Tube Preamp, NYC Muff enclosure

Do-it-yourself pedal building

Moderator: Ghost Hip

Forum rules
The DIY forum is for personal projects (things that are not for sale, not in production), info sharing, peer to peer assistance. No backdoor spamming (DIY posts that are actually advertisements for your business). No clones of in-production pedals. If you have concerns or questions, feel free to PM admin. Thanks so much!
Post Reply
User avatar
Adamadamadam
committed
committed
Posts: 114
Joined: Thu Apr 14, 2016 11:12 am
Location: The Land of Enchantment

Tube Preamp, NYC Muff enclosure

Post by Adamadamadam »

Q: Holy shit! Where have you been?
A: 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.

Image

Image

Image

Image

Image

Image
Last edited by Adamadamadam on Mon Jul 30, 2018 11:57 pm, edited 1 time in total.
User avatar
crochambeau
IAMILF
IAMILF
Posts: 2204
Joined: Mon Jul 20, 2015 12:49 pm
Location: Cascadia
Contact:

Re: Tube Preamp, NYC Muff enclosure

Post by crochambeau »

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.
User avatar
Adamadamadam
committed
committed
Posts: 114
Joined: Thu Apr 14, 2016 11:12 am
Location: The Land of Enchantment

Re: Tube Preamp, NYC Muff enclosure

Post by Adamadamadam »

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.
User avatar
BetterOffShred
IAMILFFAMOUS
IAMILFFAMOUS
Posts: 3412
Joined: Thu Aug 17, 2017 2:01 pm

Re: Tube Preamp, NYC Muff enclosure

Post by BetterOffShred »

Toroidal transformer = sex.

Cool build. Did you chopstick your wiring dress to see if you have any lays that contribute to noise ?
User avatar
Adamadamadam
committed
committed
Posts: 114
Joined: Thu Apr 14, 2016 11:12 am
Location: The Land of Enchantment

Re: Tube Preamp, NYC Muff enclosure

Post by Adamadamadam »

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.
User avatar
ibarakishi
experienced
experienced
Posts: 968
Joined: Fri Dec 16, 2016 10:31 am
Location: Thailand
Contact:

Re: Tube Preamp, NYC Muff enclosure

Post by ibarakishi »

any demos of this?
good deals/trades/business with: JonnyAngle, rdw102, crochambeau, worra, $harkToootth, Olin, fuzzonaut, friendship, ianmarks, digi2t
Post Reply