Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: burt_toast on February 19, 2012, 03:41:19 pm

Title: plexi/pro bypass switch
Post by: burt_toast on February 19, 2012, 03:41:19 pm
hey fellas,

okay, i’m sure someone on this forum have tried this before, but...
on my plexified bandmaster, i’d like to try adding a switch that cuts out the cathode-follower, tone stack, and pre-PI MV all in one fell swoop.

my question is: when i have is it okay to leave everything that’s bypassed open (ungrounded)?  will it damage that tube?

in my attached drawing, you’ll also see another 3-pole version of the switch, that does ground the V2 grid when bypassed, i just don’t have one of those switches on hand.

i’d love the flexibility of having the plexi-ish MV thing, and a simpler, Fender Pro-ish thing.

what do you think?
Title: Re: plexi/pro bypass switch
Post by: PRR on February 19, 2012, 09:40:24 pm
It won't burn-up, but will mis-bias when bypassed and POP when re-engaged. Would be better to keep V2 grid grounded.
Title: Re: plexi/pro bypass switch
Post by: burt_toast on February 20, 2012, 05:41:45 am
thnks PRR!
yeah, i was thinking that grounding v2 grid would be better, just couldn't with the way i had it drawn.
brilliant! can't wait to try it
scott
Title: Re: plexi/pro bypass switch
Post by: burt_toast on February 24, 2012, 11:27:00 am
wow, works like a charm! should've done this years ago. it's cool to have a purer sounding non-mv alternative. very nice in my cathode-biased el34 bandmaster 2x12 combo.
highly recommend this mod, thanks again, PRR
scott