Preamp MV versus PPI MV

[orca]

I want to rebuild my ALLEN Old Flame with a Dumble like preamp.The
ALLEN has a PPI mastervolume; I think about changing it to a preamp
mastervolume like the Dumble amps.
Pros and Cons by the experienced builders are very appreciated.

[drz400]

I want to rebuild my ALLEN Old Flame with a Dumble like preamp.The
ALLEN has a PPI mastervolume; I think about changing it to a preamp
mastervolume like the Dumble amps.
Pros and Cons by the experienced builders are very appreciated.

Post Phase masters get very ratty as you get to lower levels but allow you to hit the phase inverter harder so they work better on amps with very little preamp gain. It really wouldn't work well with a Dumble circuit

[Bob-I]

IMHO PI's distorting sound like ass. I'd rather use a well thought out preamp OD. Power tube distortion comes in up high on the list also.

[Wayne]

Caution - newb question follows:

Since a PI is push-pull stage, shouldn't it be possible to design a PI that has similar distortion characteristics to a PP power stage, but "smaller"? I'm thinking maybe using tubes that can take a bit of grid current, and maybe pentodes as opposed to triodes. Not sure what else would have to change from the classic LTP we all know and (?) love.

Any thoughts/past experiences, anyone?

W

[Jackie Treehorn]

I've got a post phase inverter master in my Dumble style amp. It's the dual 1 meg pot style. I'm pretty happy with it. The amp has the usual lead master but no clean master. It sounds better to me than just using the conventional style master. You get another layer of harmonics. The phase inverter is not in a global feedback loop, though and the PI has dual 100k plates. You may want to give it a shot.

[phsyconoodler]

There are a couple of ways to do a PPIMV so don't write if off as 'sounding like ass' just yet.
I find the Allen master volume to be awful sounding.I recently installed a type 1 PPIMV on a Deluxe Reverb and it was glorious sounding,especially at low volumes.
BTW,I like the dumble master just the way it is.

[orca]

thanks,Psychonoodler,
the ALLEN PPIMV I have in my OLD FLAME is the same as the
"Master Volume Type 1 by Trainwreck Circuits.
I will try a 500K or 250K pot as an alternative.
What about a Dumble style preamp MV plus the PPIMV I have?