Posted by Caucasian Blackplate on 2019-02-13, 09:12:37 (67.182.129.135)
If you have 370V on the plate and 19V on the cathode, your plate to cathode voltage is 351. If you want 51V of bias and 64mA of plate current, that is a 796 ohm cathode bias resistor. If you want 430V .......
357: SET Asylum, RE: PX25 tube....educate me. (0.00)
Posted by Caucasian Blackplate on 2019-02-13, 07:45:38 (67.182.129.135)
He's throwing his money away. You should try to buy his used tubes with 500 hours on them! .......
358: SET Asylum, RE: PX25 tube....educate me. (0.00)
Posted by Caucasian Blackplate on 2019-02-13, 07:21:37 (67.182.129.135)
More like 5000-10000 hours. The PX25A probably won't work well in the amp, but any normal PX25 should be OK. .......
359: SET Asylum, RE: do you mean px4? (0.00)
Posted by Caucasian Blackplate on 2019-02-11, 14:10:29 (67.182.129.135)
The PX4 and the 45 are similar in a fair number of ways, though the PX4 is a bit easier to work with. FWIW, the 2A3 plate dissipation rating seems a bit mysterious, and I don't hesitate to push well a .......
360: SET Asylum, RE: PX25 tube....educate me. (0.00)
Posted by Caucasian Blackplate on 2019-02-11, 12:41:27 (67.182.129.135)
If you ran the amp 2-3 hours per day 5 days per week, they shouldn't last any longer than about 8 years. .......
361: SET Asylum, RE: PX25 tube....educate me. (0.00)
Posted by Caucasian Blackplate on 2019-02-11, 10:52:49 (67.182.129.135)
It wouldn't surprise me if a 300B or 2A3 from the same company sounded a bit better. I keep reading this sentence in all the reviews: "The slightly higher plate resistance, relative to a 300B, allowed .......
362: Tubes Asylum, RE: Optimal EL84 operating point for UL pentode mode (0.00)
Posted by Caucasian Blackplate on 2019-02-11, 10:25:27 (67.182.129.135)
See the second result. .......
363: SET Asylum, RE: PX25 tube....educate me. (0.00)
Posted by Caucasian Blackplate on 2019-02-11, 09:34:01 (67.182.129.135)
You get to make some tough choices if you go down the PX25 road. The NOS tubes and the new production tubes fit in different sockets. I think you mentioned all of the current producers. My struggle w .......
364: Amp/Preamp Asylum, RE: Manual (0.00)
Posted by Caucasian Blackplate on 2019-02-10, 17:49:28 (67.182.129.135)
I found this in the product literature for these receivers. Sony can be pretty nebulous with things like operational diagrams, but it's entirely likely that the receiver you have is class D. Even .......
365: General Asylum, RE: Grammy's (0.00)
Posted by Caucasian Blackplate on 2019-02-10, 17:27:41 (67.182.129.135)
When I heard Hozier sing with Annie Lennox for the 2015 Grammy Awards, I threw in the towel on watching any thereafter. It would be a good advertisement for auto-tune though... .......
366: Tube DIY Asylum, RE: 813 set schematic (0.00)
Posted by Caucasian Blackplate on 2019-02-10, 15:28:37 (67.182.129.135)
Without a coupling cap and grid leak, you will blow up the cathode resistor you've selected. The filament supply may or may not also explode, and it will depend enormously on the parts you've selected .......
367: Tubes Asylum, RE: Optimal EL84 operating point for UL pentode mode (0.00)
Posted by Caucasian Blackplate on 2019-02-10, 15:20:40 (67.182.129.135)
Check out the Mullard article, there is a very interesting hint in there about getting better performance by deviating significantly from "the norm" in terms of EL84 operating points. .......
368: Amp/Preamp Asylum, Manual (0.00)
Posted by Caucasian Blackplate on 2019-02-10, 09:22:16 (67.182.129.135)
Here's the 80 page manual, read up! .......
369: Amp/Preamp Asylum, RE: Thoughts and opinion on ATI 1505- 5 Channel Power Amplifier (0.00)
Posted by Caucasian Blackplate on 2019-02-09, 12:40:16 (67.182.129.135)
These are getting to be old enough that you'll want to have whatever you buy serviced to at least replace the power supply caps and just give everything a look over. It's hard to say what these are g .......
370: Tubes Asylum, RE: Optimal EL84 operating point for UL pentode mode (0.00)
Posted by Caucasian Blackplate on 2019-02-09, 12:31:29 (67.182.129.135)
I'm not really a fan of "a pile of 12AX7s and some EL84s", so the Eico would be out for me. There isn't a lot of info available about the SA-240, but I suspect it's in the same boat. The SCA-35 is a .......
371: Tube DIY Asylum, RE: Audio Research SP6B PSU problem (0.00)
Posted by Caucasian Blackplate on 2019-02-09, 11:39:44 (67.182.129.135)
Well, if this is your own personal unit, you could consider some dramatic simplifications of that power supply if does keep failing. .......
372: Tube DIY Asylum, RE: Audio Research SP6B PSU problem (0.00)
Posted by Caucasian Blackplate on 2019-02-09, 09:44:16 (67.182.129.135)
I always suspect the zener diodes when anything is wrong in an AR preamp power supply. Are you sure Q6 is good? If Q6 shorts, that would certainly explain Q4 and Q5 dying. ZD6 and ZD3 would die in the .......
373: Speaker Asylum, RE: Question About Motor Run Cap In Crossover (0.00)
Posted by Caucasian Blackplate on 2019-02-09, 08:43:41 (67.182.129.135)
I wouldn't bother with the bypass cap. .......
374: Tubes Asylum, RE: Optimal EL84 operating point for UL pentode mode (0.00)
Posted by Caucasian Blackplate on 2019-02-09, 08:05:21 (67.182.129.135)
When you're building class AB P-P, consider how much power you need! Always use fixed bias if at all possible for this kind of amp. Your transitions into class B will be more graceful and the amp wil .......
375: Speaker Asylum, RE: Question About Motor Run Cap In Crossover (0.00)
Posted by Caucasian Blackplate on 2019-02-08, 14:32:04 (67.182.129.135)
What voltage rating is that 120uF cap? I have only really seen that on very high voltage caps. Your speaker crossover isn't going to function any differently with the resistor there. .......
376: Amp/Preamp Asylum, RE: When to recapped the power supply of a tube power amp (0.00)
Posted by Caucasian Blackplate on 2019-02-06, 19:45:26 (67.182.129.135)
For every 10C you go down, lifetime doubles. 3000 hours at 105C 6000 hours at 95C 12000 hours at 85C 24000 hours at 75C 48000 hours at 65C 96000 hours at 55C 192000 hours at 45C 384000 hours at 35C T .......
377: Amp/Preamp Asylum, RE: When to recapped the power supply of a tube power amp (0.00)
Posted by Caucasian Blackplate on 2019-02-06, 19:21:27 (67.182.129.135)
Your amplifier manufacturer was thoughtful enough to put those caps outside where they can stay nice and cool. You can also keep an eye on the tops to look for bulging. How much do you use these amps .......
378: Speaker Asylum, RE: Suggestions for mounting baffles holding Altec 604e drivers (0.00)
Posted by Caucasian Blackplate on 2019-02-06, 13:00:04 (67.182.129.135)
What does the front of the cabinet look like? .......
379: Amp/Preamp Asylum, RE: Amplifier output in shotgun bi-wire configuration (0.00)
Posted by Caucasian Blackplate on 2019-02-06, 12:58:06 (67.182.129.135)
Let's assume you have a 2 way speaker with a crossover frequency of 2.5kHz. . If you play a 100Hz test tone at full power, almost all of it will appear at the terminus of the cable pair going to the .......
380: Amp/Preamp Asylum, RE: Yamaha A-S1100 Integrated in the House - pics (0.00)
Posted by Caucasian Blackplate on 2019-02-05, 17:43:54 (67.182.129.135)
It's really nice to see that they didn't put a DAC in it. This will be as timeless as a vintage unit. .......
381: Speaker Asylum, RE: Vintage Fisher XP-9C Speakers (0.00)
Posted by Caucasian Blackplate on 2019-02-03, 21:18:27 (67.182.129.135)
I use this stuff on vintage cabinets. Usually I apply it with the smoothest steel wool I can find. If it won't take out all the marks, then you'll have to carefully sand and refinish. .......
382: Tubes Asylum, RE: I wonder if they still honor this? (0.00)
Posted by Caucasian Blackplate on 2019-02-03, 10:16:18 (67.182.129.135)
You better be careful, they may just sign Radio Shack over to you if you try to make them honor the warranty. .......
383: Headphone Heights, RE: Does matching a 300 ohm headphone with a.... (0.00)
Posted by Caucasian Blackplate on 2019-02-03, 10:04:43 (67.182.129.135)
This depends a little bit on the amp. I have not seen a headphone amp that has an actual 300 ohm output impedance (this is not the same as a 300 ohm tap on the output transformers). Based on seeing t .......
384: Amp/Preamp Asylum, RE: Signal to noise ratio basic....total novice here need some help (0.00)
Posted by Caucasian Blackplate on 2019-02-02, 08:50:01 (67.182.129.135)
"1 when looking at a reciver's S/N ratio what does the (mm), and (line) reffer to Signal to noise ratio: 70dB (MM), 90dB (line)" MM would be a moving magnet phono cartridge input and line would be th .......
385: Tubes Asylum, RE: Lundahl 2765-30ma trnsformer (0.00)
Posted by Caucasian Blackplate on 2019-02-01, 21:44:12 (67.182.129.135)
The airgap is set when the transformer is manufactured and it's not easily adjustable (you'd probably destroy the transformer trying). Since yours indicate 30mA, they are suitable to be used between B .......
386: Amp/Preamp Asylum, RE: complex xover = more power required? (0.00)
Posted by Caucasian Blackplate on 2019-02-01, 21:39:13 (67.182.129.135)
"All of those passive components absorb energy or redirect it to ground (that's their only role), so obviously one needs more power at the input if so much of it gets wasted." How much power would a 4 .......
387: Amp/Preamp Asylum, RE: Anyone experience getting over the power hump ? (0.00)
Posted by Caucasian Blackplate on 2019-02-01, 20:11:46 (67.182.129.135)
"Therefore, it should work on the 4-ohm tap of a tube amplifier just as well as on the 2-ohm tap. The best part about its impedance curve is that it's very flat." If sufficient power is available, the .......
388: Amp/Preamp Asylum, RE: Anyone experience getting over the power hump ? (0.00)
Posted by Caucasian Blackplate on 2019-02-01, 11:15:55 (67.182.129.135)
For a class A solid state amplifier optimized for an 8 ohm load, using it on your 3 ohm speakers really calls for some mods. One would want to decrease the power supply rails and increase the idle cur .......
389: Amp/Preamp Asylum, RE: Anyone experience getting over the power hump ? (0.00)
Posted by Caucasian Blackplate on 2019-02-01, 10:27:08 (67.182.129.135)
I remember running into this with some Apogee Caliper Signatures. I had VTL-225 monoblocks initially, then switched out to a McIntosh MC-2500. The extra beef from the McIntosh really opened up those s .......
390: Amp/Preamp Asylum, RE: Fisher MC-2100 vs ONKYO TX-830 (0.00)
Posted by Caucasian Blackplate on 2019-02-01, 09:42:59 (172.56.42.166)
Either one should get some fresh power supply caps though! .......
391: Amp/Preamp Asylum, RE: Fisher MC-2100 vs ONKYO TX-830 (0.00)
Posted by Caucasian Blackplate on 2019-02-01, 09:19:03 (67.182.129.135)
Ah, I see it now. I wouldn't be surprised if the Onkyo is significantly better than the Fisher in just about every conceivable way aside from cosmetically. .......
392: Amp/Preamp Asylum, RE: Fisher MC-2100 vs ONKYO TX-830 (0.00)
Posted by Caucasian Blackplate on 2019-02-01, 07:55:59 (67.182.129.135)
The MC-2100 has some small STK modules in the amplifier section. It's a 10-15W audio amplifier integrated circuit, and not that great of one. Is the Onkyo a TX-SR308? .......
393: Tube DIY Asylum, RE: paralleled 6sl7? (0.00)
Posted by Caucasian Blackplate on 2019-01-31, 07:53:27 (67.182.129.135)
Just wire the pins together at the socket. .......
394: Tube DIY Asylum, RE: paralleled 6sl7? (0.00)
Posted by Caucasian Blackplate on 2019-01-31, 07:12:40 (67.182.129.135)
Here are the steps: 1. Wire plate 1 in parallel with plate 2. 2. Wire grid 1 in parallel with grid 2. 3. Wire cathode 1 in parallel with cathode 2. .......
395: Amp/Preamp Asylum, RE: ARE YOU TRASHIN' MY METER ???? (0.00)
Posted by Caucasian Blackplate on 2019-01-30, 21:30:57 (172.56.42.35)
The transformers in question are not potted. They are undoubtedly varnished in a vacuum chamber, but this is noise coming out of the speakers, not a buzzy TX. .......
396: Amp/Preamp Asylum, RE: ARE YOU TRASHIN' MY METER ???? (0.00)
Posted by Caucasian Blackplate on 2019-01-30, 14:21:41 (67.182.129.135)
Nah, not trashing it. My Fluke can barely resolve a noise level that low reliably. Oddly enough the better meter at Harbor freight seems to do a better job. .......
397: Amp/Preamp Asylum, RE: I have a Greenlee (0.00)
Posted by Caucasian Blackplate on 2019-01-30, 14:02:32 (67.182.129.135)
The AC voltage scale doesn't quite go low enough on that meter to resolve 1mV. .......
398: Amp/Preamp Asylum, RE: That's above my pay grade (0.00)
Posted by Caucasian Blackplate on 2019-01-30, 13:34:07 (67.182.129.135)
If you have a sensitive DVM, you can set it to AC volts (or millivolts if available) and measure what's coming out of the binding posts with no music playing. .......
399: Amp/Preamp Asylum, RE: After seeing all those fancy amps below........... (0.00)
Posted by Caucasian Blackplate on 2019-01-30, 13:00:57 (67.182.129.135)
This is not necessarily abnormal, but the specs for the VT-60 give noise as less than 500uV. This measurement is weighted, unfortunately, so that doesn't really help as much as an unweighted measureme .......
400: Tubes Asylum, RE: I don't, I replace them when I need to. (0.00)
Posted by Caucasian Blackplate on 2019-01-30, 11:10:34 (67.182.129.135)
My annual income would drop considerably if people stopped tube rolling! (from replacing sockets and other associated damage from putting the wrong tube into the wrong socket) .......
401: Speaker Asylum, RE: Outboard Active vs Inboard Pasive xovers - preference? (0.00)
Posted by Caucasian Blackplate on 2019-01-30, 11:07:07 (67.182.129.135)
"You don't think that the reactive load of a passive crossover isn't more prone to sonic affects than the low level circuits of an active crossover?" Man, that's such a complicated question to properl .......
402: General Asylum, RE: USPS follies (0.00)
Posted by Caucasian Blackplate on 2019-01-30, 07:54:01 (67.182.129.135)
My original response: When the package stops moving, it's so much easier to print out the tracking history and hand it to your delivery driver rather than calling in and sitting on hold or waiting in .......
403: General Asylum, RE: USPS follies (0.00)
Posted by Caucasian Blackplate on 2019-01-30, 06:47:55 (67.182.129.135)
When the package stops moving, it's so much easier to print out the tracking history and hand it to your delivery driver rather than calling in and sitting on hold or waiting in line at the counter. : .......
404: General Asylum, RE: Same here... (0.00)
Posted by Caucasian Blackplate on 2019-01-29, 18:23:47 (67.182.129.135)
Oops, I haven't been 24 in a while! .......
405: General Asylum, RE: USPS follies (0.00)
Posted by Caucasian Blackplate on 2019-01-29, 16:10:38 (67.182.129.135)
The absolute most helpful thing I have done in these situations is to make friends with all my delivery drivers. My USPS lady and I are on a first name basis, and the UPS guy is close behind. They get .......
406: Tube DIY Asylum, RE: How to calculate current based on the sum of AC and DC voltages (0.00)
Posted by Caucasian Blackplate on 2019-01-29, 16:04:07 (67.182.129.135)
PSUD can be helfpul with this. There's AC current in that first filter cap that you have to figure into the rating as well. You can also work backwards from the Hammond Design Guide for Rectifier Use .......
407: Tube DIY Asylum, RE: Please check my diode choices (0.00)
Posted by Caucasian Blackplate on 2019-01-27, 14:04:13 (67.182.129.135)
Why do you want to change out the diodes? You're going to have a rough time replacing axial diodes with TO-220 diodes. Even if you bend the legs all the way out, they may not reach the holes on the P .......
408: Speaker Asylum, RE: I need to stand up if I want to hear bass (0.00)
Posted by Caucasian Blackplate on 2019-01-27, 12:11:50 (67.182.129.135)
Curtains aren't going to do a whole lot, especially at low frequencies. Maybe there's an unused bedroom available? .......
409: Speaker Asylum, RE: I need to stand up if I want to hear bass (0.00)
Posted by Caucasian Blackplate on 2019-01-27, 11:27:03 (67.182.129.135)
It's usually not a great idea, but you may want to try rotating your system 90 degrees so the speakers are along the wall with the window. You're going to need to treat that room, and treat it a lot! .......
410: Speaker Asylum, RE: I need to stand up if I want to hear bass (0.00)
Posted by Caucasian Blackplate on 2019-01-27, 11:12:05 (67.182.129.135)
What's on the wall behind the furniture? That's a difficult area to treat, especially with the door in the corner. .......
411: Speaker Asylum, RE: I need to stand up if I want to hear bass (0.00)
Posted by Caucasian Blackplate on 2019-01-27, 09:00:57 (67.182.129.135)
Can you post photos of the room/setup? This issue is likely resolvable with appropriate room treatments to keep that suck out from developing where you're sitting. .......
412: Tube DIY Asylum, RE: Dynaco ST-70 in Triode Mode (0.00)
Posted by Caucasian Blackplate on 2019-01-26, 19:56:51 (67.182.129.135)
Now you just have to modify it for the 6B4G :) .......
413: Amp/Preamp Asylum, RE: Amp Pictures - post yours (0.00)
Posted by Caucasian Blackplate on 2019-01-26, 15:56:46 (67.182.129.135)
New project. .......
414: Tube DIY Asylum, RE: Mu stage question (0.00)
Posted by Caucasian Blackplate on 2019-01-26, 10:56:12 (67.182.129.135)
There are four caps in there. The coupling cap and the cap at the output would be in a tie for me for the most important, with an almost tie going to the cathode bypass cap, and the screen bypass cap .......
415: Amp/Preamp Asylum, RE: pic of PV8 (0.00)
Posted by Caucasian Blackplate on 2019-01-25, 08:49:14 (67.182.129.135)
It's hard to say. If they had a photo of the bottom traces on the board, things would make a lot more sense. Looking more carefully at what's there, none of the triodes are in parallel with each other .......
416: Amp/Preamp Asylum, RE: pic of PV8 (0.00)
Posted by Caucasian Blackplate on 2019-01-25, 07:19:38 (67.182.129.135)
If you look at the board carefully, this is not the case. .......
417: Amp/Preamp Asylum, RE: pic of PV8 (0.00)
Posted by Caucasian Blackplate on 2019-01-24, 22:43:06 (67.182.129.135)
Yes, precisely. .......
418: Tube DIY Asylum, RE: CBB60/CBB61 polypropylene motor run caps (0.00)
Posted by Caucasian Blackplate on 2019-01-24, 20:39:47 (67.182.129.135)
Broskie's article warns about putting constant current sources in series. .......
419: Tube DIY Asylum, RE: CBB60/CBB61 polypropylene motor run caps (0.00)
Posted by Caucasian Blackplate on 2019-01-24, 18:55:36 (67.182.129.135)
These are probably just fine for coupling caps. 47uF is an odd value for a coupling cap though, it's way too low for a power amp, still on the low side for a headphone amp, and way too high for a pre .......
420: Amp/Preamp Asylum, RE: to conrad-johnson pv8/9 connoisseurs (0.00)
Posted by Caucasian Blackplate on 2019-01-24, 12:22:24 (67.182.129.135)
Well, the PV-8 uses two triodes per channel for the linestage. This would be one tube per channel, and it would NEVER be a 12AX7 or 5751, only the 5965 would really get the job done by today's standar .......
421: Tube DIY Asylum, RE: a bit more detail? (0.00)
Posted by Caucasian Blackplate on 2019-01-24, 10:41:21 (67.182.129.135)
Some of the parts values are still being tweaked to get exactly what I'm looking for. There's an EF-86 driving paralleled 12GN7 cathode followers which are directly coupled to the 810 output. There is .......
422: Amp/Preamp Asylum, RE: Hashimoto hm-7 SUT (0.00)
Posted by Caucasian Blackplate on 2019-01-24, 08:53:38 (67.182.129.135)
A scope and a test record. I didn't make pretty graphs. .......
423: Tube DIY Asylum, RE: 304TL (0.00)
Posted by Caucasian Blackplate on 2019-01-24, 08:34:37 (67.182.129.135)
That's a lot of effort for 20W! .......
424: Tube DIY Asylum, RE: 304TL (0.00)
Posted by Caucasian Blackplate on 2019-01-24, 07:18:49 (67.182.129.135)
Are you going to eek out the power you need in A1, or are you going to have to support A2? I just finished a pair of these. I aimed for lower voltage and very high plate current to keep things san .......
425: Amp/Preamp Asylum, RE: Hashimoto hm-7 SUT (0.00)
Posted by Caucasian Blackplate on 2019-01-23, 13:18:07 (67.182.129.135)
You can have your doubts. The response in my setup had a peak of a few dB around 13kHz, the small cap flattened it out, though I am down a little more up around 20kHz than I was without the cap. I hav .......
426: Amp/Preamp Asylum, RE: Hana Low Output (0.00)
Posted by Caucasian Blackplate on 2019-01-23, 08:42:48 (67.182.129.135)
Hopefully it's not 0.05, that's very low! At 0.5mV, you'll want a step-up transformer between your cartridge and the phono preamp. .......
427: Amp/Preamp Asylum, RE: Hashimoto hm-7 SUT (0.00)
Posted by Caucasian Blackplate on 2019-01-23, 08:36:03 (67.182.129.135)
Across the primary of the SUT. .......
428: Amp/Preamp Asylum, RE: LM 1875T . . . (0.00)
Posted by Caucasian Blackplate on 2019-01-22, 19:33:12 (67.182.129.135)
The datasheet shows 32ish watts into 8 Ohms with the max power supply voltage. This is a very, very hard clipping device. THD at 35W under those conditions could be well over 50%. .......
429: Amp/Preamp Asylum, RE: Hashimoto hm-7 SUT (0.00)
Posted by Caucasian Blackplate on 2019-01-22, 19:27:00 (67.182.129.135)
That's a broad statement about MC carts not needing capacitive loading. They don't need a ton, but it can help flatten out the treble a bit. I know with my particular cartridge likes a little extra ca .......
430: Tubes Asylum, RE: in that case.........WOW !!! (0.00)
Posted by Caucasian Blackplate on 2019-01-22, 13:37:30 (67.182.129.135)
Well, you dropped the term "normal speaker", and there are some abnormal speakers that might make use of the 100W, but ultimately there's a joke in here somewhere about compensating for something... T .......
431: Tubes Asylum, RE: A simple, curious, ignorant amp question (0.00)
Posted by Caucasian Blackplate on 2019-01-22, 12:42:04 (67.182.129.135)
The short answer is yes, you can drive a normal speaker with 10W. .......
432: Amp/Preamp Asylum, RE: Hashimoto hm-7 SUT (0.00)
Posted by Caucasian Blackplate on 2019-01-22, 12:40:53 (67.182.129.135)
I'd be happy to put something like that together for you, but do keep in mind that you will need to know what kind of resistive/capacative loading your cartridge wants first. Just putting the step-up .......
433: Tube DIY Asylum, RE: This ought to do the trick...... (0.00)
Posted by Caucasian Blackplate on 2019-01-22, 07:51:10 (67.182.129.135)
I just copied and pasted it into the auto-link generator in this post... .......
434: Tube DIY Asylum, RE: This ought to do the trick...... (0.00)
Posted by Caucasian Blackplate on 2019-01-22, 06:48:15 (67.182.129.135)
I just copied and pasted the links, they all work... .......
435: Tube DIY Asylum, RE: This ought to do the trick...... (0.00)
Posted by Caucasian Blackplate on 2019-01-21, 19:50:04 (67.182.129.135)
What I do is to use these: https://www.ebay.com/itm/CZH-PCB-Board-Adapter-Circuit-For-CMC-4pin-5pin-6pin-7pin-8pin-9pin-Tube-Socket/192565967388?hash=item2cd5d37a1c:m:mIw5mKaNHcCraEoJl-LQX1g:rk:132:pf .......
436: High Efficiency Speaker Asylum, RE: 7591 Tubes for My Edgars..opinions/experience (0.00)
Posted by Caucasian Blackplate on 2019-01-19, 16:32:58 (67.182.129.135)
True, 22V is 2.7dB more than 16. 35W is 1dB more than 28W. These are very, very close. You would be challenged to build a driver stage that can drive the grid at -16V but not the grid at -22V. Both a .......
437: Tube DIY Asylum, RE: Brainstorming (0.00)
Posted by Caucasian Blackplate on 2019-01-19, 08:30:07 (67.182.129.135)
Tubelab over on DIY Audio has done something very similar, with a DSP controlling the output of a SMPS. I would suggest contacting him if you'd like to develop the idea. .......
438: High Efficiency Speaker Asylum, RE: 7591 Tubes for My Edgars..opinions/experience (0.00)
Posted by Caucasian Blackplate on 2019-01-17, 17:55:50 (67.182.129.135)
For the EL34, -22V of bias gives 35W in cathode bias PP. That is well within the ballpark of the 7591A. .......
439: Tubes Asylum, RE: Tube Rolling (0.00)
Posted by Caucasian Blackplate on 2019-01-17, 12:40:48 (67.182.129.135)
Most 300B SET amps are zero feedback, so the differences between tubes is quite audible. The VTL tiny triode amps undoubtedly use a bit of feedback to improve performance. Still, you can afford a LOT .......
440: Amp/Preamp Asylum, RE: RCA (Pulled) Stereo Tube Amp Thoughts? (0.00)
Posted by Caucasian Blackplate on 2019-01-17, 09:29:55 (67.182.129.135)
The amp is missing cathode bypass caps on the output stage and is running pentode finals with no feedback. This will result in terrible speaker damping (very bloated bass that follows the impedance cu .......
441: Amp/Preamp Asylum, RE: RCA (Pulled) Stereo Tube Amp Thoughts? (0.00)
Posted by Caucasian Blackplate on 2019-01-17, 09:24:47 (67.182.129.135)
I would not buy it based on who was purported to have worked on it. At best, it's just unfinished. .......
442: Amp/Preamp Asylum, RE: RCA (Pulled) Stereo Tube Amp Thoughts? (0.00)
Posted by Caucasian Blackplate on 2019-01-17, 08:06:06 (67.182.129.135)
The output transformers appear to be very different. For some old console amps, you could find multi-channel amps where one channel drove a woofer and the other channel drove the higher frequency driv .......
443: High Efficiency Speaker Asylum, RE: 7591 Tubes for My Edgars..opinions/experience (0.00)
Posted by Caucasian Blackplate on 2019-01-16, 11:59:29 (67.182.129.135)
Well, that will help avoid the issues of HF rolloff since it isn't a receiver or an integrated with a bunch of filters and tone controls. Still, the company is mentioning that the 7591 was used by all .......
444: Amp/Preamp Asylum, RE: All Hail DeKay! The Grail arrived at my house today (0.00)
Posted by Caucasian Blackplate on 2019-01-16, 10:37:17 (67.182.129.135)
Can you remove the cover and shoot a photo of the inside? .......
445: High Efficiency Speaker Asylum, RE: 7591 Tubes for My Edgars..opinions/experience (0.00)
Posted by Caucasian Blackplate on 2019-01-16, 10:36:17 (67.182.129.135)
What is the amp in question? The 7591 and 7868 were made for "small form factor" stereo receivers back in the day. These units were always pushing the envelope for maximum power output at all costs. .......
446: Amp/Preamp Asylum, RE: Behringer Passive Preamp (0.00)
Posted by Caucasian Blackplate on 2019-01-15, 11:39:53 (67.182.129.135)
What is the input impedance on your Kenwood power amp? What are your sources? It is quite possible that both choices aren't optimal. .......
447: SET Asylum, RE: Lamn ML 1 (0.00)
Posted by Caucasian Blackplate on 2019-01-14, 17:05:14 (67.182.129.135)
The manual isn't readily accessible online, can you post the instructions? .......
448: Tubes Asylum, RE: Bad eBay Listings (0.00)
Posted by Caucasian Blackplate on 2019-01-13, 10:33:33 (67.182.129.135)
Yes, same guy. .......
449: Tube DIY Asylum, RE: Pre amp kits (0.00)
Posted by Caucasian Blackplate on 2019-01-13, 10:32:03 (67.182.129.135)
Yes, the photo TK posted gives a general layout of where things go and the schematic (which it looks like you have) provides the map to connect it all together. .......
450: Amp/Preamp Asylum, RE: Aunt Corey's Pre-amp... (0.00)
Posted by Caucasian Blackplate on 2019-01-13, 10:16:39 (67.182.129.135)
There is no reason that a turntable with a phono preamp can't be used with a passive linestage. .......
451: Tube DIY Asylum, RE: Pre amp kits (0.00)
Posted by Caucasian Blackplate on 2019-01-13, 09:29:07 (67.182.129.135)
I've put a few random half finished Welborne kits together for folks since the company closed. Since TK found a photo of the PC board, I could recreate it for you. Plan to pay at least $100 just for a .......
452: Amp/Preamp Asylum, RE: Perhaps Viridian could chime in ... (0.00)
Posted by Caucasian Blackplate on 2019-01-12, 13:45:30 (67.182.129.135)
It does not have 9 op-amps. Technically it doesn't use an op-amp at all. .......
453: Amp/Preamp Asylum, RE: I guess what I mean by clean is ... (0.00)
Posted by Caucasian Blackplate on 2019-01-12, 13:25:41 (67.182.129.135)
You'll have to get specific in terms of what you mean by "things". In the Aunt Corey preamp, there are 9 semiconductors per channel. .......
454: Amp/Preamp Asylum, RE: I've had the Schitt passive for awhile now ... (0.00)
Posted by Caucasian Blackplate on 2019-01-12, 10:18:09 (67.182.129.135)
What do you mean by "cleaner"? To evaluate whether a passive is a good idea, a complete rundown of your source components and amplifier(s) (including active subwoofers) needs to be considered. ::: TOP .......
455: Amp/Preamp Asylum, RE: Well, what do you call the Pass passive? (nt) (0.00)
Posted by Caucasian Blackplate on 2019-01-12, 09:16:57 (67.182.129.135)
A unity gain active preamp. On the Pass webpage for the B1, he actually clearly states what a passive preamp is: "Routinely DIYers opt to make themselves a "passive preamp" - just an input selector a .......
456: Amp/Preamp Asylum, RE: Aunt Corey's Pre-amp... (0.00)
Posted by Caucasian Blackplate on 2019-01-12, 08:15:56 (67.182.129.135)
A buffered passive preamp isn't a passive preamp, it's just a preamp (sometimes referred to as a unity gain preamp). .......
457: Tube DIY Asylum, RE: Has anyone converted tube hifi eqipmentt to a guitar amp? (0.00)
Posted by Caucasian Blackplate on 2019-01-12, 08:12:34 (67.182.129.135)
Assuming these both work, and Eico HF-85 is worth $400 and a Dynaco ST-70 a fair bit more. If you hack them up to make them into guitar amps, you will end up making them almost worthless. I know becau .......
458: High Efficiency Speaker Asylum, RE: Recommendations for stand mount for 10wpc amp (0.00)
Posted by Caucasian Blackplate on 2019-01-11, 16:30:11 (67.182.129.135)
It's really tough to get what you're looking for in a monitor speaker. The Dynaco A25 might also be a good one to try out. I didn't know that about the De Capo, but it isn't all that surprising given .......
459: High Efficiency Speaker Asylum, RE: Recommendations for stand mount for 10wpc amp (0.00)
Posted by Caucasian Blackplate on 2019-01-11, 15:39:53 (67.182.129.135)
I would bet that you could find a pair of Reference 3A De Capo speakers. The Soliloquy SM-2A3s were also pretty nice, but very hard to find. As far as the Contrast speakers go, 95dB sensitivity, a 5. .......
460: Amp/Preamp Asylum, RE: Are there any decent bluetoot receivers/integrated? (0.00)
Posted by Caucasian Blackplate on 2019-01-11, 08:44:07 (67.182.129.135)
Consider looking at network enabled receivers. That may get you what you want without dealing with Bluetooth. .......
461: Tube DIY Asylum, RE: G2 regulation (0.00)
Posted by Caucasian Blackplate on 2019-01-11, 08:43:30 (67.182.129.135)
I have done something similar with 6550 finals and a 6AS7 doing regulator duty. .......
462: MagneQuest/Peerless Forum, RE: Parafeed Baby O (0.00)
Posted by Caucasian Blackplate on 2019-01-10, 18:24:31 (67.182.129.135)
Cool! I like the cork work mat too. Are you running these on an external PSU? .......
463: Amp/Preamp Asylum, RE: Buy used Ayre v5xe amp to solve distorted vocals? (0.00)
Posted by Caucasian Blackplate on 2019-01-10, 17:39:35 (67.182.129.135)
Can you borrow a different amp from a friend to test your hypothesis? .......
464: Amp/Preamp Asylum, RE: Are there any decent bluetoot receivers/integrated? (0.00)
Posted by Caucasian Blackplate on 2019-01-10, 17:33:19 (67.182.129.135)
Why do you have to do it wirelessly? Can you get a DAC dock for your phone or plug your computer into your system? The Bluetooth transmission will leave a nasty mark on sound quality. .......
465: Speaker Asylum, RE: entronic mark IV bookshelf speakers (0.00)
Posted by Caucasian Blackplate on 2019-01-10, 15:38:29 (67.182.129.135)
Do you have a link to the listing? Lots of small speakers take tons of power. Good luck powering the LS3/5A with a small amp. .......
466: Amp/Preamp Asylum, RE: Are there any decent bluetoot receivers/integrated? (0.00)
Posted by Caucasian Blackplate on 2019-01-10, 10:00:10 (67.182.129.135)
Why do you need bluetooth? .......
467: Tube DIY Asylum, RE: 2k hz whine/squeal (0.00)
Posted by Caucasian Blackplate on 2019-01-09, 09:43:18 (67.182.129.135)
Probably one that requires a ceramic cap or two to keep it quiet! .......
468: Tubes Asylum, RE: Hot tube in ARC VT200 (0.00)
Posted by Caucasian Blackplate on 2019-01-08, 16:25:14 (67.182.129.135)
Yeah, check the screen resistors! (be sure the value is what you are expecting as well) .......
469: Tubes Asylum, RE: Hot tube in ARC VT200 (0.00)
Posted by Caucasian Blackplate on 2019-01-08, 16:07:27 (67.182.129.135)
Have you moved that tube around to be sure it's the actual position in the amp and not the tube itself? That could just be top mica that's a little more transparent than the others. The only good way .......
470: Amp/Preamp Asylum, RE: Problems of Renewing Capacitors (0.00)
Posted by Caucasian Blackplate on 2019-01-07, 20:17:34 (67.182.129.135)
In this post, you wrote: "I have never asked ML Customer Service to provide me any contact info." Two posts earlier you wrote: "If possible, I would like to know what the original designer of No. 23. .......
471: Tubes Asylum, Bad eBay Listings (0.00)
Posted by Caucasian Blackplate on 2019-01-07, 19:53:17 (67.182.129.135)
If you want to see some bad listings, I feel like this guy has a monopoly on them! This one is particularly bothersome, since one tube is from 2003 and one is from 2011. Other fun things from just th .......
472: Amp/Preamp Asylum, RE: Problems of Renewing Capacitors (0.00)
Posted by Caucasian Blackplate on 2019-01-06, 09:01:24 (65.120.249.3)
I posted a picture of a current production ML amplifier with Nichicon caps. Older electrolytic caps can have a +/-20% tolerance. It is not the service center's job to provide you the contact info of t .......
473: Tubes Asylum, RE: Speaking of fake tubes anyone ever see this 2a3 (0.00)
Posted by Caucasian Blackplate on 2019-01-05, 12:39:36 (67.182.129.135)
I've had some 6AS7G tubes in the past with nearly identical printing (they were Russian of course). .......
474: Amp/Preamp Asylum, RE: Problems of Renewing Capacitors (0.00)
Posted by Caucasian Blackplate on 2019-01-05, 11:07:24 (67.182.129.135)
You're going to want to let the amp run for a few hundred hours before you judge the performance of the capacitors. There is absolutely nothing wrong with Nichicon capacitors, and I would take them ov .......
475: Tube DIY Asylum, RE: resistors again! (0.00)
Posted by Caucasian Blackplate on 2019-01-05, 11:00:15 (67.182.129.135)
Is this for a push-pull amp? What you describe sounds like a cathodyne. If so, Mills are overkill and potentially a bit difficult to fit where you need them to be. The Vishay PR-01, PR-02, and PR-03 .......
476: Tube DIY Asylum, RE: Block Diagram (0.00)
Posted by Caucasian Blackplate on 2019-01-03, 11:57:58 (67.182.129.135)
The 47K resistor is likely necessary to implement the feedback. I too am quite curious about the 180K resistor. .......
477: SET Asylum, RE: Mystery 300B? Amp Kit (0.00)
Posted by Caucasian Blackplate on 2019-01-03, 08:23:02 (67.182.129.135)
Can you provide the specs for the interstage transformer? .......
478: Tube DIY Asylum, RE: Miller Effect (0.00)
Posted by Caucasian Blackplate on 2019-01-03, 08:21:20 (67.182.129.135)
You'll have to change your moniker to "Pentode_Fifedom" if this ends up being the solution. .......
479: Tube DIY Asylum, RE: Sakuma-style GM-70 design - critiques please! (0.00)
Posted by Caucasian Blackplate on 2019-01-03, 08:19:34 (67.182.129.135)
Does your load line show much benefit to crossing into A2? If not, you could maintain the Sakuma approach but with a plate choke on the first GM70. While you would lose some gain, you've made the conc .......
480: Tubes Asylum, RE: ultimate fakers (0.00)
Posted by Caucasian Blackplate on 2019-01-03, 07:14:07 (67.182.129.135)
Oh yeah, there are JAN tubes that aren't US made. Here's a good example of a pair of 6922s that say "JAN" and "Made in USA" but are certainly imports. .......
481: Vinyl Asylum, RE: Best moving magnet cartridge to use with (0.00)
Posted by Caucasian Blackplate on 2019-01-02, 18:55:59 (67.182.129.135)
This is a very good suggestion. Since you (the OP) are in Seattle, I would suggest contacting Andy at the Needle Clinic in Issaquah to see if he has any laying around that he might want to sell. The .......
482: Tube DIY Asylum, RE: Miller Effect (0.00)
Posted by Caucasian Blackplate on 2019-01-02, 13:23:50 (67.182.129.135)
Pentodes that can (somewhat easily) give a gain of 30 when pentode wired: 6CL6 (a very good choice) 6EJ7 8077 (an even better choice) 12BY7 6686 8608 6EH5 The tradeoff when you use these tubes is that .......
483: Tube DIY Asylum, RE: Miller Effect (0.00)
Posted by Caucasian Blackplate on 2019-01-02, 12:37:41 (67.182.129.135)
Oh come on TK, "barely acceptable at 10kHz" is really just "that sweet vintage sound". Are you putting some feedback around the EF86? Going back to pentode? Different pots? .......
484: SET Asylum, RE: Mystery 300B? Amp Kit (0.00)
Posted by Caucasian Blackplate on 2019-01-02, 08:06:20 (67.182.129.135)
A 6C45PI being fed by an interstage transformer will want the 0D3 to keep the plate voltage reasonable. I think you could do just fine building up your own circuit from scratch. .......
485: SET Asylum, RE: Mystery 300B? Amp Kit (0.00)
Posted by Caucasian Blackplate on 2019-01-02, 07:29:33 (67.182.129.135)
This is a kit that has been for sale at VT4C.com, though they are currently closed while they move. .......
486: Tube DIY Asylum, RE: Something I never paid any attention to before (0.00)
Posted by Caucasian Blackplate on 2019-01-02, 07:17:52 (67.182.129.135)
There's no harm in trying. .......
487: Tubes Asylum, RE: ultimate fakers (0.00)
Posted by Caucasian Blackplate on 2019-01-01, 19:59:40 (67.182.129.135)
I posted the information about the PA amps in missile silos, it didn't take long to find. Since the seller is asking about the same price that you'd pay for a quad of new production KT88s, why bother .......
488: Tubes Asylum, RE: ultimate fakers (0.00)
Posted by Caucasian Blackplate on 2019-01-01, 18:39:35 (67.182.129.135)
"So let me get this straight. JJ bought the tooling, but did not buy the Tesla name" Correct. "To the best of my knowledge they were not allowed to use the Tesla name." Possible correct, but not impor .......
489: Tubes Asylum, RE: ultimate fakers (0.00)
Posted by Caucasian Blackplate on 2019-01-01, 17:51:46 (67.182.129.135)
I don't know how dishonest this is, especially since the picture you showed was on the actual auction listing. The seller never claimed they are US NOS, and he does specify that they are made in Czech .......
490: Tubes Asylum, RE: What is the primary impedance for SE OPT for 6ar6 (0.00)
Posted by Caucasian Blackplate on 2019-01-01, 17:17:26 (67.182.129.135)
That's probably about perfect for the RH style amp. .......
491: Speaker Asylum, RE: BIG room, 4 speakers?, dumb questions (0.00)
Posted by Caucasian Blackplate on 2019-01-01, 16:07:51 (67.182.129.135)
That seems a little overkill for a workshop system and a little silly for an inexpensive pair of speakers. They are also not specified to be happy at 2 ohms. Why not try something that's a little more .......
492: Tubes Asylum, RE: What is the primary impedance for SE OPT for 6ar6 (0.00)
Posted by Caucasian Blackplate on 2019-01-01, 16:03:51 (67.182.129.135)
The Tung Sol datasheet gives a 1K plate resistance for triode wiring, but that's at 200VP/90mA, and you're not going to get very far running it there. I would maybe run it at 300V/55mA and a 6-7K t .......
493: Speaker Asylum, RE: BIG room, 4 speakers?, dumb questions (0.00)
Posted by Caucasian Blackplate on 2019-01-01, 13:04:42 (67.182.129.135)
If the speakers are identical and the amplifier can tolerate low impedance loads, there's no need for a second amplifier. The CV XLS215 lists a characteristic impedance of 6 ohms, so consider looking .......
494: Tube DIY Asylum, RE: So! In essence the answer seems to be: (0.00)
Posted by Caucasian Blackplate on 2019-01-01, 10:24:29 (67.182.129.135)
If you take the first cap out, you'll lose a fair amount of the magnitude of negative DC voltage (it should drop to about -24V at the remainin cap), the AC current load placed on the bias portion of t .......
495: Tube DIY Asylum, PJ's Answer (0.00)
Posted by Caucasian Blackplate on 2019-01-01, 10:21:13 (67.182.129.135)
link .......
496: Tube DIY Asylum, RE: Because it's a sow's ear? (0.00)
Posted by Caucasian Blackplate on 2018-12-31, 15:57:00 (67.182.129.135)
No, it's more that you're fixing a problem that doesn't exist, and decreasing the resale value in the process. To try what Gary is suggesting, you would want four chokes and an appropriate place to us .......
497: Tube DIY Asylum, RE: I asked a similar question here, about 6 years ago (0.00)
Posted by Caucasian Blackplate on 2018-12-31, 15:46:06 (67.182.129.135)
Yes, I agree with Joe that regulating isn't necessarily such a good idea. Having said that, I could really care less if my line voltage jumps from 120V to 125V and the bias supply is slow to follow (s .......
498: Tube DIY Asylum, RE: Hammond 156C (0.00)
Posted by Caucasian Blackplate on 2018-12-31, 15:40:07 (67.182.129.135)
I wouldn't recommend actually doing that to an ST-70. .......
499: Tube DIY Asylum, RE: Fixed Bias supply (0.00)
Posted by Caucasian Blackplate on 2018-12-31, 14:21:13 (67.182.129.135)
Or just replace the 10K filter resistor with a tiny little choke, like a Hammond 156C. The 470uF cap should charge up fairly well in about 10 seconds, the EL34s will take a lot longer. .......
500: Tube DIY Asylum, RE: Fixed Bias supply (0.00)
Posted by Caucasian Blackplate on 2018-12-31, 13:21:18 (67.182.129.135)
Increasing the first cap after the rectifier will increase the initial load on the power transformer until it is charged (which is pretty quick). The rest of the amp isn't going to be doing a whole lo .......
Found total of 500 records, Query: , Author: Caucasian Blackplate in All Forums, Time: 2 sec.