Tube amp signal path switches: What ratings to use?

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Donkey
Posts: 11
Joined: Fri Dec 06, 2019 11:00 am

Tube amp signal path switches: What ratings to use?

Post by Donkey »

Greetings fellow tube heads! I was hoping for some clarification for safety's sake. I was looking to add a bright switch to an amp. Looking around the schematic I see the caps are rated for 630v and the only switch I see in the signal chain is a rotary switch rated for 1A, but no voltage listed. None of the pots show a voltage/ampacity rating. What switch would be safe to use in the instance? Looking at other amp designs I have seen your typical small push button or mini toggle used. Do I need to be using a switched rated for 630v/ 1A? Thank you in advance!
pdf64
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Re: Tube amp signal path switches: What ratings to use?

Post by pdf64 »

There are no safety issues with such switches, as a preamp signal couldn’t cause injury.
For signal switches in a preamp, voltages can’t really exceed 100Vac, and current levels will be a few mA. So pretty much any robust switch will work ok. Insufficient wetting current is a potential issue if something really beefy is used.
Consider that if switches rated for voltages over 250V were readily (and cheaply) available, then they would be used for those nonsensical standby switches.
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Donkey
Posts: 11
Joined: Fri Dec 06, 2019 11:00 am

Re: Tube amp signal path switches: What ratings to use?

Post by Donkey »

pdf64 wrote: Sun Nov 15, 2020 2:52 pm There are no safety issues with such switches, as a preamp signal couldn’t cause injury.
For signal switches in a preamp, voltages can’t really exceed 100Vac, and current levels will be a few mA. So pretty much any robust switch will work ok. Insufficient wetting current is a potential issue if something really beefy is used.
Consider that if switches rated for voltages over 250V were readily (and cheaply) available, then they would be used for those nonsensical standby switches.
Thank you sir!
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