dumb question and a bad idea but...

[stevesamps]

Can you break the circuit at the last .02 cap in a 5e3 and install a "pre
PI master volume or would that just not work at all?
in other words between the driver and the inverter..
run that .02 up to 1 meg or 500k pot
and then back down to the grid of the inverter..
I have a customer who insists on master volume all the time
this is not a real 5e3 just a bogen thing I converted..
its actually a cool little amp with a 6au6 preamp
5e3 phase inverted driver and 6aq5 outputs
a K10 I have not had it on very loud but it should be interesting

[MWJB]

My gut feeling is that a pot hooked up as you describe won't actually work very well as a master volume. I did a bit of tweaking with different values here and the degree of attenuation with values of less than 1 meg is not as marked as you might think. You might also have greater risk of instability/oscillation due to the longer grid wire running to the pot & back.

A simpler idea might be to replace the 2x220K resistors grounded from the power tubes grids, with a dual ganged 250K pot wired as a variable resistor? Mount as close to original components as possible.

[petemoore]

A simpler idea might be to replace the 2x220K resistors grounded from the power tubes grids, with a dual ganged 250K pot wired as a variable resistor? Mount as close to original components as possible.
I wired a 500k pot, but with a switch on the wiper, leaving the two 220k's as stop R's in case the pot. I had room to do this using ~1.5'' wires.
I'm not sure what having 500k between the grids 'does' [when I lift the wiper connection that's what I have], sounds great, I didn't *notice a difference before/after the mod with the wiper lifted. I'm using this amp mostly with SP through one tube at a time, a very nice feature.

[stevesamps]

so far this little 10 watt amp should not need a master its kinda cool
having the 5e3 sound scaled down with the 6aq5's to 10 watts
Right now I have way too much gain because of the pentode up front
thanks for the idea I wanted to try that post PI thing with cathode bias
anyway maybe I can talk this guy out of the master idea based on the already cool low powered amp it is..