RE: Thanks Dr., for responding.... - That quote

Posted by tube wrangler (M) on January 26, 2017 at 20:19:57

In Reply to: RE: Thanks Dr., for responding.... - That quote posted by Triode_Kingdom on January 25, 2017 at 20:59:59:

I agree. If your power supply settles at 400VDC, then get a 730VDC cap, or better.

Running the ratings game is just silly. You can get caps over 1200V. What, then, is the reason for using a 400V cap on a supply that settles at 400V. Excursions during startup can go over 600V-- or more if a tube doesn't wake up on time....

Spikes during forced clipping aren't very pretty, either, and many caps DO fail anyway-- even at LOWER than rated VDC.

I routinely overdrive completed amps with reputable caps that are rated
at least 35%, or more, over spike levels during startup and tube failure.

So far, all of these have lived. Don't ever expect 100%, though....

Occasionally, I see even these fail on initial testing and break-in. Why do they do that? Anything that man makes varies. There are no two equally rated and tested caps by any manufacturer that even resemble each other.
They're just like cars-- buy two of the exact same model, drive both the same way-- one runs 150,000 miles, the other one runs 360,000 miles. Maybe a third one cracks-up at 65,000 miles. Same car, same driving.

People who get one of those third ones often fantasize that all they need is a different brand. Not so! Buying another of the SAME brand ups the odds of the second one lasting much longer.

After all, man has never built two things exactly the same-- ever.

Run your caps at least 45% over rating, unless you know exactly how the materials behave under actual use conditions.....

Sometimes you can run close-to-rating. You can even get away with it if
you know everything that's happening in the circuit and everything about the part's materials and construction.

OR-- you might just get Lucky-- some do once in a while--! Personally, I don't enjoy using things that were built on Luck.....

---Dennis---

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Follow Ups Full Thread

Topic - Russian K-40 -voltage rating for Bottlehead Amp - Dingojazz 18:29:17 01/25/17 (15)

Thanks everyone, for all - Dingojazz 14:03:48 01/26/17 (0)

Forget the response I posted to you earlier. - Michael Samra 13:55:54 01/26/17 (0)

RE: Russian K-40 -voltage rating for Bottlehead Amp - Paul Joppa 13:46:16 01/26/17 (0)

RE: Russian K-40 -voltage rating for Bottlehead Amp - krankkall 09:40:37 01/26/17 (0)

I think there's some misunderstanding - Tre' 08:45:06 01/26/17 (0)

You will be fine. - Michael Samra 05:20:20 01/26/17 (1)

RE: You will be fine. - drlowmu 08:23:02 01/26/17 (0)

RE: Russian K-40 -voltage rating for Bottlehead Amp - xaudiomanx 05:07:40 01/26/17 (0)

RE: Russian K-40 -voltage rating for Bottlehead Amp - sser2 00:24:23 01/26/17 (1)

RE: Russian K-40 -voltage rating for Bottlehead Amp - sony6060 04:04:42 01/26/17 (0)

Its a function of WHERE the cap is, in the circuit. - drlowmu 19:19:58 01/25/17 (4)

Thanks Dr., for responding.... - That quote - Dingojazz 20:41:13 01/25/17 (3)

RE: Thanks Dr., for responding.... - That quote - Triode_Kingdom 20:59:59 01/25/17 (2)

RE: Thanks Dr., for responding.... - That quote - tube wrangler 20:19:57 01/26/17 (0)

RE: Thanks Dr., for responding.... - That quote - Michael Samra 05:23:54 01/26/17 (0)

Follow Ups

RE: Thanks Dr., for responding.... - That quote - tube wrangler 20:19:57 01/26/17 (0)

RE: Thanks Dr., for responding.... - That quote

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