Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dwinstonwood on May 07, 2022, 02:44:02 pm

Title: Tone stack & NFB switch
Post by: dwinstonwood on May 07, 2022, 02:44:02 pm

I'm thinking about a single SPST switch that would cause a pretty big change in my current amp project.

Is an AB763 type tone stack bypass simply a switch that lifts the Mid pot's ground connection?

I would like to combine this with breaking the NFB connection to the speaker terminal, both with the flip of a single On/Off switch.

Any reason this wouldn't work?

Thanks!

Title: Re: Tone stack & NFB switch
Post by: sluckey on May 07, 2022, 03:25:54 pm

Quote from: dwinstonwood on May 07, 2022, 02:44:02 pm

I'm thinking about a single SPST switch that would cause a pretty big change in my current amp project.

Is an AB763 type tone stack bypass simply a switch that lifts the Mid pot's ground connection?

I would like to combine this with breaking the NFB connection to the speaker terminal, both with the flip of a single On/Off switch.

Any reason this wouldn't work?

Yes. You need a DPST switch.

Title: Re: Tone stack & NFB switch
Post by: dwinstonwood on May 07, 2022, 04:21:30 pm

Thanks! Of course, that makes sense now that you say it!

It's two separate circuits I'm breaking that can't be shorted together on a SPST.  :BangHead:

Title: Re: Tone stack & NFB switch
Post by: dwinstonwood on May 08, 2022, 10:38:57 am

I don't want to run speaker jack wires back and forth across the chassis to this front-mounted switch. So, I'll try this setup and see what I think. It's easy to disconnect if it turns out to be a bad idea. And, I can always add a second switch on the back of the chassis next to the speaker jack to disconnect the NFB.

"ON" = tone stack and bright cap
"OFF" = tone stack bypassed and no bright cap