Marshall JMP Bass 1986 from 1971

Discussion in 'Marshall Amps' started by nrjdennis1, Sep 21, 2020.

  1. nrjdennis1

    nrjdennis1 Active Member

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    Hello

    A friend of mine is considering buying this JMP Bass 1986. It has been modded but the seller does not know what the mod is.

    Is anyone here able to tell from the pictures?
    Any info would be appreciated, including ease of reversing the mods...
    IMG_1838.JPG IMG_1837.JPG IMG_1835.JPG IMG_1834.JPG IMG_1833.JPG IMG_1832.JPG IMG_1831.JPG
     
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  2. neikeel

    neikeel Well-Known Member

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    Presume it is a Canadian model?
    The mod is just a pre-pi (standard Marshall) inserted between the treble pot wiper and the PI input cap. A simple useful mod (turn it to max and it is stock 1986).
    Shame they drilled the front panel as it is pretty pristine otherwise. Thankfully Matthews Guitars makes new repros indistinguishable from the originals (the chassis has a hole there anyway), should your friend decide to buy.
     
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  3. black knight

    black knight Member

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    The green insulation on the power transformer leads is something I haven't seen. Neil, does the transformer look original? To the OP: The gentleman who posted before me is an expert on vintage Marshalls and has a wealth of knowledge. You can bet if he weighs in, you'll have all the answers you need and the information will be accurate.

    Otherwise, beautiful amp.
     
  4. nrjdennis1

    nrjdennis1 Active Member

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    Thanks! I think this info is enough to base a decision on...
     
  5. neikeel

    neikeel Well-Known Member

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    Extra fuses and added insulation with no external access to high voltage on the back all point to the enhanced safety features of a Canadian (or Scandinavian) model. I am pretty sure the PT is original. Certain years they also had an internal fuse in the transformer itself (anyone know what years?)
     
  6. Guitar Dave T

    Guitar Dave T New Member

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    Great advice here already. Your friend might consider either:
    1. Leaving the master volume mod as is if he plans to gig it. It looks like basically the same master found on late 70's - early 80's 2204's, '2203's , JCM800's, which were plenty effective for getting volume to a manageable level in a live band context, or:
    2. Replacing the old school master volume with a PPIMV if he wants to manage at lower volumes. I mean, the front panel already has the hole drilled, right?
    BTW, huge 1986 circuit fan here. Enough so to take a used 1987x reissue and have it converted.
     
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  7. william vogel

    william vogel Well-Known Member

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    I’d take a bass circuit any day over a lead. Use a treble boost in front if scorching the front row.
     
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  8. nrjdennis1

    nrjdennis1 Active Member

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    Would you have any opinion of a reasonable price?
     
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  9. neikeel

    neikeel Well-Known Member

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    Sorry, I'm wrong side of the pond.
     
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  10. nrjdennis1

    nrjdennis1 Active Member

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    What side? I’m in Sweden:agreed:
     
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  11. neikeel

    neikeel Well-Known Member

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    Ah ok.
    US prices are higher and if you are prepared to ship you will get more.
    In the UK £1000-1100 is about right. Minus the hole it would almost be museum quality so £1800 if right person came along, but I am not sure who is buying these at the moment (I see lots of high prices on ebay and Reverb but not the expensive stuff moving, unless particularly desirable like a 64 JTM45 with rare extension cab!)
     
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  12. NewReligion

    NewReligion Well-Known Member Double Platinum Supporting Member VIP Member

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    Agreed. Looks like a Lee Jackson pre phase inverter master. Really terrible placement IMO.
     

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