I need Marshall 800 advice

RobV

Ambassador of Bedroom Wankery
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I have a 1982 Marshall JCM 800 4210 converted into a head. It was a 2 ch. 50w 1x12 combo. Let me make this known....I am not an amp tech and this would not be the amp I want to be my 1st project as I would like to learn how to mod but not here on this.

I do not know any amp techs where I live. We have 2 small Music stores but am able to get to the Pitt area quick enough. I do have trust issues with new service people being my experience in the car game I left behind. I am also not a very experienced player but I need to get this thing serviced.

My clean channel sounds fine until you turn both Gain & Volume up past 7 together or gain by itself but not as bad with volume lower. The gain channel basically is the same deal except the gain gets even fuzzier. I have read that these are known for it being on that side but I think this is more than that. The amp clean with gain low sounds decent even pushed some but thins out. It will get loud as it is a 50w but my Ibanez TSA 15w (6v6) seems to get louder & warmer.

I have owned a JCM2000 DSL 50 Head and it was definitely louder IMHO and sounded a lot better.

I have roughly $600 in this head...I traded an 89' SG Special I paid $600 for the 800. So left as is I should be able to get my money out of it but I would love to get it sounding right & do the couple mods I have read these need done which is move the reverb & fx loop after the master.

When I got the amp it had new preamp tubes in it & a set of Mesa power tubes that looked good but I did have a new set of Mullards and tossed them in. Sounded a little better to me anyway.

So your thoughts on what you might think the issue is or experience with getting amps worked on where or maybe cost expectancy or should I just unload it and get another head.....

To me in my head I just feel the 800 should be the end all amp but this may just not be the 1?

Edit to add I have tried swapping around pre-amp tubes and that's not the issue. I do notice a couple tube sockets seem looser than others and maybe need replaced?
 
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I would definitely have it checked out by an amp tech, as there could be a lot of things going wrong with an amp that age. I owned a 2205 (50-watt head version, same as yours) back in the '80's and that thing would peel paint and sounded better and better the more you twisted knobs to the right, so there is definitely an issue with yours. Yeah, they are fundamentally kind of fizzy-sounding amps, but they also have huge balls. It could be caps, transformer(s), bias, even the diodes. On the plus side, any decent amp tech has worked on dozens of them over the years and can likely diagnose the fix pretty quickly.
 
Yup. If ya ain't comfortable inside a tube amp, please keep searching for a good reference for amp repair in the area.
However, since you have shown an interest in modding, a best case scenario would be to hook up with an experienced Marshall enthusiast. You guys could work together, and you would get hands-on learning experience.

A very good forum that helped me and loves older Marshalls is http://forum.metropoulos.net
Unfortunately, their website is down right now.
 
if Pitt means pittsburgh, pa than there is a excellent tube tech in state college, pa... if your interested i'm seeing the people who would know on monday...

iu
 
Good to see you Syscokid. Anna and I serviced 27 guitar amps in 20 hours for a so called super star guitarist. Anna had never touched a guitar amp in her life
She picked right up on it. I showed her how to voltage chart a amp Had two dead amps Anna the voltages on the phase inverter are not correct
she did spread sheets on all the amps. I sold the Burst in my Avatar for stupid money. Anna likes drummers I had a private lesson with one of the best drummers
living it turned out to be an audition for this guitarist I turned down a world tour for next year. My band's happy I didn't go for it.
 
if Pitt means pittsburgh, pa than there is a excellent tube tech in state college, pa... if your interested i'm seeing the people who would know on monday...

Sorry been busy with work and such,Merry X-mas everyone :p Yes I mean Pittsburgh area. I am an hour or so south. I missed your Monday lol but yes I would be interested in getting some info on that tech if you want to pass it on?
 
Sorry been busy with work and such,Merry X-mas everyone :p Yes I mean Pittsburgh area. I am an hour or so south. I missed your Monday lol but yes I would be interested in getting some info on that tech if you want to pass it on?
what a coincidence, tomorrow is also monday & the deal is still good so i'll ask tomorrow night... the place is still around state college, pa...

iu
 
Sorry been busy with work and such,Merry X-mas everyone :p Yes I mean Pittsburgh area. I am an hour or so south. I missed your Monday lol but yes I would be interested in getting some info on that tech if you want to pass it on?

i heard excellent reviews for being tubular...

Engineered Sound

538 LONGBARN RD STATE COLLEGE, PA 16803
(814) 865-0870

iu
 
Yes up on the other side I am 30 minutes from Morgantown & 30 minutes from Uniontown.
when ii tell people that i live in pa they think i can walk to pittsburgh which is 4-1/2 hours west... manhattan is depending on traffic 2-1/2 to 3-1/2 hours east ie closer...

iu
 
Since the power valves were changed, I would recommend first having the bias tested and adjusted. Although both valves may appear to be functional, one may be spent.
 
Since the power valves were changed, I would recommend first having the bias tested and adjusted. Although both valves may appear to be functional, one may be spent.
That definitely needs checked but they are brand new Mullards.
 
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