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Different Kind of Amp Build (Merrell MA-12 conversion)

Discussion in 'Shock Brother's DIY Amps' started by pinchegil, Dec 18, 2020.

  1. pinchegil

    pinchegil Tele-Meister Platinum Supporter

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    I found a merrell MA-12 on craigslist for the cost of a large burger king meal. it is a 1960 kit push pull 6v6 (non-matching :( ) with a 12ax7a a 12at7 and a 6ax5 rectifier all vintage RCA tubes. I brought it up on the variac and it does work however it has stuck pots and will need rebuilding. But since it was a mono amp, do I keep the circuit for nostalgia's sake? This was a budget kit amp and I can't find a schematic. Or do I change the circuit . I don't really want to change the front appearance. thinking of putting jacks in back or replacing selector switch with a jack.
    merrell_front.jpg Merrell_guts.jpg Merrell_Rear.jpg
     
    gigante likes this.
  2. wabashslim

    wabashslim Friend of Leo's

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    I'd try to free up the pots before heating up the iron or spending more money. I assume you want to use a guitar with this? Wire up a speaker and use an adapter to plug into the best-working input (aux, probably) and see what it sounds like...could be heaven, could be hell. It might work OK but not give you the kind of sound you can use, being a hifi amp & all.

    FIRST - make sure you're not getting hot voltage on the chassis or anywhere else you shouldn't!
     
  3. pinchegil

    pinchegil Tele-Meister Platinum Supporter

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  4. jmp81sc

    jmp81sc Tele-Meister

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    I think you have everything you need for a nice head unit. I would use it to make a guitar amp, but I have no idea what the tube audio amp world would think of that.

    It would probably not be that hard to do schematic, then you could evaluate the circuit and decide if you want to modify it for guitar or start over. I would pull the tubes and see what kind of voltage the PT is putting out unloaded, and make sure the heater wires, etc. are working. If all seems ok then do a voltage chart, looking for unusual voltages but also to use for design purposes.

    A few Fender tweeds that come to mind are the 5E3 Deluxe, Harvard, Vibrolux, or the 6G2 Princeton. Add a 12AX7 tube and more possibilities open up.

    I would put a pilot light on the front panel and inputs and a fuse on the back
     
  5. jmp81sc

    jmp81sc Tele-Meister

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    BTW these never seem to show up in Southern California. If it has tubes in it everyone thinks it's worth $300.
     
  6. Nickfl

    Nickfl Friend of Leo's

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    Sweet find, do you have a schematic? Did it come with a cabinet of some kind or just that chassis?

    Also, do you have multiple conical homebrew fermenters in your kitchen? Or do you just have surprisingly nice cabinetry in your workshop?

    So many questions...
     
  7. pinchegil

    pinchegil Tele-Meister Platinum Supporter

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    It came just like that, I can't find a schematic anywhere but its pretty simple I am going to draw the schematic of it for practice. As for the cabinetry, when i got around to building out man land I chose a kitchen instead of a bar, Those are two 14 gal blichmans I keep them there for ease of clean and easier to maintain temp. brew days are a mash of brewing/drinking/playing guitar
     
    NSB_Chris and Nickfl like this.
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