anyone got a Marshall plexi pre PI master to recommend?

[dstroud]

Wasn't someone here liking the pre PI master's in plexi's? I'm not too happy with the way my PPIMV is working in my plexi, it usually ends up dimed and attenuated. I was going to try a pre PI mv just to see what it's like - anybody got a good one the recommend?

 

[Nigel Tufnel]

Just copy the one from a jcm800. It's a 1m audio wired as a voltage divider between the tonestack output and the pi input. The only drawback is that you will always be dumping some signal to ground even if the master is dimed. It is possible to switch it in and out of the circuit with a common switch that you can probably pick up at your local Radio Shack, at least the one near by me carries one that will work. It's not a bad master by any means but if you like using every bit of gain that your plexi has then it may not fly for you, it also needs to be turned up a decent amount before the amp can breathe, but you don't get the fizzy's nearly as bad as the ppimv at low volumes.

 

[Anonymous]

go to ampgarage.com amd search for VVR.

 

[dstroud]

Just copy the one from a jcm800. It's a 1m audio wired as a voltage divider between the tonestack output and the pi input. The only drawback is that you will always be dumping some signal to ground even if the master is dimed. It is possible to switch it in and out of the circuit with a common switch that you can probably pick up at your local Radio Shack, at least the one near by me carries one that will work. It's not a bad master by any means but if you like using every bit of gain that your plexi has then it may not fly for you, it also needs to be turned up a decent amount before the amp can breathe, but you don't get the fizzy's nearly as bad as the ppimv at low volumes.

Cool, that looks simple, I'll probably try that 1st.

 

[dstroud]

Post Phase Inverter master Volumes suck tone at less than fully dimed settings. It reacts with the Phase inverters coupling caps rolling off bass as you turn it down. The whole idea for a PPMV is to be able to cause the PI to drive into distortion, which on many amps does not sound good, it was more for the vintage amp to get a little more hair. Pre Phase inverter master volumes do not suck tone as much or if at all. They limit the amount of drive to the PI. Amps that sound good at lower volumes that have master volumes are almost always of the Pre Phase inverter types. Hi Gain or modern amps are much better sounding with pre Phase inverter master volumes.

Yeah, I'm experiencing what you've described - I'll just kick in a bit of gain from my TS to make up the difference until I get to play arena's and then just dime my plexi !

 

[dstroud]

go to ampgarage.com amd search for VVR.

Thanks, that looks like a definite possiblity - I just emailed the guy for price and info.