Lar/Mar PPI-MV question

[jackplug1]

Will this work for cathode bias?
Which works best, Audio or Linear taper?

[sluckey]

Will this work for cathode bias?   yes
Which works best, Audio or Linear taper?   your choice

This circuit can be simplified. Search some more.

[jackplug1]

Will this work for cathode bias?   yes
Which works best, Audio or Linear taper?   your choice

This circuit can be simplified. Search some more.

Do you mean this?:

[pdf64]

Yes, that should work fine 

If the application is to get overdrive at domestic friendly SPLs, then an audio taper pot would be best.
Whereas if you're just a tiny bit too loud for your band and being able to turn it down a touch would be handy, then a linear taper may be better. But it would be a hair trigger between 0-1 to get domestic SPLs with a linear pot.

[jackplug1]

Yes, that should work fine 

If the application is to get overdrive at domestic friendly SPLs, then an audio taper pot would be best.
Whereas if you're just a tiny bit too loud for your band and being able to turn it down a touch would be handy, then a linear taper may be better. But it would be a hair trigger between 0-1 to get domestic SPLs with a linear pot.

Okay - thanks for that

[jackplug1]

Will implimenting this modification (Lar/Mar PPI-MV) affect the brilliant control, should I remove that pot and cap altogether ( I don't care for it anyway)
See attached diagram

[pdf64]

No, the LarMar won’t affect the brilliant control, provided that the you wire the brilliant control before (on the hot side) of the LarMar.

[jackplug1]

I have attached some diagrams and would be grateful if somebody could check them out to see if they are correct.
I have removed the 220k resistors  from the original schematic

[pdf64]

The brilliant control is wired up incorrectly. The cap should be in series with the control's variable resistance. The sketch puts it in parallel.

[jackplug1]

The brilliant control is wired up incorrectly. The cap should be in series with the control's variable resistance. The sketch puts it in parallel.

Thank you, I will correct that

[jackplug1]

After correcting that I wired it up. The MV works very well but the brilliant control causes distortion at when rotated completely counter clockwise for some reason.

[Fresh_Start]

After correcting that I wired it up. The MV works very well but the brilliant control causes distortion at when rotated completely counter clockwise for some reason.

I would simply take it out since you didn't like it pre-modifications anyway.

Is it possible that the 470pf cap in the "Brilliant" circuit got too much heat at some point during the process?  I don't know that it's the problem but that would be my first suspect.
I wish that I had a clever way to use that pot for something else but nothing comes to mind.  A Mid control always is nice IMHO; however, it would take some work to design and implement one in this amp.

Cheers,
Chip

[pdf64]

After correcting that I wired it up. The MV works very well but the brilliant control causes distortion at when rotated completely counter clockwise for some reason.

That seems weird. Is CCW max or min resistance?
Does the setting of the master vol affect the distortion?