Lar Mar PPIMV in princeton reverb AA1164

[J&F]

I'm restoring /rebuilding a AA1164 princeton reverb (5uag)
is it possible to install a post PI master volume like the Lar Mar type ?
(see my schem, the 250pot is dual gange)
is it safe and do I need to put 470 screen resistors (pin 4) and /or 1.5k resistors (pin 5)
because of this mod

thanks for your help masters

[Chuck H]

I would suggest screen resistors and grid stoppers in any amp no matter about vintage or application. The PPMV changes very little about the need for these components with a nod to fact that layout is critical and extra lead length can contribute to instability. Grid stoppers can help stabilize an amp. If your interested in keeping the circuit as original then you'll need to omit the PPMV. So why not play it safe and use the screen R's and grid stoppers as well?

[J&F]

overseas thanks chuck!!

[imaradiostar]

I don't think I'd bother with a PPIMV in a cathodyne phase inverter amp. The general consensus seems to be that the phase inverter doesn't distort in a pleasing way. Of course- that's just my reasoning. You may feel differently about it.

A PPIMV seems to sound better in an amp with a long tailed phase inverter. See the Orange tiny terror for a practical example.

jamie

[J&F]

yes, maybe a weber minimass is better to crunch at home

[Chuck H]

Affordable and effective:

http://music-electronics-forum.com/t23924/

I even built one on an aluminum plate that I form bent by clamping it between two boards. The plate was formed to mount on the back of a 20W combo amp (screwed into the BACK of the rear panels, so no visable holes). Sorry, no pics and the amp is with it's new owner.