Noisy GK 250ML MkII. Any good advice?

[dielektrikum]

Hi!

I am trying to get rid of high level white noise generated some where in the preamp section (the charachter of the noise can be controlled with the EQ). Are there any known causes for this? The opamps *seem* to be in order.

Any constructive input is most welcome!

Thanks a lot.

[J M Fahey]

Google for the schematic so we all talk about the same circuit.
Anyway, it's a 2 channel amp, with effects.
Is it present on both?
In what conditions does it appear? (settings).
If it appears only on the highest gain settings, it might even be normal.
Which controls affect it, which not?
Well, that's a starter.

[dielektrikum]

Thanks for Your answer!

The schematics can be found here: http://www.about-guitar-amps.com/guitar_amps_schematics/gallien_krueger.htm (free registration rquired). It is an 250ML MkII. I will try to answer Your questions as soon as I get the amp back. The noise appears when setting the amp in a "playable" mode in terms of gain and volume. The noise appears in both channels and seem to be independent of the echo and chorus effects.

Maybe I should record the noise to make my point more clear, but anyhow it is at a disturbingly high level compared to the amplified guitar signal!

I would say that all controls in the signal chain affect the noise (the volume and gain in terms of level, and the filter... filters the noise). Does that make any sense?

I was thinking of dried electrolytic capacitors. What do You think?

Again.. Many thanks for Your shown interest!

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[J M Fahey]

OK, download it and post it here as an attachment, meaning attach *your* copy and not the  link to guitaramps.com, so any forum member who feels interested may see it and contribute, without going through the registration or logging everytime.
You can even post it to some "open" site such as imageshack or some similar one, so it's seen automatically here.
I can't talk about capacitors or whatever until hearing it, post some MP3; "a noise" can be anything.
Good luck.