I think there's some misunderstanding

Posted by Tre' (P) on January 26, 2017 at 08:45:06

In Reply to: Russian K-40 -voltage rating for Bottlehead Amp posted by Dingojazz on January 25, 2017 at 18:29:17:

I believe when Paul said "The voltage in the SEX amp is around 400v..." he meant that the supply voltage is around 400v under operating condition.

That's not the same as saying that the voltage at the coupling cap is 400v under operating condition.

When the amp is first turned on the tubes are cold and not ready to draw current.

Until the tubes are warmed up and start to draw current the full supply voltage will be "everywhere".

Once the tubes are warmed up and the circuit reaches operating condition the voltage at the coupling cap will be lower than the supply voltage (by the amount of voltage drop across the plate load) but still the cap needs to be able to take the full supply voltage, at least for a short time, each time the unit is turned on cold.

So all the caps in a circuit need to be rated at the full supply voltage (plus a little more ie "a bit higher at startup for a few seconds") for safety and longevity.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

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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

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

I think there's some misunderstanding

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