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JMP 2203 question

Posted: Thu Oct 08, 2009 11:56 am
by Johnny
A quick question:

anyone here know if there's a difference between say a 1983 JMP 2203 or a 1977 JMP 2203? Like do they have different levels of gain or are they the same?

Re: JMP 2203 question

Posted: Thu Oct 08, 2009 3:26 pm
by jtr654
The early JMP with master volume had 6550 instead of EL34. I have a 1977 50 watt head and 1977 50 watt combo and both have 6550 in them they can be rebias for EL34.

Re: JMP 2203 question

Posted: Sat Oct 10, 2009 9:05 am
by Johnny
Oh. Well, thats great since I prefer EL34s over 6550s anyway. Thanks. I bought an '83 2203 100W head.

Re: JMP 2203 question

Posted: Sun Oct 11, 2009 10:58 am
by oipunkguy
from my understanding the circuitry is the exact same, just a different look. JCM 800 collectors always seem to prefer the vertical input version, because they are suppose to be made better. the horizontal versions (after 1983) was a cost cutting measure so both inputs could be installed on the same circuit board. I'm not quite sure why that is a big deal, but hey there you go ;)

Re: JMP 2203 question

Posted: Tue Oct 13, 2009 11:07 am
by Johnny
Different transformer, less gain. The transformer is only used in teh 2203 JMP making it unique sounding. And mine sounds freakin' great.