yet another FF clone :)

[brett]

VERY cool circuit....

I've been going over this thing with the signal generator and 'scope and there's some really interesting things here.  One is that not only is the input signal compressed, the compression happens at the cost of significant gain.  That might explain the apparent success of Q1s with high hFE, set up for more gain than would normally be considered good in a fuzz face.

With a sine wave of 100mV (p-p) at 1kHz on the input side of the diode, only 8mV appeared on the other side of the diode.  That's a loss of 12x or a little over 10 dB.  With 10mV input, almost 2mV gets through (5x loss), indicating good compression.  I used 100mV and 10mV because they represent a firmly, freshly picked note and a soft or decayed note, respectively.

The other thing that is noticable in the scope trace is how asymetric the signal becomes after the diode.  Kinda like what you'd get from a tubescreamer or bluesbreaker with a mild amount of drive.  Looks really interesting.

Actually, I'm dying to use this pedal, but it's 11pm and the missus is in bed, so I guess it'll have to wait until morning.  

For the record, these measurements were done with a Q1 = 2N2369A with hFE= 75 and a 33k collector resistor and Q2 = BD139 with hFE=100 and a 1k fuzz pot.

cheers

[brett]

Hi.  Built it using regular FF-style transistors (hFE=70 and 120).  Fuzz was modest unless turned way up.  That loss of gain of about 5 x across the diode makes me think that maybe a Q1 transistor with hFE about 5x70 might be best in this circuit.  Interestingly, the input impedance of this fuzz is very high (50k for a large signal, 100k with a small signal).  This probably explains some of its differences in tone from a regular fuzz face.

This circuit is definately worth experimenting on.

cheers