How does the JCM 800 series work?

Discussion in 'Marshall Amps' started by slash38, Jul 3, 2012.

  1. slash38

    slash38 Active Member

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    I looked around on ebay and searched other place. I have seen original 2203 and then the mk2. What is the difference? I posted my last thread saying i want an afd but i just want it for the #34 mode. So it may just come down for me buying a stock 2203 and taking it from there.
     
  2. dixie hustler

    dixie hustler New Member

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    How exactly is a rainbow made? How exactly does the sun set? How exactly does a positrack rear end on a Plymouth work? It just does.
     
  3. slash38

    slash38 Active Member

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    whats the difference between a mk2 2203 and a regular 2203 i dont get it.
     
  4. dixie hustler

    dixie hustler New Member

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    I could be wrong, its happened before BUT a mkII 2203 is a jmp master vol. Then came the jcm 800 line. In which they dropped the mkII. I guess one could call the jcm's mkIII's but that would be silly. Lol feel free to correct me if I'm wrong. I have a 79' 2203 jmp it's about the same inside as the jcm 800. But cosmetically looks like the jmp which it is. Some say the jmp 2203 is warmer and not as harsh if you will. Guess it's a Good mix of both jmp and jcm. Hope this helps.
     
  5. Marshallhead

    Marshallhead Well-Known Member

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    Mk 2 means nothing, as it appears on 100 watt and 50 watt amps and combos (and JTM 45's too!) of both 4 input non master and 2 input master volume amps.

    JCM800 also means nothing apart from the cosmetic look of chunky sides and full width control panels which was introduced in about 1981/2.

    The model number, such as 2203, 1959 etc means more, and accompanied by the cosmetic reference of JMP, JCM800 etc and the clarification of Plexi or metal panel for JMP amps gives enough info to narrow things down to a particular amp and approximate time period.
     
  6. slash38

    slash38 Active Member

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    Oh see i thought it had a different type sound etc. But if it doesnt mean anything, then i guess its good because now im looking at the JCM 800 2203, and i just wanted to know if there was a difference.
     
  7. SmokeyDopey

    SmokeyDopey Well-Known Member VIP Member

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    Well.... It's not that it means NOTHING... Mk (Or Mark) is like saying "Version".

    So:
    Mk II = Version 2.
     
  8. dixie hustler

    dixie hustler New Member

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    I always dug Deep Purple MKIII. They got funky after Ritchie left.
     
  9. Brett Blackmore

    Brett Blackmore New Member

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    Hi,

    on the 8th day Marshall made the 1959 100 watt & 1987 50 watt non-master volume amps. They were the Super Lead amps and had the MKII marking and 4 holes. These amps were produced approx from 1967 until 1978 (roughly). They had 2 channels - lo and high.

    Very close to the 80s Marshall started a JCM 800 series which was to replace the previous Super Leads. They released the 2203 100 watt and 2204 100w master volume amps with 2 holes - some horizontal and some vertical. These amps are the holy grail for many purists as they had a valve preamp stage and no diodes (transitors). They had 2 channels as before - lo and high.

    However, Marshall still had lots of the 1959 and 1987 models left over, so they released them in this 'between period' as JCM800s with the JCM 800 head cabinets. Confusing right?

    Just a few years later into the 80's Marshall was under pressure to release a more modern version than the 2203 and 2204 but with 2 distinct channels (clean and gain), fx-loop and a little bit more gain. These were the 2205 and 2210 models. To get more gain Marshall added a diode clipping function - this was not always approved by purists.

    So in the time of the JCM 800 release there were 3 different overlapping models. Often there were releases with different transistors, different capacitors and a whole bunch of smaller items. some say one model is better than the other but some admit there were some bad models too.

    I personally want one of each!

    Cheers Brett
     
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  10. slash38

    slash38 Active Member

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    Cool thanks for sharing that story dude, now i understand. So after all the search im going for a jcm 800 2203. And then maybe Mod it?:naughty::slash:
     
  11. rjtm

    rjtm New Member

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  12. American Viking

    American Viking Well-Known Member

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    A 2203 is the same whether it's JMP or JCM800. Marshall used parts on a budget this means you may have different transformers and different brand parts so this kind of created that mystery that some amps can sound better than others.

    This goes for 1959 and 1987 models too. JMP or JCM800, as long as the model number is the same, the amp is the same.

    2210 and 2205, not worth your time. In all honesty though, if you're going through all the trouble to turn an amp into a #34 you could actually start on a 2210. The sound is very GNR. I don't like them though.
     
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  13. American Viking

    American Viking Well-Known Member

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    Just to add to the channel topic...


    The 1959/1987 models had a bright and a normal input. Basically one input goes into one half of V1 and the other input taps in the other gain stage of V1. Each input has it's separate volume. You could technically say these are separate channels but the two are almost mirrors of each other. Essentially once the master volume would be implemented into Marshall amps these two "channels" would be permanently bridged together with a few component value changes.



    The 2203/2204 master volume models had two inputs, a low and a high. The high input takes on both gain stages of V1 and the low input only hits on one gain stage. This is in very simple terms BTW, looking at the schematic you can see there's a little more to it than that as far as dumping some signal to ground and a few caps to smooth some stuff out but that's the basic idea. These amps are considered single channel amplifiers, as there is really only one channel.



    The 2210/2205 had two separate channels finally, a clean and a distorted channel. Dual channel amps were not among Marshall's strengths back then. There is a very present bleed through between the two channels. This was a new feature to Marshall amps and they hadn't quite nailed it. Most people that dig these amps aren't quite concerned with that anyway. If you don't use a clean channel, it won't matter.
     
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  14. American Viking

    American Viking Well-Known Member

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    1959 - 100w non-master volume
    1987 - 50w non-master volume
    2203 - 100w master volume
    2204 - 50w master volume
    2210 - 100w dual channel master volume
    2205 - 50w dual channel master volume
    4100 - 100w high gain dual reverb
    4500 - 50w high gain dual reverb
    2100 - 100w high gain master volume
    2500 - 50w high gain master volume
     
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  15. sccloser

    sccloser Well-Known Member

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    A mk II is a jmp or jcm 800 series for the most part. There is a mk III, it is a jcm 900 model 2500 or 2100 made only from 1990-1991. The jcm 900 SLX I believe is considered a mkIV.
     
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  16. slash38

    slash38 Active Member

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    2210 are heavy gain i feel. i heard some stock 2203 and i like em. not trying to argue just going with my opinion.
     

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