forgot to attach the schematic:

http://img850.imageshack.us/i/moddedpreamp.png/


Sound Clips:

Dist
http://www.filedropper.com/distex

Clean
http://www.filedropper.com/cleanex

I dont know a better spot to upload an mp3, maybe you guys know

Thanks,
Kevin

Is this the schematic of your mods.?
I assume it is a JCM 800 of some derivation. How did it sound before you modded it.?

I don't know without going through your schem and comparing it to a stock 2204/2203.....
Are your tubes up to snuff. The only real way to tell is to change them out.
maybe compare your coupling caps to stock values. Cat by-pass caps also. You can get some pretty big increases in bass response from a relatively small increase in cap values.
Other than this, I do not have much for you.
Tubes
Bias
Cap values
Good Luck

I do not really know. So now we are talking about an amp that sounds "bassy" To You. Another player with another guitar and another cab might think he was in Tone Heaven. If I had to guess I would say:
speaker(s)
tubes/bias
caps
I am not a guitar guy, but you could also play with your pickup heights.
But it seems like the other things I mentioned would be more likely culprits. Do you have some speakers you can try, along with different/new tubes.?
Your first cat by-pass cap is already pretty small. It may seem counter productive, but what if you raised that value.? Maybe a 2 or 4.7 mic.
Are you really hearing too much bass, mud, boominess.? Is it possible you are hearing, thin, dull weak, flat.? Hard for me to say. We all hear things differently and use different words to describe what our ears are hearing.
I don't know man.
Guess I would start with tubes and then speakers......
Good Luck

Hey Kevin -
No I did not listen to the clips. They are so often useless for defining "tone". But if your amp is REALLY sounding bad......I will give them a listen now.
If I can help you with parts, send me a PM/email, and let me know. You guys have At Least one very good tube dealer....... http://thetubestore.com/
Best

75 Watt "green backs"......?
Are you talking about the GT-75 speakers.?
Not my favorite at all. But Marshall sold a billion of them, so who am I to complain. Though, I think those speakers tend to be very "bass heavy" and mid-scooped. Just My Opinion.

Hmm I think I can borrow a cab from a friend. I never took that into conciseration because everyone always told me that the old marshal 1960a cabs from the 80s was gold. ill give this a try later and get back to you. Btw your very helpful I greatly appriceate your help

Hi there first post ... the only place where I could see some highs being removed based only on the schematic is on the voltage divider before V2, but that would only affect the clean sound.

You have the normal 470k/470pf //470K arrangement but with the way your switching is done you only have the bypass cap in the signal path when in OD mode so you get the full treble peaking effect there. When in clean mode the 470K/470p goes to ground and will cause the opposite effect, draining quite a bit of highs.

It should be easy to take it out just to see what happens to the cleans. If it improves some, you could install it again and put another 470pf bypassing the other resistor to get treble peaking on both modes ... this won't result in exactly the same treble peaking for the OD mode as before (because each side will be pulling a little treble from the other when shorted to ground) but I think the difference would be minimal.

About the overall darkness of the amp it could be the speakers as has been said before .... the circuit is straight up 2204/2203 other than the switching so it shouldn't be dark!

Btw, I'm using the same pot to ground on the MV method for volume boost in my amp (Plexi 50 made into switchable cascaded preamp), simple but effective.