The earliest version of the infamous HP was actually a dual silicon transistor circuit. It also had a few addons and a few big cap fifferncies compared to the later Ge/Si version. Not sure how it sounds but I guess some of might be interested to to try this one out.
The 2N3565 transistors had a quite wide gain range between 100-600 hfe so socketing might be a wise idea. I would start out withs 2N3904 or 2N5088s, just mind the pinout.
Schematic is avaiable HERE.
Have anyone heard of this one? This is a a super rare distortion unit with clean blend and octave up. There is no sound demos online but the lucky few ones that have played one says it is quite a wild sounding circuit.
Schematic is a avaiable at Deadend Fx.
Based on EHX Small Clone but with lots of mods and useful addons.
Schematic is avaiable HERE.
*Update 231112*
Layout is corrected since Erubi spotted some errors
This is a monster!
It is based on the schematic by Lectric Fx which includes a recovery stage with internal trimpots to set the output volume.Schematic is avaiable HERE.
This circuit is quite infamous for being quite noisy with oscillator bleedthrough just as for most Bit Crushers. ,And to make things worse, this one has a built in fuzz circuit that amplifies noise even more. Hopefully, the separate ground connections for the fuzz/output buffer section and the the oscillator will tame some noise.
After Josh Homme revealed one of his secret weapons, the small Peavy Decade amp, prices on those sky rocketed tenfold. Deadend Fx just released thier Dekandent project which is based on the preamp section. Not sure how close you'll get to the QOTSA tone but it is at least a piece of the puzzle.
Schematic is avaiable HERE
Our ukrainian friend Zzoyds modified version of Masaru Kubuta Allies Fuzz.
No schematic for this one but HERE is a very useful link!
Here are his description about it:
...we have Masaru Kubota Allies Fuzz.so i built it with germanium transistors + added a third stage for normal volume.What I want to say about this Ge beast; you can use it like a fuzz, you can use it like a Ge booster,which working with every overdrive, every fuzzes!How's the fuzz pot working? Very strange, when you turn to left you get less gain and more highs,when turn to right, more gain and more mids. I really like this one! Using with overdrives, you get another sound!
Don't forget to check out his other design, Black Velvet Fuzz.
Tim Escobedo's take on the rare Harmonic Percolator. Simple with no mojo parts in sight.
This is it for, now. Covid restrictions were lifted here today so I'm going to take a break and try to live a normal life for a while ;-). But here is a project of the 70s version of EHX Clone Theory which should keep you occupied for a while. An onboard voltage doubler is included followed by a 15v voltage regulator for the required power supply. The only addon in the audio path compared to the vintage units is a booster stage and volume trim before the output to cure the slight volume drop when the circuit is engaged.
Schematic is avaiable HERE.
Requested a few times so here it is. It is based on Boss CE-2 but it has a few useful addons and mods. Schematic is avaiable HERE.
