1960 CF Martin + wanted

dklsplace

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Like I said jp, my original intent was to turn this around & make some quick money, but after plugging in & playing through it, I was astounded! Maybe when these things begin to break the 20k mark I'd consider selling. 8)

I just sent an email to Tonequest asking if they knew any of the history regarding these being built by Allen instead of Rowe.
 

capnjuan

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Solid design, competent workmanship, and premium transformers. No one said the Holy Grail, if/when found, had to have Leo Fender's fingerprints on it.
 

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David from Tonequest responded already. He said he had heard the reference to Allen Organ, but confirmed with them awhile back that they didn't build any of the amps. I'm going to crack it open again & take some pics...don't recall if that info was on a label, or the schematic.
 

dklsplace

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Seems the only place I can remember seeing the reference to Allen Organ building these was the Flying Vintage article in my first post. No labels in the amp, & no mention of another company on the original schematic & instruction sheet. Bah! :|
 

capnjuan

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If any of you want another chance at the rarest of rare Martin / Tonequest amps, start reaching for your checkbooks: Martin 1X12 eBay listing Like DKLs; as highly regarded as they come. VGC model sold several months ago +/- $2,500, lesser copy shortly thereafter not as much.

Martin112.jpg
 
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Hi,
I'm new here, and have done some research on this. The circuit of the Martin 112/DeArmond R15 is basically a Fender 5e3 Tweed Delux with some pot and cap changes... and a huge OT. The schematic is available on the CD in the new Groove Tubes book - the only entry under Martin. Tonequest bought one and liked it so much that they, blueprinted it, and cloned it (their Clarksdale amp), sending the transformers to Mercury Magnetics. Mercury lists these (DE-AR-OT, DE-AR-PT) under "other transformers" (down at the bottom where Felix is walking back and forth). I ordered a set to check them out, but asked Paul for a larger PT. He suggested the FBFVL-PM, the lower voltage Vibrolux option. The Clarksdale is built with the Sozo "mustard" caps and an Eminence Wizard speaker, which they liked best. Other transformers: I believe Paul said that the primary was 6.7K making it suitable for running 6l6s/7591s (ToneQuest suggests running 6L6s with a 5AR4 in theirs for more headroom). Antique Electronic Supply has replacements made by Hammond, I believe, and Allen Amps has some made by Heyboer, both less expensive than the Mercuries.
 

capnjuan

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Hi Jnick1947, welcome, and thank you for your comments. Given the integrity of the design and workmanship, not hard to believe that the Martin / Tonequest / Clarksdales must have astonishing tone. Thanks again. cj
 

capnjuan

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Interesting; EPs 9097/9098/9099 must be the red wax-potted packages of resistors and / or caps, must help damp noise. Cathode-biased providing some Class A tone attributes but still Class A/B operation, no negative feedback, but 25uf caps on the preamp cathode a la Fender and Gibson promoting a woodier, bassier sound.

Tremolo tied in ahead of the PI and not at the 6V6 grid resistors...and using a Varistor. Modest voltages on the preamp plates of 150VDC / 175VDC and 300VDC on the driver like high voltage on tthe 7247 driver in the later Guild amps. But it's the iron in the output transformer that makes the difference.

cj
 

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Just found a martin r25-t schemo, PM me if you don't have it. A very large jpeg, btw.
 

capnjuan

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Hi steve; I'd like one. Brown? I'm thinking semi-sweet dark .... It's the output transformers; somebody spent the extra money. Tempted to try and find a project Gibbie and strap on high-grade output iron ... sort of the same thing; pairs of 12AX7s followed by 6V6s except something more than the stock reverb-size OTs.
 
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Looking at the 112T schematic, only one pot (the intensity pot) has a taper specified (left handed), which according to my old catalogs, means a normal log taper. Does anyone know the taper of the volume and tone pots?
 

capnjuan

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Hi Jnick; you'll have to wait for Don - as far as I know, he's the only one who owns one of these. cj
 

dklsplace

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Yeah, sorry. I did receive your email but haven't gotten to it yet. Don't let me forget!
 

dklsplace

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jnick1947 said:
Looking at the 112T schematic, only one pot (the intensity pot) has a taper specified (left handed), which according to my old catalogs, means a normal log taper. Does anyone know the taper of the volume and tone pots?

Hey John, just checked my pots. Tone & channel two volume pot are definitely audio taper pots. Volume on channel one was giving me some funky stuff on the meter (perhaps why I don't use it?). Need to dig for my original email....didn't you ask me something more specific about these?
 
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Thanks for that.
The channels are biased very differrently, as one can see in the voltage chart on the schematic, and the tremolo channel has a much smaller coupling cap to help remove the modulating frequency. The way the pots are wired they drop out more of the low frequencies the more they are turned down. The non tremolo model 112 has a 12AY7, instead, with a common 820 Ohm cathode resistor. The two volume pots are also interactive. I have begun building a version of the 112 that will have switchable 12AY7 and 5879 pre amps with switchable supply voltages (suitable for harp, or, guitar) and Power Scaling for the output section. Power Scaling (developed by Kevin O'connor of London Power) does what attenuators are supposed to do - allows the amp to be "cranked" at ANY volume. However, it does this by reducing the voltages on the output and driver sections simultaneously with voltage regulators. Stay tuned.
 
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