Jtm 45 With El34s?

Discussion in 'Let's Talk Vintage' started by chard, Feb 9, 2019.

  1. chard

    chard Active Member

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    Does anyone know if any of the last MKIV JTM45 to leave the factory had EL34s fitted instead of KT66s?
    Thanks
     
  2. neikeel

    neikeel Well-Known Member

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    AFAIK no.

    If it is a late amp (66 and 67) then the OT number will be stamped on the end bells

    784-103 will be KT66s (and will be a JTM45)
    784-128 will be EL34s and typically steel chassis for a JTM50, there were some odd alloy block end with -128s, tube rectifiers and JMP front panels

    What have you got?
     
  3. Ned B

    Ned B Member

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    I think it would be possible. the Drake 128 came out in 02/1967 which was a transitional period with the final ali-chassis amps still being built.
     
  4. ampmadscientist

    ampmadscientist Well-Known Member

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    It is possible for the amp to use EL34s, but not from the factory.
    More than likely, KT66 would have been substituted with 6L6 or 5881, which is the closest equivalent.
     
  5. Ned B

    Ned B Member

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    I have seen transitional 100s that had the JTM45 front panel/white back panel, ali-chassis with 1203-60 PT/1202-119 OT so EL34 from the factory. At that time there were a lot of changes in process. New transformer models, chassis material, changing panels. There are some odd combinations of features then leading up to the black flag period.
     
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  6. chard

    chard Active Member

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    Thanks for the input gents. It’s an old MKIV super tremolo head that I’ve looked at that not been used in years. It’s currently sitting with EL34s in the power valve sockets but there’s no guarantee that it ever used them. It has the 784 103 transformer fitted but I suspect it could be toasted given the wrong valves that are fitted as well as the fact that the rectifier value has lost its vacuum and turned rather white.
     
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  7. neikeel

    neikeel Well-Known Member

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    That would have used KT66s originally.
    It is probably a Trem not a Supertrem.
     
  8. Ned B

    Ned B Member

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    Chard's correct. 096-7042-17 Marshall Bluesbreaker Chassis 1965.JPG
     
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  9. chard

    chard Active Member

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    As above it has white panel marked super tremolo.
     
  10. kuli

    kuli Active Member

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    The 'Bluesbreaker'-amp. Get it!
     
  11. neikeel

    neikeel Well-Known Member

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    I stand corrected. Mine is later gold plexi version.
     
  12. bluesbreaking

    bluesbreaking New Member

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    I have an early 1967 gold JTM45 front panel, 784-128, tube rectifier, aluminum chassis, and cast block ends. Here is a video of it - >
     
  13. neikeel

    neikeel Well-Known Member

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    That is a rare bird. Btw what rear panel do you have and what model does it say?
     
  14. bluesbreaking

    bluesbreaking New Member

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    Back panel is white and stamped with Serial #1292. Not stamped lead or bass spec. Front panel indicates JTM45. I have only seen 2 others (online only) with the same exact specs (784-128 OT, JTM 45 front panel, white back panel, aluminum, E34 power tubes, tube rectifier etc...).

    It's a special amp. At the time that I got it, I was not familiar with all the JTM45/mid 60s variations (RS OT, Drake 784-128 OT, Drake 784-103 OT, Tube vs. solid rectifier, Black Flags, varying face plates, EL34s vs. KT66s, aluminum vs. steel etc...) from the mid 60s.

    I just thought "great a JTM 45 from the Bluesbreaker era (green, clapton, taylor)... I'll take it." It had been modded for high gain which isn't my thing, but it was easily switched back to spec with some NOS parts by George M. The original OT was rewound by Chris Merren. The amp sounds great. I wish the OT was not rewound of course but I can't imagine the amp sounding any better than it does. I could possibly track down an original transformer without the rewind but I can't see that improving the sound of the amp and I'm not sure what it would do to its value either, so I have not bothered to this point. I would have preferred it to be able to run KT66s, but the EL34s sound mighty fine.

    Recently, I picked up a newer JTM45 THW for my KT66 fix... for now. I still hope to pick up a 65 or 66. Not sure if I want to go with a Drake or RS OT from that era.

    It's funny/ironic how one could own 4 or 5 mid 60s JTM45s yet the specs and tones would be slightly different. However, they all seem to have very similar tonal characteristics at the same time.
     
    Last edited: Feb 14, 2019
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  15. pedecamp

    pedecamp Well-Known Member

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    Sounds like a good project amp to restore, go for it and have fun with it. :yesway:
     
  16. eastsidecincy

    eastsidecincy Active Member

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    @bluesbreaking.....that is one of the best sounding Marshalls I have heard...great playing too !...:jam:
     
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  17. neikeel

    neikeel Well-Known Member

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    I had a similar one to the one in bluesbreakings clipsand it sounded just as good. Unfortunately had to sell with some other nice pieces to raise some cash. Thankfully have some other nice kit to fill the void.
     
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  18. bluesbreaking

    bluesbreaking New Member

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    I feel your pain. I had to a let a 69 strat go last year. That was an OUCH moment for sure. Best strat I had ever played or heard in person. Including pre-cbs.
     
  19. Kats

    Kats New Member

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    Cool amp bluesbreaking! Curious about the PT if it's a -55 or a -118? If a -55, maybe that amp was made right a the switch from kt-66s to el34s and it's like a stock JTM45 with a different OT (or a replacement from back in the day?). Very nice OD - creamy!!!
     
  20. doctorbaster

    doctorbaster New Member

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    I have a 67 jtm 45 alloy chassis, block ends, 784-128 ot, 1202-118 pt, RS 20H choke.
     
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