Another grid-to-ground tone robbing cap? (A1270)

[JJman]

I just spotted a grid to ground .002 (2000pf) cap on the reverb return jack of my '71SFDR. Looking at the schematics it looks like this was added with the A1270 and was not on the previous AB868 or AA/AB763. I removed the ones on the output tubes a long time ago with no problems.

Anyone ever remove this one? Is it another tone robber, only relating to the reverb sound? I'm thinking that brighter reverb might be a good thing on this amp. But maybe .002 is already above the relevant audible frequency in this location? Anyone know the frequency at which this one begins to do it's thing? Maybe I should replace it with a smaller value so it still prevents the boogie man from entering?

Of course I will experiment but maybe this has already been done.

 

[JJman]

I noticed a lot of microphony around the cap and it's connections. Removing it solved the microphony and did not brighten the reverb. I put a new .001u(1000pf) cap back there and no problems.

 

[itkindaworks]

I believe the reverb was changed a little on silverfaces(to allow mostly highs through?). This is what I've heard.

 

[Fuchsaudio]

That cap is there to control the resonance of the reverb return circuit. Replacing it, is wiser than removing it. It can also prevent possible oscillations from occurring.

 

[davemccarthy707]

chop it out I always do