resistor near the vol pot

[castor]

Hi to everyone...

I saw in some pics that sometimes KF put a resistor between the vol pot and the pin of the tube.. soldered directly to the pin of the tube (francesca vs kelly pics)
Have someone tried this on his express? Is this only to reduce the total amount of gain or does it act like a filter? which vale did he used?

castor

[roberto]

They are from 820R to 470k. They reduce blocking distortion and acts like low pass filter (they roll off the higher frequencies) due to the miller effect of the next triode.

[Fischerman]

I thought it was for stability (due to the miller effect thing above). I'm no expert on the little tweeks KF made but I always thought it was a pretty low value...820R to 1K...I had no idea he went as high as 470k. Really?

I have also read that a grid stopper actually hardens the clipping due to positive grid current. I wish I could post it but it's just an old Ampage post (from a very knowledgable guy) and I don't have his permission. But if KF did add this resistor for stability and usually used values in the 820R-1K ballpark then it would seem to all add up...because it would appear that KF only used this resistor when absolutely necessary AND (it appears) used the smallest value he could get away with.

[fishy]

I think the two previous posts cover the subject.

Roberto covers the general use and why.
Fischerman is correct from everything I have seen when you apply it to a trainwreck.

Pete