Cheap DIY Distortion and Compressor and Fuzz kits

[DrNomis_44]

Thanks Doc, posting voltages would be a great help.

I've checked all the voltages and they seem okay, but that doesn't mean they are correct. Both the B-E voltages are at a fraction under 0.3V, however the collector voltages indicate either saturated or cut-off. With these transistors I might have t try a resistance wheel to Q1 base to find the right value to get Q2 collector at 4.5V

You could also try replacing the collector resistor (typically an 8k2) for the second transistor with a 10k trimpot, this will allow you to easily set the collector voltage to around 4.5V, the smaller value resistor (330 ohms or 470 ohms) can then be increased to 1k to increase the output level a bit.

As a sidenote, the collector voltage on the second transistor plays a big part in determining the sound you get out of a Fuzz Face, if it is around 4.5V, the result is a smooth squarewave sounding fuzz tone, below this the Fuzz Face tends to sound a bit sputter, which some guitarists tend to like, above 4.5V, the Fuzz Face gets really smooth, but you also lose a bit of sustain. most of the commercially manufactured Fuzz Faces tend to be biased so that they clip the signal asymmetrically, I seem to remember playing around with the Fuzz Face circuit, after breadboarding it, and managed to take some pics of the waveforms I saw on my Oscilloscope, I think I still have the pics on one of the slave HDDs in my studio PC, I'll post them here as reference.


I managed to find this one, if your Fuzz Face build is working and biasing correctly, you should see a waveform like this on the first transistor's collector, the waveform on the second transistor's collector should look like an inverted and more sharply clipped version of this waveform (assuming that you've set the Fuzz control to maximum):




Here's an interesting article about the technology of the Fuzz Face:

http://www.geofex.com/article_folder...ace/fffram.htm