Vintage Guitar Amplifiers

Marshall 1968/1969 50 Watt JMP Plexiglass (Plexi) Head

You know what this is - up for auction is an incredible piece of Marshall history - this was recently acquired by me for investment, along with a companion 8x10 Model “1990” Marshall cabinet (not part of this auction) from the same era, but because I am also a huge fan of the Tom Murphy Relic Gibson Les Paul models (or similar higher end Gibson Custom Shop Relics), I figured I would see if this could get me an equivalent value and/or trade. If this does not sell, that is no problem, because it should increase in value again as the market slowly comes back - especially with the matching cab with brown two-tone basketweave cloth.

The amplifier sounds as you would expect - nice and warm with a great bass response, which is especially useful with the channels jumped. Can be super loud, but with a very smooth onset of volume. Crunch tone to die for with my Les Paul - sweet and chimey with my reissue Strat. The pots work great and there is no scratchiness. Each knob affects the sound as one should expect - not always the case with all amps. It sounds like one of the tubes may be slightly microphonic, but I have not even had a chance to take this to my normal amp tech for the standard evaluation and top-to-bottom check that I always do with all my amps. I figure that someone that might purchase or trade for this may want to go to their own tech in any case - getting it biased with a nice set of NOS tubes.

From what I can see myself, it has a replacement lay down power transformer, but the output transformer (the important one to sound) is the original with code 784-139.  The choke appears to be original as well.  There also appear to be a few other electronic component changes when you look at the photo (received from previous owner) of the innards - I have not opened it up myself to see under the hood. If I decide to keep it and take it to my tech, I will take photos of the innards at that time - especially if anything is changed. I am hoping that someone can advise me if this is the lead, bass or (possibly even) organ model based on the guts shot photo (NOTE: a friendly E-bayer advised that this is the lead model), but in any case I am advised that changing to any of these circuits is an easy prospect with a few component changes. Tolex looks great - with a seamless repair being possible on the top where it is slightly pulling up. I have not even attempted to clean this, but I bet a pro can return this to showroom look with a little bit of work.

This is an auction for the US and Canada only - I will ship fully insured by US Postal Service to the US and Canada only - no other shipping service is available. Please make immediate payment and No returns are accepted - you are bidding to win and keep this sweet vintage piece, as we are dealing with a piece of equipment that is now over 40 years old, but I will box this up extremely well. Any photos including the Marshall 8x10 cab are only illustrative and the cab is NOT included in the auction.

Here is a quote from The History of Marshall - The Illustrated Story of “The Sound of Rock” by Michael Doyle (page 28):

“As the years passed by, Marshall were making small but continual changes and refinements to their amplifiers, and by 1968-69 they had built what was in my view the best amplifier since the JTM 45; the 1969 50-Watt. Every one of these that I have owned has had the capacity to provide a sparkling clean sound, through JTM 45-like crunch, to a distortion that’s just on the sane side of heavy metal; and it’s all available at the twist of the volume knob. Great stuff!”

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