I bought a pair of the tent labs filament supplies for my 300B/ D3a SE amp. And I just wanted to say worth every penny. I have high efficiency speakers and there is not a lick of noise. None Worked perfect. I wouldn't do an amp without them after the results I got on this.
Another thing I was quite happy with is those Soviet Paper in Oil caps for sale on ebay
VINTAGE RUSSIAN PAPER IN OIL - PIO - CAPACITOR - 8uF 400V - MATCHED PAIR - NEW | eBay
I have a pair of these and a pair of 100uf. They are huge but they measured spot on and my power supply is quiet and dynamic. I will say one things though they pack a serious punch if you forget to discharge them and stick your hand in there!.. Zapped myself with 500v 3 times. ( I know I am slow learner)
Just wanted to throw this out there in case anyone had seen these and was on the fence about it.
Another thing I was quite happy with is those Soviet Paper in Oil caps for sale on ebay
VINTAGE RUSSIAN PAPER IN OIL - PIO - CAPACITOR - 8uF 400V - MATCHED PAIR - NEW | eBay
I have a pair of these and a pair of 100uf. They are huge but they measured spot on and my power supply is quiet and dynamic. I will say one things though they pack a serious punch if you forget to discharge them and stick your hand in there!.. Zapped myself with 500v 3 times. ( I know I am slow learner)
Just wanted to throw this out there in case anyone had seen these and was on the fence about it.
Safety First!
You should use Bleeder Resistors.
Calculate the RC time constant of the bleeder resistor x the total capacitance.
Example, 200uF and 50k Ohms has a time constant of 10 seconds.
500V squared/50k Ohms = 5 Watts.
Use at least a 20 Watt resistor (a burned out bleeder resistor never saved anybody).
Use a resistance that will make the voltage safe by the time you un-screw the bottom cover off the amplifier.
500V becomes 185V in the first time constant.
185V becomes 68.5V in the next time constant.
68.5V becomes 25.3V in the next time constant.
A time constant of 10 seconds, and 25 seconds before removing the cover gets you safely to 1st base.
40V is the maximum voltage for exposed test equipment connections (safety standard).
Always work on electronics with Dry Hands.
Prevent the "Surviving Spouse Syndrome".
You should use Bleeder Resistors.
Calculate the RC time constant of the bleeder resistor x the total capacitance.
Example, 200uF and 50k Ohms has a time constant of 10 seconds.
500V squared/50k Ohms = 5 Watts.
Use at least a 20 Watt resistor (a burned out bleeder resistor never saved anybody).
Use a resistance that will make the voltage safe by the time you un-screw the bottom cover off the amplifier.
500V becomes 185V in the first time constant.
185V becomes 68.5V in the next time constant.
68.5V becomes 25.3V in the next time constant.
A time constant of 10 seconds, and 25 seconds before removing the cover gets you safely to 1st base.
40V is the maximum voltage for exposed test equipment connections (safety standard).
Always work on electronics with Dry Hands.
Prevent the "Surviving Spouse Syndrome".
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At which stage of the power supply do you use the big Russian caps? Is the 400V rating a concern? You mention you had them at 500V. Thx.
Good question.
If the rectifier warms up before the output tubes, the whole string of chokes, caps, and series resistors might all be at 500V.
Or, if the output tube(s) die, there might be 500V on all caps.
If the rectifier warms up before the output tubes, the whole string of chokes, caps, and series resistors might all be at 500V.
Or, if the output tube(s) die, there might be 500V on all caps.
Also bleeder resistors go on FIRST. I made the mistake of "I'll do that later" and not even 5 minutes later I zapped the **** out of me.
If need to add bleeders then you can put 2 caps in series for 4 uF and make a series of 2 bleeder resistors that divide the voltage exactly in half.
This way you take 2 pigeons with on shot. But some good design of the power supply with a good simulator would be a good thing to do first. If not available you could ask someone who can do it for you.
This way you take 2 pigeons with on shot. But some good design of the power supply with a good simulator would be a good thing to do first. If not available you could ask someone who can do it for you.
Attachments
My B+ is 400 When I got zapped off the 500v it was with no load. It runs at 400V. I have a 100uf that I believe is rated 400V also. These are the russian equivalent of mil-spec. I am hoping they are over rated a bit. So far they have worked great. I am thinking there is a fair difference between stereo use a few hours a week vs 24/7 usage. Time will tell I suppose. So far though I have been pleased.
If you are using RC coupling from the driver to the output stage, be sure to use 600V or 630V rated coupling caps.
It does depend on your circuit topology.
But in many cases . . .
If the B+ ever goes to 500V, that is a no no for a 400V coupling cap.
It does depend on your circuit topology.
But in many cases . . .
If the B+ ever goes to 500V, that is a no no for a 400V coupling cap.
My coupling caps are Duelend cast copper and are 600v. These are PS caps going to ground from B+. They may not last as long as they otherwise would but they don't get warm and have worked for 2 years so far. And I love the sound of this amp. hesitant to change it.
500V DC is a whole other world of getting zapped from 120v ac. Once I had it actually blow a hole in my arm and I bled all over the place from being shocked. Must have been a tiny steam explosion. I can still remember exactly how it felt all three times I got hit with that much. I am lucky it didn't kill me. Once was from one hand to the other but it didn't do anything but hurt. Not recommending it btw... But damn..... that hurt on a whole other level from a mains zapping. 120 vac seems quite benign now. ( yes i know it isn't)