Octave Fuzz, needs a critique

[soggybag]

I'm trying to add an extra stage to the Kay Fuzz to separate the Octave and the original signal and blend the two with Pot 2. I'm guessing this may work as is.

I'm also assuming that I can bias and supply an input to both Q2 and Q5 from the output of Q1.

Looks like Q1 is set to maximum gain, should probably add a gain control to Q5.

The tone control of the Kay looks funky. Maybe this needs to be removed or modified. Then again, I read a few posts claim this added character to the original Kay Fuzz.

Please let me know if anyone sees any glaring errors. I haven't built this yet. Will fill in the values later. I'm open to suggestions.

[petemoore]

  The collector and bases will need to be DC biased, wires between Q1C, and the two bases [as shown] will keep them all at a common voltage. Adding DC blocking capacitors between active stages allow bias resistors to establish individual DC biases on the separate transistor pins.

[Mark Hammer]

Interesting.  Many of the various octave fuzzes will use the same phase-splitter arrangement, and tack on clipping diodes after (e.g., Fender Blender, Superfuzz, Tone Machine), essentially fuzzing the octave, and adding even more harmonic content, that you might not want.  The separation of octave and clipping into blendable components is a nice idea.

I would suggest the following, however, to "optimize" it (and I leave it to you to judge if that goal is achieved via these suggestions).

The clipped path could probably benefit from some optional treble cut.  In a sense, you'd like to be able to dial in low end growl but still have it be heard.  Or, flipping it around, you'd like to be able to have a respectable throaty growl have some octave added to it in blendable fashion.  Keeping the tone of the two paths a little more distinct will make the blending a more rewarding exercise, I think, and lead to a more "vocal" sound.

I also have to add that I'm just not getting the logic underlying your output control.  Are you sure that's drawn the way you want?

[liquids]

Yeah, all I see is a lo-fi 'blend' control, and a single knob tone control, no volume...but maybe you were considering that a given?

C8 should be unnecessary.

[soggybag]

Thanks for the reply. Here's a schematic of the original Kay F-1.

The tone control looks a little strange, that's just what was there. I'm thinking I may change this. The 100K resistor to ground at the output could easily be a pot to create a volume control.

The real question here is biasing Q5 and Q2 from the output of Q1 in my schematic. Which I'll post again below.


Seems that Q2 is biased from the output of Q1 in the original. My real question is whether I can bias both Q2 and Q5 from the output of Q1. If I understand the BJT, the base takes in a small amount of current, but not much. So I think should work, though it might require adjusting R4?

Seem that adding a cap between Q1c and Q2b and Q5b would require that I include a couple extra resistors to supply a bias current since the cap would block the DC coming from Q1.

[soggybag]

bump