Need help to determine value of '68 Plexi

Discussion in 'Let's Talk Vintage' started by DTM, Sep 20, 2019.

  1. DTM

    DTM New Member

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    '68 JMP 50 Plexi, model 1987

    Still has original transformers

    -It has been modified as follows:
    -Single channel operation with the 2 channel volumes acting as pregain controls
    -addition of master volume knob in rear of cabinet.

    Any help is most appreciated.
    Daniel
     
    Mitchell Pearrow likes this.
  2. GIBSON67

    GIBSON67 Well-Known Member

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    Need many pics, inside and out.
     
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  3. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member

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    Welcome to the forum, nice amp
    sorry I am no expert on values, but mods do bring the value down !
    Cheers Mitch
     
  4. Nik Henville

    Nik Henville Well-Known Member

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    Aww... c'mon Mitch
    Play nicely. The mods do a tough job,
    and do it pretty well too. I, for one, have NEVER seen any of our mods pushing prices down.

    :hippie::pirate::uk:
     
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  5. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member

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    :hbang::h5:
    :funny::cheers:
     
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  6. Gutch220

    Gutch220 Well-Known Member

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    once you drill holes in the chassis there's no going back
     
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  7. Matthews Guitars

    Matthews Guitars Well-Known Member

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    I'd see what similar examples are going for on Reverb. I'd say that your amp's value is almost certainly over 2000 dollars. If any mods that are done to it are reversible and no extra holes have been drilled that weren't from the factory, that'd help its value considerably. Pristine examples and ones that can be restored to all original condition tend to bring the most money, other than amps that have a documented history of being used by certain famous players.
     
  8. CoyotesGator

    CoyotesGator Well-Known Member

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  9. Adieu

    Adieu Well-Known Member

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    Too much to buy, not enough to sell
     
  10. neikeel

    neikeel Well-Known Member

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    I got £3000 for a 'facilitated' transaction on a '68 JMP50 Model 1987.
    Totally stock except for a replaced front panel (with top quality copy).


    We need pics
     
  11. DTM

    DTM New Member

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    OK...trying to upload pics but form says the files are too large. Will keep at it...
    In the mean time here arse some details..
    -Transformer numbers: 1202 118, 784-139
    -EL34 tubes
    -Solid State rectifier
     
  12. DTM

    DTM New Member

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    3000 British Pounds? That's fantastic!
     
  13. DTM

    DTM New Member

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    20190921_060637 (2).jpg 20190921_060649 (2).jpg 20190921_060910 (2).jpg 20190921_061000 (2).jpg 20190921_061228 (2).jpg
     

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  14. soundboy57

    soundboy57 Well-Known Member

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  15. DTM

    DTM New Member

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  16. Gutch220

    Gutch220 Well-Known Member

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    what Mains voltage does it use? (the rear selector knob is missing)
     
  17. DTM

    DTM New Member

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    Knob isn't missing, it was never there.
    What can I look at to determine mains voltage?
     
  18. neikeel

    neikeel Well-Known Member

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    The amp is an 'export' model and can be used anywhere in the world, just use the jumper on the turret board near the inlet. The UK models had two fuses on the back and mains and output selectors with Bulgin mains plug. Is yours Canadian?
    It is not a model 1987 (Lead)
    It appears to be a Model 1986 (Bass) amp. which often get less money. IMO the late 68/early 69 lead spec amp is the best plexi. Same tones as a 12 series (100w) but a bit more manageable in the real world.
    Importantly the transfomers and boards are all original.
    Although it has the master volume it appears that the amp has not been drilled so could go back to near stock condition. Those Dubilier caps are all original (someone might whinge that it does not have mustards) as Marshall ran out of mustards every now and again.
    Cab has, er.... patina but a lot of people like the lived in look, the original back panel and logo, correct grey feet are all bargaining chips for value, the missing correct era knobs will hurt value a little too (look on ebay for plexi knobs - silly prices! So bear that in mind.
    Next question is does it work and has it been played regularly?
     
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  19. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    It does look pretty good on the insides.
    It does not have the screen resistor update.
    Which means: if the amp is cranked up, the fuse will blow when newer output tubes are installed.
    And so: the update needs to be done for the screen resistors.

    Look on the inside of the wooden cabinet.
    Is it signed by Jim Marshall?
     
    Last edited: Sep 22, 2019
  20. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    Use Microsoft paint to re-size the photos.
    Save as: PNG or GIF format file.
    This makes the file size smaller, and allows you to post the picture.
     

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