Tube Preamp, NYC Muff enclosure



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Tube Preamp, NYC Muff enclosure

Postby Adamadamadam » Mon Jul 30, 2018 9:15 pm

Q: Holy shit! Where have you been?
A: http://ilovefuzz.com/viewtopic.php?f=42&t=60417

So my first fuzz pedal was an NYC Big Muff. I got it as part of a trade and wasn't blown away by the sound, but it's a well-known circuit with hundreds of dedicated mods and the chassis is enormous compared to the size of the electronics. It's the stompbox I cut my teeth on and after several years, a mess of wires, lifted traces, and a re-house, it's completely non-functional. Which is fine. I held onto the original enclosure for no particular reason.

Naturally, I decided to build a high-voltage tube preamp into it (I already had the transformers from something else that never happened, which were at least half the overall cost). It's basically a single-channel Alembic F-2B with a james tone-stack. The plate voltage for the 12a_7 is around 340v. The noise floor is a bit higher than I'd like, but I haven't played around with some of the more exotic dual-triodes with a different MU for each side. I've only tried ax7s and au7s, and the u doesn't provide enough gain. I've been able to saturate the tube with higher-output 'buckers, but with vintage style strat pups it stays clean. I put the volume before the second gain stage, so there's some flexibility there. Either way, it can pummel the front end of whatever it's plugged into.

More looking to show-off than sell, but shoot me a message if you're interested. I don't really have much use for it.

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Last edited by Adamadamadam on Mon Jul 30, 2018 11:57 pm, edited 1 time in total.
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Re: Tube Preamp, NYC Muff enclosure

Postby crochambeau » Mon Jul 30, 2018 10:24 pm

Nice job stuffing!

340 volts on the anode is pretty steep for a 12AX7, I wonder if that is contributing to the noise floor? I like to park mine in the 160-220 range.
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Re: Tube Preamp, NYC Muff enclosure

Postby Adamadamadam » Mon Jul 30, 2018 10:44 pm

It's possible, but I think it has more to do with having to ignore every audio-wiring best-practice in order to get the circuit to fit. My understanding is that the original Alembic also had a comically high B+, though I can't find a schematic at the moment. It's not awful: think SD1 at full tilt, but I expect more from myself.
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Re: Tube Preamp, NYC Muff enclosure

Postby BetterOffShred » Mon Jul 30, 2018 10:44 pm

Toroidal transformer = sex.

Cool build. Did you chopstick your wiring dress to see if you have any lays that contribute to noise ?
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Re: Tube Preamp, NYC Muff enclosure

Postby Adamadamadam » Thu Aug 02, 2018 9:12 pm

BetterOffShred wrote:Cool build. Did you chopstick your wiring dress to see if you have any lays that contribute to noise ?


Unfortunately I don't have a lot of leeway there. I suspect the problem stems from the molex-type connection that connects the pots to the eyelet board. It makes it much easier to crack open and work on, but I don't have a ton of say in where the wires end up when closed.
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Re: Tube Preamp, NYC Muff enclosure

Postby ibarakishi » Fri Aug 24, 2018 8:10 am

any demos of this?
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