1959SLP vs. JCM 800

Discussion in 'Marshall Amps' started by JM5010, Jul 4, 2020.

  1. JM5010

    JM5010 Active Member

    Joined:
    Nov 11, 2017
    Messages:
    187
    Likes Received:
    26
    I’ve been researching the Dookie Mod and was told by someone who has worked on Billie Joe’s amps that “JCM 800’s aren’t ideal for the mod”

    What is the difference between a 1959SLP and JCM 800?

    I know JCM 800’s are MV amps while the other isn’t. Are the voltages different, etc?

    What makes a 1959 more suitable for mods?
     
  2. scozz

    scozz Well-Known Member

    Joined:
    Jul 20, 2008
    Messages:
    3,631
    Likes Received:
    8,211
    Assuming this Tech is right, and I have no reason to believe otherwise, I’ve heard that the MV circut could/does affect other functions of an amp, like an effects loop.

    That doesn’t answer your question though, does it.

    But could it be because of the MV? That’s really the biggest difference in the two amps,...


    Someone more knowledgeable than me will come around soon, but this gives you a little bump.
     
    tce63 likes this.
  3. coolidge56

    coolidge56 Well-Known Member

    Joined:
    Jan 30, 2019
    Messages:
    882
    Likes Received:
    1,906
    Location:
    WA state hinterlands
    JCM800 has an extra gain stage on the Hi input. Here's how it works...on the 1959SL each input I and II uses one half of V1 the first preamp tube, then the guitar signal heads over to the 2nd preamp tube. The JCM800 Hi channel uses both halfs of V1. Guitar signal travels to V1b, across the Preamp pot to V1a e.g. 2 gain stages, then over to the 2nd preamp tube.
     
    neikeel, Kelia, dptone5 and 5 others like this.
  4. AlvisX

    AlvisX Well-Known Member

    Joined:
    May 31, 2011
    Messages:
    4,689
    Likes Received:
    9,084
    Location:
    I-55 Corridor
    JCM 800 is a production series ,not a model
    There is a JCM 800 1959 ,just like there is a a JMP 2203 .....

    I know sh*t about Billie Joe ,'cept he bought a Junior out from under me once
     
  5. JM5010

    JM5010 Active Member

    Joined:
    Nov 11, 2017
    Messages:
    187
    Likes Received:
    26
    This too. But let’s say a 1959 is modded so that it has the exact same gain stages as a 2203. Would they sound the same?

    I’m thinking maybe the voltages and transformers are different in both amps.
     
  6. Chris-in-LA

    Chris-in-LA Well-Known Member

    Joined:
    Jul 19, 2018
    Messages:
    1,356
    Likes Received:
    1,099
    Location:
    Los Angeles
    They use the same tubes. My bet is that if you take a 1959 and do the jcm800 mod to v1 it would sound very close to a 2203.
     
    neikeel and wntbtw like this.
  7. coolidge56

    coolidge56 Well-Known Member

    Joined:
    Jan 30, 2019
    Messages:
    882
    Likes Received:
    1,906
    Location:
    WA state hinterlands
    Remove a couple caps, change a resistor and wiring and the 1959 becomes a JCM800 2203 in an afternoon. There's not much difference. Ditto for the transformer voltages, though voltages for each have varied over the years depending on year and model. If I built a 1959 then converted it to a 2203 there would be no need to change transformers. You end up with 2 unused input jack holes, a Preamp/Master instead of Vol 1/Vol 2.
     
    JM5010, WellBurnTheSky and scozz like this.
  8. LPMarshall hack

    LPMarshall hack Well-Known Member

    Joined:
    Nov 18, 2009
    Messages:
    10,829
    Likes Received:
    10,110
    Location:
    San Diego, CA
    I’d like to hear that story
     
    JM5010 and Mitchell Pearrow like this.
  9. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member VIP Member

    Joined:
    Jul 2, 2018
    Messages:
    11,070
    Likes Received:
    19,095
    Location:
    Moreno Valley CA
    Me too
    :agreed: :cheers:
     
    LPMarshall hack likes this.
  10. Chris-in-LA

    Chris-in-LA Well-Known Member

    Joined:
    Jul 19, 2018
    Messages:
    1,356
    Likes Received:
    1,099
    Location:
    Los Angeles
    I could be wrong but the 1959 might be more suitable for mods due to the construction, especially if it is a turret board. The jcm800 amps all have PCB construction and that makes them harder to mod than if they had a turret board.
     
    JM5010 likes this.
  11. JM5010

    JM5010 Active Member

    Joined:
    Nov 11, 2017
    Messages:
    187
    Likes Received:
    26
    That could be it. Either way, the mod is commonly done on 90's 1959SLP reissues, which have PCB construction.
     
  12. Chris-in-LA

    Chris-in-LA Well-Known Member

    Joined:
    Jul 19, 2018
    Messages:
    1,356
    Likes Received:
    1,099
    Location:
    Los Angeles
    Right, not saying it can’t be done, just might be a little more involved.
     

Share This Page