6g3 Master Volume conundrum

[luthierwnc]

Hi again.  Sorry to be a pest.
I'm on the drawing board for a 6G3 build and was wondering about a master volume.  As a rule I'm not a MV guy for low-powered amps but this might be a home rig too.  That bias wobble seems making a PPIMV problematic.  I was wondering if the Mission style with a dual-gang pot feeding another set of coupling caps before the bias insertion point is the way to go.  I'm adding a graphic I stole from another thread here.  I've used the two-cap design several times and like it but don't want to mess-up the tremolo.  Thanks as always, Skip

[d95err]

I think the PPIMV and bias wiggle tremolo should work without the additional caps. At least, I vaguely recall seeing gut shots of some boutique amp that had that.

Haven’t tried it myself though.

[luthierwnc]

I'm not more than half sure I even want one, but I'm in the real estate portion of layout and that will take another inch on the board.  Thanks for your thoughts, sh

[pdf64]

A type 3 MV can be added without any downsides or board space really, though a couple of 4k7 - 10k resistors help them to work much nicer.

[reggiepe]

Try this one.....it has worked on 3 of my 6G3 builds so far. The Down Brownie uses this MV as well.

[pdf64]

Try this one.....it has worked on 3 of my 6G3 builds so far. The Down Brownie uses this MV as well.

That will put the 500k pot track across the 220k grid leak, which will lose a few dB of gain and max output voltage when set to max.
Not a big deal, but that can be avoided by using a 250k pot and 2M2grid leaks, the latters’ only purpose being as a safety backup, to maintain bias if the pot failed.

[luthierwnc]

Thanks gents.  PDF64; that's how I've always done mine -- but never tried it with a bias trem.  For some reason I thought that would attenuate the tremolo signal along with the gain.  Cheers, sh

[ac427v]

I used the Collins version in mine and it works great and no effect on the trem. I used .2uf value for the caps connected to the pi plate resistors and .1uf for the second set.

[pdf64]

Thanks gents.  PDF64; that's how I've always done mine -- but never tried it with a bias trem.  For some reason I thought that would attenuate the tremolo signal along with the gain.  Cheers, sh

I can’t see that any type of madter vol could affect the trem, sorry that I overlooked that query in post #1 

[d95err]

I vaguely recall seeing gut shots of some boutique amp that had that.

Now I remembered... take a look at Cutthroat Audio's Down Brownie amp. It's a 6G3 with PPIMV. They have some fairly detailed gut shots on their web site, so you can see how they implement the PPIMV. As far as I can see, it's a dual pot PPIMV, where the pot replaces the bias resistors.

https://cutthroataudio.com/product/down-brownie/

[tubeswell]

If you are perplexed by which MV to use, then allow me to complicate things further by suggesting another way of approaching overall volume reduction. Look at the power attenuator switches on Fender 'EC' series Vibrochamp, Tremolux and Twinolux. YMMV

[luthierwnc]

Thanks again,

D95err; I've blown that up.  Great resolution!  It looks like a fairly conventional Fender adjustable fixed bias too. 

I always have to be careful not to add too many gimmicks.  Whenever I decide I want to make a versatile little amp with some distortion, I always wish it was louder and cleaner.  I've got pedals to make it sound different.  That adjustable NFB is intriguing.  I've done that with a pot before but that was for smaller adjustments on a blackface.  For the power transformer I'll get an Allen 310-0-310.  It's beefier than called-for but I couldn't make a standard 330-0-330 deluxe trannie get the right volts on the Duncan PSU app without a 5Y3 or 5V4 rectifier tube. 

Cheers to all and I appreciate your interest.  Skip
Tubeswell; interesting!  Need to do a bit more research for a future build but I wasn't expecting that.  sh