Just got a free amp. Repair advice?

Discussion in 'Amp Input - Normal or Bright' started by Shockmaster, Oct 5, 2020.

  1. joe_cpwe

    joe_cpwe Senior Stratmaster

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    Looking at your picture, you've got a MM 2475-65
    Check out the model chart.
    http://www.pacair.com/mmamps/Misc__Info/Model_Chart/model_chart.html

    MM used the 65 watt power rating series in their first generation, which also used the 12Ax7 phase inverter. The 12Ax7 is on the left side in your picture too.

    Yours also has the original speakers, which are alnico, adding to the legend of your score. IF you decide to swap speakers for something lighter do not trash those speakers.
     
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  2. Miotch

    Miotch Senior Stratmaster

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    I didn't think what he has in it as stock speakers, were particularly heavy. Am I wrong ?? (OK if I am, I'm used to it).
     
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  3. StratoMutt

    StratoMutt Senior Stratmaster

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    Nice score! Looks like an early Music Man. :thumb:

    Amp repair is not for the inexperienced. Unless you know how to safely discharge the capacitors, don't even think about opening it up.
     
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  4. CB91710

    CB91710 No GAS shortage here Double Platinum Supporting Member

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    SCORE!

    That was a continuation of Leo's work there. Have someone who knows that they're doing get it back into shape.

    Would love to see Uncle Doug do a video on this one ;)
     
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  5. joe_cpwe

    joe_cpwe Senior Stratmaster

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    Yeah, I'm no expert on those alnicos either. My RD had a stock, mega-heavy ceramic, speaker in it. I bet the alnicos are lighter and pretty good sounding. Spec sheet says the amp is 60 lbs....not sure how much of that is speaker.
     
  6. heltershelton

    heltershelton BANNED Silver Member

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    thats 15lbs less than my ac30
     
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  7. pierce

    pierce Strat-Talker

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  8. jsegel

    jsegel Strat-Talk Member

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    I have one of these, an early one with the blonde tolex, used on tour for years in the late 80s/90s and again in the early 2000s. They're quite strong clean, can get great tone, but I almost never used the overdrive in favor of pedals. If I'm not making this up in my head, I think solid state pre-amp chip is a 4558, same as used in Tube Screamers. Mine has the EV speaker, it's super heavy. It broke a few times over the years, somehow not enjoying being in a trailer in sub-zero weather and then loading in and turning it on... oops.

    They push a lot of air, MusicMans. Once about 20 years ago I was at Mercenary Audio near Boston and the guy Fletcher (famous hyperactive audio dude, no longer there I think) showed us these MM stacks that he had used recording Aerosmith albums, they placed the speaker cabs facing each other with a ribbon mic in the middle, put one out of phase with the other and measured distances and cranked it to get guitar tracks. He said they went through speakers, but I don't know what he had in the cabs.
     
  9. Bill Moore

    Bill Moore Strat-Talk Member

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    You got a great deal !
    I got my MM dead, and had to bring it back to life. Still replacing caps, tubes, and flyback diodes, I think I only had about $100 in parts!
    I've read that the early ones used the LM307H op amps. My 81 RD One Hundred uses the TL072's, and I seem to recall 1 LM1458.
    Much discussion on the MM forum indicates chip swapping doesn't improve anything.
     
  10. Slartybartfast

    Slartybartfast Strat-Talk Member

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    YES it's worth fixing. Those are great amps.
     
  11. Glyderslead

    Glyderslead Strat-Talk Member

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    My music man 2x12 150HD was the loudest and best sounding hair straightener I ever had. So, why did I sell it and buy a Vox AC15 C1. ......? ...as I got older I just couldn’t pick it up and put it in my car boot any more!!! ............and now I’m down to a Katana........same reason.

    So, young man, get it fixed and use it while you can. You’ll never sound better,.

    Good wishes

    Mick
     
  12. Mr. Lumbergh

    Mr. Lumbergh needs you to go ahead and come in on Sunday, too.

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    Too cool man! That amp for only $FREE.99?
    I've done my own amp work before https://www.strat-talk.com/threads/noad-pic-heavy.317670/ but if you don't already have some experience working on circuits I'd leave it to a pro. As others have said, you can mess yourself up pretty badly if you don't take the right precautions.
     
  13. Dana Rudd

    Dana Rudd Strat-O-Master

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    Congrats on the amp. Glad you're taking to a pro to have it properly repaired.
     
  14. Stratattack72

    Stratattack72 Strat-O-Master

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    free is a real deal on that amp ! I played though one that had 4 ten inch speakers like a super reverb . Definitely worth getting fixed right !
     
  15. Scott Baxendale

    Scott Baxendale Strat-O-Master Gold Supporting Member

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    Definitely take it to your best local tube guitar amp and have it gone through. You will not be disappointed. It’s much better than any new amp under $1500.
     
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  16. Shockmaster

    Shockmaster Strat-Talk Member Silver Member

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    Just an update. Brought it to my amp guy and he got it back to life in a day. Amazing amp. Really excited to dig into it.
     
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  17. CAR63

    CAR63 Strat-Talker

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    Wow , you got a deal there ! Glad your tech got it done quickly . You're lucky you got a light ( ? ) one , according to the chart Joe sent above , my 212HD130 weighs 93 lbs. ! I knew it was heavy back in the '70s , but I was a younger man too !! Enjoy that sucker !!
     
  18. rolandson

    rolandson Most Honored Senior Member

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    Good fortune has smiled upon you indeed!