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Sweet Vintage Amp Find

Discussion in 'Shock Brother's DIY Amps' started by dunner84, Aug 23, 2014.

  1. dunner84

    dunner84 Tele-Meister

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    Last week I was on the boat with the wife and kid at Hornby Island. We were told about a "free store".. Yes, a Free Store, where everything is free. Well my kid was excited to check it out so I indulged. This place is a big recycling depot on the island and there is a good sized store set up like a thrift shop. We wandered around for a while admiring the junk and as we were leaving I noticed something sticking out of a giant bin that was sitting outside under a canopy. I went over to take a look and this was sitting there on top of a toilet tank and surrounded by more junk. Well, being a free store, I had to take it.

    I did a little research and this thing seems kind of cool. It is a 1950s Masco ME-18 PA Amp. Turns out it is kind of a hot ticket in the harp world. It is obviously in rough shape. I was wondering if anyone here knew anything about these things. It seems simple enough. I am no.. It did not have all the tubes but it looks like it takes 2 6l6s and has some pre amp tubes I have never heard of before..

    I got it opened up and as you can see, I have to remove the inhabitants. It was actually an order from my wife.

    I have a busy weekend but I hope to get in and clean things up and posta few more pictures of the restoration.

    Feel free to offer any insight if you have ever seen one of these before.

    My estimate is that it would put out about 20w or so. Is there an easy way to test these transformers or these GE tubes?

    I found a few links to some sound clips on youtube. Mostly harp players and a and one with a guitar playing through, unfortunately the playing and audio quality is kind of shabby



     
  2. dunner84

    dunner84 Tele-Meister

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    pics
     

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  3. dunner84

    dunner84 Tele-Meister

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    more pictures
     

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  4. dunner84

    dunner84 Tele-Meister

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    What it is supposed to look like

    I probably won't find a top piece for it, but I think it will look pretty neat without it.
     

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  5. Tele Ted

    Tele Ted Tele-Holic

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    Cool, not bad for free!
     
  6. Telenut62

    Telenut62 Poster Extraordinaire

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    I reckon a few spiders are pissed off, nice find. ;)
     
  7. hackworth1

    hackworth1 Friend of Leo's Vendor Member

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    If one endeavors to restore a rusty amplifier, one must be very careful with the power transformer. It is possible that the PT is still functional, but too much rust may have rendered it useless. Importantly, the unknowing restorer can render it useless with aggressive clean up treatment.

    Use a moderately stiff soft bristle brush to stroke away all the surface crap. You won't be able to "deep clean" the PT unit. I have had some success wiping them with wd40. They can be painted. The bell covers may be removed, again with great care.

    Any errant scraping or gouging of the laminations is prone to short the beast. Too much rust may have already killed it.

    You won't find out until you get into it.
     
  8. fendrguitplayr

    fendrguitplayr Doctor of Teleocity Silver Supporter

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    Nice score and good luck with it.
     
  9. andyfromdenver

    andyfromdenver Friend of Leo's

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    Just imo, but I say take the knobs off, disconnect the output transformer, put those in a bin with other stuff, and trash it.

    If you're going to rebuild an old PA, start with one that was actually someone's cared for possession, imo, plenty of those in the world.
     
  10. printer2

    printer2 Poster Extraordinaire

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    I cleaned off too much rust from a 6V transformer and the iron ended up being a single loop secondary winding. Other than being careful not to go too crazy on the rust, could always paint over it, I would strip out most of the junk and start over. Gibson BR-6F, swap the 6SC7 you have for the 6SN7 in the schematic.

    [​IMG]
     
  11. dunner84

    dunner84 Tele-Meister

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    Thanks for all of the input and advice. I am going to attempt to restore it. At the very least if it is too far gone I will salvage as many vintage components as I can and build something new with it. That gibson circuit looks pretty sweet. I will do some research.
     
  12. Wally

    Wally Telefied Ad Free Member

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    That amp is in sad condition...neglected for years, right?
    Rusted laminates....leave them alone, imho. Do not disturb the rust.
    I don't know if I would fall off into resurrecting that one, either. There are places that will test those trannies under load...Mercury Magnetics is one such place....shipping two ways to find out what you have there.
     
  13. hackworth1

    hackworth1 Friend of Leo's Vendor Member

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    Andy's right. These amps and other similar units in good shape turn up on ebay all the time. If you are vigilant and patient, you can snag a good one for well under $99 including shipping.
     
  14. Nightatthehotel

    Nightatthehotel Tele-Holic

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    I'd say you put some effort into restoring the little guy and replace the hopeless parts and show everyone who would scrap it that it's still got potential.
     
  15. hackworth1

    hackworth1 Friend of Leo's Vendor Member

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  16. printer2

    printer2 Poster Extraordinaire

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  17. pasquale

    pasquale Tele-Meister

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    Worth saving. If you simply clean it and either find a schematic or trace it out you will be half way there. Would.change the filter caps right away before even powering up. Then follow some proven power up procedures and let the journey begin.
     
  18. GARAGE HERMIT

    GARAGE HERMIT Tele-Meister

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    the whole idea of the shop the OP scored the amp from is to keep item's out of the landfill site's, and re-use/re-purpose them, so i say restore it, if possible, if not use as many part's from it as you can, yes he could buy a working amp off ebay etc, but where's the fun in that, there's nothing i like better than getting an old radiogram that would have ended up in landfill and turning it into an amp, use the carcass for the cab etc, i'm not a "tree hugger" but it seem's that there's too much of the throw-away society going on, use a bit of imagination, and make something, out of junk,
     
  19. dunner84

    dunner84 Tele-Meister

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    So, I have been pretty busy lately but I have made some good head way on cleaning this mess up. I have removed and cleaned up the PT bell housing, I have cleaned up all the wiring, tube sockets and am now in the process of stripping and refinishing the chassis. I have pictures and will have them up soon. Before I dive into the electrical side of this, I thought I would post the schematic and have some of you tube amp pros take a look. I would love for some insight into the circuit.
     

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  20. printer2

    printer2 Poster Extraordinaire

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    6SJ7 pentode input, richer sounding than a triode although they can be noisier. Goes to a paraphase phase inverter. The top tube acts as a regular triode amplifying stage and the signal goes to its 6L6. The lower triode takes the output of the top triode but first a voltage divider knocks down the signal, then the lower triode amplifies. By amplifying it the phase of the signal is changed 180 degrees, the signal is then sent to the other 6L6. Nice little amp, hope it still has some life left in it.
     
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