Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Sonny ReVerb on September 11, 2025, 07:59:41 pm

Title: Switching cap across plate resistor
Post by: Sonny ReVerb on September 11, 2025, 07:59:41 pm

I'm considering a single channel Vibrolux 6g11a (https://el34world.com/charts/Schematics/files/Fender/Fender_vibrolux_6g11a.gif). I'd like to put the bright cap and the 'dull' cap on a DPDT switch to alternate between a Bright and a Normal channel. The Bright position would add the bright cap and remove the dull cap and vice-versa for the Normal position. I've often done a bright switch across a volume pot, but I haven't tried a cap with a switch across a plate resistor. Would this require a de-pop resistor or something?

Title: Re: Switching cap across plate resistor
Post by: Merlin on September 12, 2025, 04:27:08 am

You might get away without a de-pop resistor but why not include it anyway? I would recommend switching the cap to ground rather than across the plate resistor (amp response is the same either way), so there is no need for high voltage DC on the switch.

Title: Re: Switching cap across plate resistor
Post by: Sonny ReVerb on September 12, 2025, 06:58:43 am

I'll give that a try. Thanks for the help!