4 input Marshall master volume options...

[FNM]

Anyone have experience with the different options for a master volume on a four input Marshall?

I'm definitely gonna do this, but am not sure if I should go with the one which has a 1 meg pot between the treble pot output and the coupling cap going to the first triode of the phase inverter, or the PPIMV which has a dual 1 meg pot right after both the phase inverter coupling caps to the output tubes.

Anyone ever tried both? Any input?

[HeavyHand]

have you tried the message board over at metroamp.com? they'll be all over it. this stuff is basically all they talk about. other than that i cant help at all. good luck man.

[nclayton]

If you want more gain and nastiness before the master volume then by all means do the post phase inverter master. One problem though is that the master volume is inside the feedback loop. That means when you turn the master volume down you lose tons of negative feedback. Your instinct might be that that's a good thing since NFB is evil or whatever, but you've got a class AB amp, and if it's not biased real hot then you might get a cruddy crossover region and a gritty sound. Also as you turn the MV down the presence control will stop working. By the time it gets down to around 9 or 10 o'clock the presence control will be basically useless.

Personally I like the more traditional post-tone-control-pre-phase-inverter master. Less overall distortion but much nicer sound.

Ned

[HeavyHand]

go to the metroamp forum and ask for the lar/mar PPMV. it is widely regarded as one of the better master volume designs.

[FNM]

I went ahead and tried the pre phase inverter one since it's so simple and it's pretty cool. I think the main thing that sounds killer about those amps is the output tubes distortion, so I don't know if I'll be better off if I do a different type of MV, but I'm pretty happy as it is.

Checked out the metro amp forum too and looks like I'll be busy there for a few days.

Thanks