Gibson GA-40 Coupling Cap Question

[Fletcher Munson]

The Gibson GA-40 has an unusual coupling configuration between the first gain stage and the volume control that I don't quite understand. On the trem channel between the plate of the 5879 and the Ch. 2 volume control, where you would normally see a single coupling cap, there are a series of .005uf capacitors separated by 1M resistors going to ground. What's the purpose of this configuration? How does it work and what were they trying to accomplish?

http://www.gibson.com/Files/schematics/GA40LesPaul.JPG

[loudthud]

That is a high pass network that filters out the Tremolo LFO signal from the guitar signal. It's used on some Vox amps but I don't remember seeing it on a Fender or Marshall. The LDR type tremolo doesn't require the filter, output stage bias wiggle tremolo cancels the LFO signal in the output transformer, well, most of it.

[Fletcher Munson]

I'd never really thought about filtering LFO. As you say, the more familiar Fender circuits handle this filtering sort of "invisibly." Thanks for the explanation.

After a little more research, I see that some people have recommended modifying the GA-40 by removing or bypassing this filter network, claiming improvement.

[loudthud]

A lot of the way it sounds without the filter depends on the power supply, the output transformer and the speaker. You might want to experiment by eliminating one or more stages or change the cap values.