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Marshall JMP-1 serviced at Plasma Music

Here’s a Marshall JMP-1 MIDI valve pre-amp that I’ve just serviced.

I’ve just changed the valves and PSU capacitors, cleaned up the metal work and implemented my ‘Live-for-Ever’ battery mod’.

The serial number indicates that it was built in early 1992 which not only makes it twenty-eight years old and one of the first off the production line.

The first MIDI valve pre-amp (I think), the Marshall JMP-1 has always been a really under rated bit of kit, despite the fact that named artists such as Billy Gibbons (ZZ Top), Phil Collen (Def Leppard), Iron Maiden, Megadeth and many more, still use them even today. In production for well over ten years, that’s got to say something about it.

The JMP-1 is not a modeller like modern stuff; it’s the real thing, just with MIDI. Run into a valve power amp (or two), it just sounds amazing and the quality of the speaker emulated outputs is definitely good enough to run straight into a desk or your DAW. Note, that alkthough the outputs can be switched to +4dBu, they're unbalanced so you might want to think about either running them into a D.i. box or a balancer (in fact I have just the thing), first.

They now go for between £400 and £700 (yes, £700). If you can pick one up nearer £400, then I personally think it’s well worth it.

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