Kay Fuzztone FZ-1 has an octave "DOWN" !!!

[MartyMart]

I was playing this last night at a Jam session and discovered the following :
Using my Strat, on neck pickup with tone rolled off, when I play a very accurate
5th using the "A" and "D" strings or "E" and "A" strings I got a perfect octave below !!!
So an octave under bottom "E" on the gtr is available.
If you strike low E,  then add the fifth from the A string, the octave under appears
very clearly and the "Fifth" kind of dissapears .... 
I was blown away and have not noticed that before !!

It helps if you "pluck" them together, sort of "Mark Knopfler MTV Style"

Caveats :
1) There are three of these FZ-1 schems around and I chose to use the version
which has a 250K output pot, without the 100k to ground just before it.

2) I have "played" with the notch frequency set up with this effect, using the 10k/22k
and a 6n8 cap pre-output.

3) Q1/Q2 are 2N4401's Q3/Q4 are OC140 Ge's (NPN hfe around 125)

4) Diodes are 1x 1N90 Ge and 1x 1N90Ge plus 1x 1N4148 in parallel

These things will have a bearing on the "tone/octave" I guess I just got lucky

Marty.

[Bernardduur]

That's cool; I've never heard of a fuzz with an octave down function.....

Maybe a new market?

[petemoore]

  A 1 transistor 'Electra Distortion' circuit does interesting octdown between E and A on the E string mostly.

[Mark Hammer]

When JC Maillet (the Viva Analog guy who uses a chord as his handle when he posts) dropped in for a visit a few summers back, we were fooling around with octave units, including one of his.  The topic came around about the manner in which ring-modulation type side-band products came out, depending on how one was playing.  The poster-child for this byproduct is the Dan Armstrong Green Ringer, whose rather spare design places it, for many players, somewhere in between an octave-up fuzz and ring-modulator.

This sideband by-product piqued JC's interest and curiosity, and he started working on the math.  Formulae with Greek letters are much more his domain than mine, so I will simply say that, yes, almost ANY octave-up fuzz that uses a phase-splitter approach to full-wave rectification (see below) WILL produce sideband content when used in a certain manner.  I suspect most folks using an octave-up fuzz would report a certain "rubber band" quality to them when notes are slowly bent.

Since such sideband products include both sum AND difference, it is not at all unreasonable or surprising to suggest that one would hear the note frequency minus itself (i.e., freq/2 = one octave down) once in a while.  Of course, several conditions are required for this to happen.  First, the note has to be picked in the optimum manner.  Second, the rest of the signal path (including speakers) has to permit that sideband to be heard.

What is a phase-splitter approach to full-wave rectification?  The key here is any octave-up fuzz where you see a transistor using equal value resistors from collector to V+ and emitter to gnd, and the separate collector and emitter outputs combined together.  For instance, in the Green Ringer, you can see the second transistor has equal-value resistors and both collector *and* emitter outputs.  In the Fender Blender, the comparable stage is 3 transistors into the circuit where equal-value 8.2k resistors can be seen on the emitter and collector, and the two outputs summed through identical cap/resistor/diode networks.  You'll see something similar in all the Univox Superfuzz and Shin-Ei Fuzz-wah units that produce an octave up.

Again, let's emphasize that these are first and foremost octave-UP units.  The fact that they are capable, under some very special circumstances, of producing something that can sound like an octave down is purely fortuitous.  A nice accident, but an accident nonetheless.

[MartyMart]

Thanks for that Mark, so it may/maynot happen or be as apparent, on a second build
of the same circuit, or even others ?
My build/gtr/tone settings/amp are all contributing to this "octave down" !!

That's a very "happy" accident

Marty.

[Mark Hammer]

Well, it's not an accident in the sense that you'd NEVER get it again with another octave-up pedal.  Rather, since the design of the pedal is not directed at producing an octave down, you'll get it sometimes but not always.  Heck, even octave-up notes are not always a given in such designs but if one had to guesstimate, I'd say that octave-up tones are often obtainable 90% of the time when you try to get them (within choice-of-note constraints), where octave-down tones are obtainable maybe 5% of the time (15% for Jeff Beck, but 5% for us mere mortals) within the same constraints.  I'm sure you've found that the likelihood of obtaining low tones rests pretty solidly in the fingers than in any component choice.

[MartyMart]

Yeah, you have to be "very" accurate, as soon as you just "look" at another
note/ringing string ............. the effect is lost !!

I'm not a "great" player, but I'm accurate enough ! 

M.