NAD - solid state "sweetness" from the '70s

Discussion in 'Amp Central Station' started by DeanEVO_Dude, Apr 19, 2019.

  1. DeanEVO_Dude

    DeanEVO_Dude TDPRI Member

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    I just picked up a beauty of an amp. It's a Gibson G20, and, the price was tough to beat at $130.
    It has had it's stock speaker replaced with a Jensen, and the metal ring with the numbers on it is missing from the power/volume control. Other than those two things, it is in very good condition. It needs to have it's cord replaced with a three prong one and, probably, needs to have the "death cap" removed, but I have not opened it up yet. It is extremely quiet, even at full volume, the only noise came when I turned on a dirt pedal. It might want some new electrolytic caps in the future, but for now, I quite enjoy it's clean tones. Heck, the pots aren't even noisy!
    I do have a question for others that have this amp:
    The tremolo does not engage untill the intensity knob is up to 6 or higher, is that normal?

    Take care all.
     
  2. galaxiex

    galaxiex Tele-Holic Silver Supporter

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    Gibson had quite a few of those G series solid state amps.

    G-10, 20, 30, 35, 40, 70, 80, 100 etc... I probably missed a few...

    The tremolo might be normal, or it might need new caps.
    The Trem circuit has a bias control, might need tweaking.

    Yes, they have a death cap.

    I have 2 of those amps, a G-35 and a G-70 that bought cheap on ebay (chassis only, no cabinet) for tinkering with.
    (probably were flood victims, the cabs and speakers likely got destroyed)

    Some Marlboro and other "stencil" amps from the era use the exact same circuit board. (I have one of those too)

    All made by CMI.

    Schematics are available....
     

    Attached Files:

    Last edited: Apr 20, 2019
  3. DeanEVO_Dude

    DeanEVO_Dude TDPRI Member

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    Funny that you mention Marlboro, I've got one of those as well. It's a GBO-12B, no trem or reverb, but it does have a 12" speaker. That one needed a little work, 3 prong cord, remove the death cap, someone had moved the transformer from under the chassis to the back... It is also a nice sounding amp, original speaker.
    I've had a hankering for these late '60s to early '70' amps and wanting to work on them...fix 'em up, play 'em. So far, these are my first two.
     
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  4. galaxiex

    galaxiex Tele-Holic Silver Supporter

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    Well... Interesting...

    I also have a Hohner that has a Marlboro labelled circuit board.

    001H.JPG

    img001.jpg

    The similarities to the Gibson are quite remarkable.

    This one was badly damaged (not shown) in shipping to me, so I gutted it and used the circuit board for another project.

    Another very similar amp is Paramount.

    I don't have one, missed the auction by a hair...

    001.jpg

    Cheers!
     
    Last edited: Apr 20, 2019
  5. DeanEVO_Dude

    DeanEVO_Dude TDPRI Member

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    Nice! Mine does not have reverb or tremolo. I really like the sound, even with the volume up, overdriving the amp. Not as nice a Plexi or 2203, but fine for me at home. My dirt pedals sound good through it as well.
     
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