NOAD - 1983 Marshall 4210 50 watt 112

Discussion in 'Amp Central Station' started by Dacious, Apr 2, 2020.

  1. Dacious

    Dacious Poster Extraordinaire

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    Couldn't resist this off Gumtree. Like Oz's Craigslist.

    $Aud700 or about $US430.

    Third one I've owned, second concurrently.

    No channel bleed, sounds FAT on the clean and the boost I can tweak although I'd rarely use it.

    Great reverb and even the G12T-75 is pretty smooth and well broken in. Needs a back panel and some tube sleeves.
    IMG_20200403_144237.jpg
    IMG_20200403_144252.jpg
     
    Jakedog, Censport, King Fan and 8 others like this.
  2. JayFreddy

    JayFreddy Poster Extraordinaire

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    Nice score!
     
  3. brookdalebill

    brookdalebill Tele Axpert Ad Free Member

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    Cool!
     
  4. gridlock

    gridlock Friend of Leo's Silver Supporter

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    I need that. Congrats!
    A very good/great amp.
     
  5. tah1962

    tah1962 Friend of Leo's

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    Very :cool:. Nice score. Congratulations.
     
  6. 11 Gauge

    11 Gauge Doctor of Teleocity

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    I got a 4210 back in '06 or so, and unfortunately, I didn't fare so well. It had the channel bleed issue, and mine had a really tired G12-80 in it.

    Also, someone had screwed around with it, to make it run EL34s, and they didn't really do that great of a job, IMO. They also seemed to screw up a bunch of other things in the process.

    The good news is the story has a happy ending (to me, anyway). In the process of trying to get to the bottom of the multiple issues with mine, I pulled the factory PCB and replaced it with a 2204-like turretboard, and continued tweaking and finessing it, as the years have gone on. Someone was kind enough to build me a head cab to load it in, and I've still got it, to this day (I could never get a return on all the custom stuff I've done, so I'd never sell it anyway).

    Anyway - enough of all my griping - kudos that you found a good one!
     
    Jakedog likes this.
  7. chris m.

    chris m. Poster Extraordinaire

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    I really loved my 4210, sounded incredible. I sold it when I got an Orange AD50 that arguably sounded better, but I miss it. It was a heavy bugger, though. Mine was set up to run EL34s from the factory...
    I believe these amps have essentially a pedal built in-- a couple of clipping diodes. I had an amp guy take those out and it sounded really great-- like more coveted earlier versions of the JCM800. So that's my advice if you want a classic JCM800-- buy one of these and get it modded back to the original spec-- kind of like "black-facing" a silverface Fender.
     
  8. naveed211

    naveed211 Tele-Holic

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    It’s my understanding with these that the diode only kicks in once you got past a certain point on the gain, like almost on full. Run it more around midway and it should be the classic 800 sound.

    Nice score! 800s are my favorite amps.
     
  9. 11 Gauge

    11 Gauge Doctor of Teleocity

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    Actually, the boost/drive channel in this amp is more like something from a BF/SF Fender amp (including the values of the tone stack components), but with the diodes shunted to ground after a cathode follower stage (your 'typical' Marshall would have the tone stack here, instead). The schematic shows antiparallel series pairs of 1N4007s, but mine only had a single antiparallel pair.

    The 1N400X types of diodes tend to have a forward voltage of around 570 mV or so, so my 4210's OD boost/drive channel would have clipped any signal bigger than that, while the 4210s that actually had the four 1N4007s would have clipped any signal bigger than ~1.14 V.

    ...Since the diodes fall at the end of the boost/drive channel's preamp, and are essentially shunted/hard clippers, their effect will pretty much trump any of the clipping at the prior two triode stages. There's a subsequent mixer triode stage for both channels after that, but IDK if you could really drive it hard enough to get it to contribute much add'l clipping, or how audible it would be in combination with the diode clipping before it.

    It just dawned on me that probably a really cool mod for this particular amp would be to put a 'compliance' pot in series with the clipping diodes - something maybe 10K or perhaps a little bigger. As you increase the series resistance, you'd decrease the effect of the clipping diodes. If you don't use the D.I. out on the amp, you could put the pot there. This would probably be way more useful than dinking around with different diode types or combinations, or maybe even more useful than eliminating the diodes altogether (they'd basically have no effect if there's enough series resistance, anyway).

    Oh yeah - almost forgot - it dawned on me way after the fact that the 4210 could potentially be a decent candidate to have its boost/drive channel modded to be more like what you'd find for the preamp of a Trainwreck Express or Liverpool. It would probably be a major pain pulling the PCB to change all the necessary components, though.
     
    Last edited: Apr 4, 2020
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