calling all marshall mod guru's....please help...

[germanaircooled]

Modding my 78' 2204

Hello - I'm looking to produce a a combined saturated marshall brown sound + newer type saturation with a tight bottom...not askin' for much right? I have the cascaded model that has had an effects loop added with some kind of "goop" to cover component values. This amp has a huge amount of headroom, that I'd like to change? It is very load. I've heard that some of these older jmps have very high voltages. I think this is one of them, and I know that makes it hard to get any output tube clip and be able to keep what limited hearing I still have....

Please help...I could use some schematics, and or values, etc.

Thanks to all...

[Bob S]

Welcome.
Lotsa reading & info in the Marshall section.
It's all there...
Bob

[germanaircooled]

thanks bob...

[danman]

Most of the late 70's 2204 amps that I have messed with actually have a very low plate voltage of 370-380ish. In the 80's they went back to the higher voltage PT's in the JCM800's. If your's still has the original PT you should find the plate voltage to be below 400v. I have had success with dropping the preamp voltages a little for more of that liquid lead saturation sound. Try playing around with the two large preamp dropping resistors located right next to the bias pot. It may have a single 10k there or a combo of 10k/8.2k if it has not been modified.

[M Fowler]

The website is down but I saved his instruction info on modding 2204's

[roberto]

Don't personally like them too much.