Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dunner84 on July 26, 2022, 02:45:09 pm

Title: Preamp signal path switching
Post by: dunner84 on July 26, 2022, 02:45:09 pm

Hello,

I am thinking about building a Matchless Clubman inspired preamp, and I thought it would be nice to include a switching scheme to go from stock, ef96 only(bypass parallel 12ax7), parallel 12ax7 only (no ef86).

Any ideas or slick ways of implementing this?

Title: Re: Preamp signal path switching
Post by: tubeswell on July 26, 2022, 05:04:31 pm

You need relays or optocouplers


Look at SLO100 pre-amp, or even the humble PV Classic 30 to see how to set up channel switching for overdrive

Title: Re: Preamp signal path switching
Post by: shooter on July 26, 2022, 06:54:33 pm

u could plex it and just blend

Title: Re: Preamp signal path switching
Post by: jordan86 on July 30, 2022, 08:48:08 am

Doesn’t someone have a parallel/series switch design? Maybe sluckey? If you did two inputs, one for each preamp tube, you could have the isolated inputs plus the “stock” series arrangement?

Title: Re: Preamp signal path switching
Post by: CascoSieg on August 04, 2022, 03:55:22 pm

Here are two examples I've done, though I think the OP just asked about an "either or" switch. The "either or both" example uses the switch layout from one of Sluckey's builds, which gives you one input path OR the other input path OR both paths together...  and the other "either or both or cascaded" I worked out as a mod to a 5F6A based build, which also allows for cascading one input path into the other, which might allow the original Clubman circuit to also be in place.