What is the function of this cap?

[psychepool]

Belows are the schematic of Mesa Rectoverb clean channel and CJ11 tonestacks.

Recto

BA53BC71-51B8-4160-BE34-80ECC9704B03.png

CJ11

E48942CE-311E-4896-91CC-718471AF867B.png

They have some pF capacitors at volume pot.
I know the caps that install between the volume 2/3 pin is a bright cap.
It passes the high end when volume pot sets to low volume.

But I don't know about the caps that checked with red circle.(caps that install between volume pot 1/2 pin)

What is the function of these caps?
What happens when higher or lower the value of these caps?

[Orson Maxwell]

Hi!

This is gain pot tone compensation, however in the second case it is a bit more funny. Here is the basic frequency response of these networks (The curves are 2-4-6-8-10 rotation of the pot):

rectoverb1.png

rectoverb2.png

[Travis_HY]

The 10 pF is sort of a high frequency shunt; probably to quell oscillations. 10pF is very small and would probably not affect any of the audible guitar frequencies. You'll notice it take off more high end if you increase it's value. 10pF-100pF is range of caps I found could be useful. The 250pF might be useful in that particular example provided but I find it to be too dark a value in most applications