#1
Hi can anybody tell me what this mod (besides the lack of tolex) is; the 2 added knobs on the right side. Thanks

#3
no way to tell by looking at the outside, need to open up the amp to see what those two pots are doing.
#4
Someone appears to have added some knobs to a Marshall.


The 80's were dark days. Everybody and his brother modded 800s, and stuff like this is more common than not. That picture doesn't really do us any good. If you can get me a high-res shot of the wiring I might be able to help.
That said, the usual thing to do with 800s was to add a post-phase inverter master volume, and add more gain. If I had to bet I'd say that what those knobs were for.
#5
I modded mine myself with help from

http://www.tone-lizard.com/Ultimate_JCM800.htm

There's some stuff to make it less thin sounding at low volumes and adding small amounts of gain in a few different places instead of modding the plate....don't do that,then ur 800 won't sound like an 800 nymore...then u might as well get another amp
Fender 70s Ri Strats w/various Dimarzios
Modded 1982 Marshall JCM800 2203

Boss DS-1,Dunlop Crybaby,MXR Phase 90,Ibanez AD9,Boss CH-1

Check out randy dobsons underground ,tell me what you think
#6
Another popular mod for JCM800s is putting in a resonance control, which is also plausible.
#7
Thanks. I bet these modifications considerably affect the value of the amp right?
#8
I wouldn't think so, I wouldn't exactly call a JCM800 a collector's amp. Some one might get bitchy about the panel being drilled out for the two pots, but I mean.. other than that, it will probably be in the same range as most other JCM800s (~$800-$1100 or so). It's not really a vintage amp where a collector is going to make a big deal about the caps, resistors, OT inside. Replace the mustards from inside an original JTM45 with Mallorys, for example, and watch it's value plummet.
Last edited by al112987 at Sep 21, 2009,
#9
If you do mod it be sure you can put it back stock....unless you have a reputable technition like lee jackson or someone mod it...that may cost 500 bucks hahaham..I did mine for about 2 dollars...lol...sounds awesome....
Fender 70s Ri Strats w/various Dimarzios
Modded 1982 Marshall JCM800 2203

Boss DS-1,Dunlop Crybaby,MXR Phase 90,Ibanez AD9,Boss CH-1

Check out randy dobsons underground ,tell me what you think