Adrenochrome Fuzz

[Fancy Lime]

Hey folks,

heres a simple little fuzz I built primarily for bass. Never tried it with guitar but should sound just as good. Very 60's. Spirit in the Sky, anyone? But at low gains and without the gates engaged you get some nice fat milder fuzz tones. I accidentally found out that reverse biased transistors not only work in a fuzz, they also sound awesome. Well, they sound different at least. Much less gain, so great for the old 60's type fuzz circuits that basically just tried to squeeze every last little bit of gain out of low-gain transistors. I just put them in the wrong way by accident and later found out that Jack Orman has an article about that and there also seem to be some commercial designs that use this "trick", although the schematics floating around the interwebs never quite seem to agree whether or not they are indeed reverse biased. Anyway, here it is:



I call it Adrenochrome because it can sound quite psychedelic. (For reference see Aldous Huxley: The Doors of Perception.) The Gate pot is basically a (mis-)bias knob on Q3. It makes the whole thing sound quite sickly and brittle. The BAT41 diode gate introduces heavy takeover distortion but kills the quite intense hiss at higher gains. At low gains you can get away without a gate but reverse biased 2222s seem to be quite noisy as a general rule of thumb. At least I could not get them to be quiet by themselves.

Please let me know if I accidentally "stole" someones ideas or if there are existing designs that are very similar that I did not credit because I do not know about them.

Cheers and have fun with it,
Andy


EDIT: I forgot to mention that I have one power supply with which this thing does not work at all. Makes no sound. It works with a battery (current draw ~75µA) and with all my other power supplies (including a VS 1-Spot). No idea why.

[Barracuda]

Looks good dude! Nice simple schematic with plenty of shaping options, like it!

[Hatredman]

Any chance of photos and a sound clip?


--
Scarlett Johansson uses a Burst Box with her Telecaster.

[Fancy Lime]

I'll try to record a few samples over the weekend. The box that this sits in at the moment isn't much to look at; my first attempt at enclosure etching. I'll snap some pics and pot them anyway, so others don't feel as bad when their first etch does not come out as they wanted.

Andy

[patrick398]

Following this with a great deal of interest, would love to hear some clips!

[Fancy Lime]

Here some pics of my build. I called mine the "bombus bombus" before finding out that that name is taken for a fuzz (actually just Bombus but same same) and renaming it Adrenochrome. The design was my first attempt at etching. I used NaOH and it did not go well. Mostly because the toner dissolved rather quickly. I the also etched the back plate, just for testing, with ferric chloride. Much better but still not good. Third time was the charm, but that was for this thing:
http://www.diystompboxes.com/smfforum/index.php?topic=118341.0

I also have some audio samples now. Any idea anyone how to best post those?

Please excuse the messy interior, that has done in quite a hurry. Still, no guts, no glory, so heres the pics.







Cheers,
Andy

[mac]

I also have some audio samples now. Any idea anyone how to best post those?

I upload schematics and clips in my gallery here.

mac

[Fancy Lime]

Thanks for the hint mac!

Here's the sample:

http://www.aronnelson.com/DIYFiles/up/Adrenochrome.mp3

Bass is a Cort B4 fretless with the active electronics removed. Best 400€ I ever pent on an instrument. Sound mediocre with the on-board preamp but if you take that out and use it passive it is absolutely fantastic. Signal chain: Bass -> Adrenochrome Fuzz -> focusrite scarlett 2i4 -> Ardour4. No effects, compression or eq-ing in the software.

First riff is dry, then I go through some different setting that I like. Please excuse the playing quality.

Cheers,
Andy

[Fancy Lime]

One more thing,

When recording the sound samples I realized that I almost always use the thing at full gain with the tone switch in neutral. So if I were to build another one of these I would probably leave out the gain pot and tone switch plus C10 and C11. I'd might also skip the gate switches and D1 and D2 and just leave the adjustable gate on all the time. I like to have as few controls as possible. Unfortunately that means I always end up with many controls...

Cheers,
Andy