JMP master volume mod...

[dcline]

I'm working on a 76 JMP 50 watt master volume model.
Someone has modded it with the post PI, dual pot master volume.
I always thought these amps sounded great with the stock pre PI master volume. I have yet to put new tubes in it to come to a conclusion. Sounds pretty buzzy right now.
Just wanted to get some feedback as to why someone would mod one of these amps like this? Need to tell the owner something. Not sure if I should leave it or put it back to stock...
He says the "presents" does not work either. And I have to agree with him that it seems to do nothing. Mind you the tubes are very old. Just wondering if this mod would effect the presents control?

[Reeltarded]

Yes it kills the NFB circuit, and there goes the presence.

I have 3 masters on a couple amps. The PPIMV knocks off about the upper 20%, and the others stage however to make the difference.

Leave it and use less. I set mine at around 70-80 percent. I like being able to dial in rudeness with it.

[dcline]

Interesting... Thank you!