New build - Martin 112T styled amp

Discussion in 'Amps and Cabs' started by Leonc, Feb 19, 2012.

  1. Leonc

    Leonc Wild Gear Hearder Gold Supporting Member

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    Well, I guess I'm officially addicted to building amps, LOL. The Martin 112T was built by Dearmond-Rowe back in the late 50s. It's very much in the 5E3 vein, circuit-wise, though it is not identical and the transformers are rather different...and it has tremolo.

    Anyway, I've been following the market on these for maybe 4 or 5 years and they've been pretty high for quite a while. Several years ago, they were routinely going for over 2K, lately when they've come up for sale--which is pretty rare--they're fetching more like 1300-1700 or so. This is still on the high side for a little amp like this, which you compare it to something like a Silvertone 1482 (which seem to go for like 350 bucks or these days, if they're in great shape). So I decided to build one. I'd been toying around with the idea for a while but figured the transformers would be to hard to duplicate. But after talking with a few people recently, I said the hell with it, I'll give it a shot.

    I bought some great transformers (well I think so) from Magnetic Components. I considered using Mercury's "tone clone" transformers for this but after consulting them, I thought the amp would sound much better with a PT that produced lower B+ voltages. IME with their Magnatone tone clones, they come out too hot with today's higher AC voltages. So I'm using a PT with a 275-0-275V winding but I'm using it with a GZ34 (rather than a 5E3) and I'm getting voltages that are quite close to the schematic. If you use the MMs I think you'll come out way too high and the amp will sound too "new" and sizzley.

    Like all of my build projects so far, I learned quite a bit in this process. The coolest trick I picked up this time was a technique for orienting the OT so as to minimize hum. Many thanks to Jerry Glass, Blue Strat, donnyjaguar, slider313, trobbins, Gary Croteau and the other guys who helped answer my questions and gave me pointers along the way!

    The rest of the parts were very straight forward, other than the varistor in the trem circuit (these are what Magnatone used in their famous vibrato circuits). Anyway, finished up the chassis yesterday and played it with the band just a couple hours later. Since I used the same generic chassis that I built my Grinder (GA-40) on in December, I was able to plop it into the same cab and it worked like a charm. Boy...that was the most fun I've had playing in a while, I must say!!

    Like the 5E3, there's a lot of natural, rich gain on tap and it cleans up extremely well from the guitar. As you'd guess, the basic tonal personality is tweedish--harmonically balanced and rich cleans that gradually move into roaring overdrive. And the amp just LOVES my single-coil guitars and eats up my pedals as well! The humbuckers guitars I've tried through it seem to fare better than through many smaller tweeds I've played through, much to my surprise and pleasure, but you don't have the clean headroom you get with the SC pickups, of course. One of the things I love about it is that it cleans up quite well from guitar vol and pick attack changes but doesn't dramatically lose volume.

    I'll be working on a cab for it over the next week or two and will post more shots as progress is made.

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  2. Mattbedrock

    Mattbedrock Silver Supporting Member

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    Leon, you're at it again. Go man, go.
     
  3. esoteric pete

    esoteric pete Member

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  4. smolder

    smolder Gold Supporting Member

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    Looks like fun. Can't wait to see the cab ; )
     
  5. big mike

    big mike Administrator Staff Member

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    Sweet. Subscribed!
     
  6. slider313

    slider313 Silver Supporting Member

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    Cool! I can't wait to hear it.
     
  7. Leonc

    Leonc Wild Gear Hearder Gold Supporting Member

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    Thanks guys. Just got pretty much all the wood cut; still need to do the baffle hole but everything else is now cut. Just found what looks like some unusual, check-pattern grill cloth too :aok!! ... And once again, I'm really lovin the Eminence Swamp Thang...once it's broken in, it just seems to do everything I like about old Jensens...and none of the bad stuff. It's like a Super Jensen, LOL!

    Hey slider! Hard to imagine it'll sound just like either of yours...but what I like about it, among other stuff, is that it sounds real healthy but doesn't sound new, if you know what I mean. It sounds/feels like it's been around the block. I love MC's transformers (I think that's a big part of the reason) and I have always gotten great advice from Mark S over there.
     
  8. slider313

    slider313 Silver Supporting Member

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    Leon, those MC transformers look about the same size as the originals. The circuit is close to the 5E3 but the iron is much bigger. That's a big part of the sound.

    I used a MC tranny for a '66 Bandmaster repair and it sounded identical to my original.
     
  9. Leonc

    Leonc Wild Gear Hearder Gold Supporting Member

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    Dig it, Mike.

    Update - some progress shots on the cab. The front baffle is mounted at an angle I think I'm going to do a Magnatone-type front design with a "valence" mounted in front of the recessed part of the baffle, on top. I'll mount my logo/badge there. So its appearance will diverge a bit from that of the Martin...but it'll still have a vintagey kinda thing going on.

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  10. big mike

    big mike Administrator Staff Member

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    Big ups!! Nice dovetail work there Leon.
     
  11. waggclan

    waggclan Par 4 Holer Gold Supporting Member

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    Indeed! Very nice woodworking Leon.
     
  12. Leonc

    Leonc Wild Gear Hearder Gold Supporting Member

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    Thank ye gents! My woodworking and tolexing skills, while having improved over the years, are still pretty primitive when compared to a real pro, but thanks for the compliments, much appreciated!
     
  13. GA20T

    GA20T Member

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    Good job Leon, and one of my favourites. Looking forward to hearing this one.
     
  14. dewman

    dewman Gold Supporting Member

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    Need a beta tester lemme know! I used to own a DeArmond R15 and my good friend Slider313 now owns it and also a CF Martin 1x12!!!
     
  15. Leonc

    Leonc Wild Gear Hearder Gold Supporting Member

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    GA, Dewey - thanks!

    Dewey, well, seeing as it's just for me, I probably don't need an actual beta tester per se, LOL, but it would be nice to get an opinion at some point from someone who has or had one (though the Swamp Thang will probably sound vastly different from the original speakers that were used--P12R, right?). BTW...what speakers did these come with?
     
  16. dewman

    dewman Gold Supporting Member

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    It came with a P12R I believe...it was blown so I dropped in a broken in Celestion G12H30 and it was PERFECT for that amp.
     
  17. Mark Robinson

    Mark Robinson Member

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    Leon,
    You've come a long way from the crap we slapped together in my shop! But hey the price was right!
     
  18. slider313

    slider313 Silver Supporting Member

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    Leon, the original speaker used was a Jensen P12R; which turns to mud very quickly in one of these amps. My Martin 112 has a Celestion G12M blackback with the original 444 55hz cone. The DeArmond R15 has a WGS G12C for a more traditional Jensen type tone.
     
  19. Leonc

    Leonc Wild Gear Hearder Gold Supporting Member

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    Mike and Dewey, thanks for the info; will take under advisement ;)

    Mark - indeed, LOL! But that crap sounded good!! Actually, I still have the 4x10 and that cab still sounds great!
     
  20. Leonc

    Leonc Wild Gear Hearder Gold Supporting Member

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    More progress, cab is done except for front baffle and handle. Just tried it for the first time since getting the tolex on and I gotta say...this little @#$%er is off the hook badass. My hat is off do those guys at DeArmond. It appears that while they basically stole Leo's design, they sure figured out just the right places to tweak it.

    The cleans are big, full and chimey and the overdrive is muscular and thick but doesn't really get flubby. Every single guitar I've tried through it just sounds about as good as I've ever heard it sound. Hell...better...in some cases. I expected my SC and P90 guitars to sound good but the HB equipped ones are just wicked too.

    The amp cleans up from subtle pick attack changes and guitar volume changes as well as the best amps I've tried. Even the humbucker equipped guitars clean up amazingly well. The trem is deep and gorgeous but as kimock told me in a different post...the effect fades as you overdrive the amp.

    Lastly, the amp is a total pedal slut, so if you want to go for that "all clean" setup and get all your overdrive/distortion from pedals, it responds incredibly well.

    Anyway, enough babble and blather...

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