A nice simple octave-up fuzz

[Mark Hammer]

This is an older (circa 2001) Japanese schematic for what is essentially a reduced Superfuzz.  I forget where I found it.  I've posted the Superfuzz schematic below for comparison.  I built one and am quite pleased with it.

The most notable differences are that this one has a much simpler front end, based around a single FET.  It also omits the tone-control circuitry and the additional gain-recovery stage intended to make up for the passive signal loss via the tone control.  However, like many issues of the Superfuzz, it includes a trimmer to achieve optimum balance between the two complementary outputs of the phase splitter, and the more robust octaving that comes from that.

On mine, I installed a 10k pot between the clipping diode pair and ground, to adjust how much clipping is added to whatever the phase-splitting and recombing provides (and it does distort, even without diode help, just not quite as much).  Lowering the resistance provides harder clipping

Naturally, without the midscoop filter, the tone is essentially that of the non-scoop position.  Even with the germanium diodes, it has plenty of output, though more when the diode clipping is dialed back.  The octaving is pretty decent.  Certainly as good as the Mayer Octavia I made, and the Superfuzz I made and sold.

So, a simpler, more compact build with fewer parts and more than acceptable performance.  Mine is in a 1590B with gobs of room to spare.  The perf piece is 20 holes x 9.  I just used a standard unselected K30A for the front end, and matched Q3 and Q4 for hfe.  Maybe a GR is better for the front end, but this one is certainly good enough.

[aron]

How do these compare with the much more simpler op amp with inductor+diodes circuits? Is there lots of fuzz with this circuit?

[Mark Hammer]

Good question.  I haven't built things like the Bobtavia, though I had made a Tychobrahe clone some time back, and I may have made an Escobedo unit and I think one of Gus's Octave-up Sick boxes.   No Brassmaster.

It's not overly fuzzy, but is fuzzy enough.  Not Scrambler fuzzy, or Superfuzz sound-of-death fuzzy, but fuzzy.  Octaving kicks in decently above the 8th fret.

My sense is that units that use diodes to separate complementary halves, tend to impart a very slght difference due to the requirement that the signal first exceed the forward voltage of the diode.  It takes a few milliseconds until the plucked string meets the 500-600mv threshold imposed by a series diode, so the initial transient comes out just a tad different.  For me, the epitome of that nuanced difference can be found in the Hendrix nugget "One Rainy Wish", where the notes have a dreamier quality by virtue of having initial transients that seem compressed or even missing.

This unit, lacking those series diodes, does not have that nuance.  Naturally, as a phase-splitter-based circuit, you still get all those sideband products when you bend strings.  I'll see if I can get a sample up this weekend and let you be the judge.  I'll just end by saying that it's only a little more complex than a Green Ringer, yet gets a decent octave that normally might need a bigger circuit to achieve.