I looked at the ETI Hyper Fuzz in a post, and again in another post. As mentioned this shares a lot with the Crowther Prunes and Custard.
The original ETI Hyper Fuzz had a complicated, or at least confusing to me, input section. I showed it someone else, who said “hey that’s clever”. It was still over my head and involved a lot more parts. I replaced the three transistors of the original circuit with a single transistor common emitter amp. This worked. Taking a second look I thought maybe that transistor could go and single op-amp would do the job as input buffer?
I mocked this up in the simulator, and it seems to work well. Try it out for yourself here.
I tested with clipping diodes in the first stage and without. The gain control seems to bunch all of the interesting changes into the last 10% of the range. I’m guessing this can be spread out with a A or C taper pot.
The wave form on the left represents the input signal. The center wave shows the output of the first op-amp, imagine this as the input, and the wave form on the right shows the output of the second op-amp, this would be the output.
Here is a picture of the first mode, with the gain all the way down. The input is a 500mV sine wave. The output shows some mild distortion.
Here the gain is up almost to full.
The wave form looks like wave folding, with a sort of bat wing shape. The pot morphs from the wave form in the first image to this shape. Maybe there is a range of useful sounds in there?
Lets simulate the mode switch. The mode switch is an on/off/on type. In the first mode it connects the output to the 330K at the top of the diode ladder. In the middle position it is open.
The output, with the gain low, looks a lot like the first mode with the gain low.
With the gain up we get an extreme version of the same wave form. Is that crossover distortion?
The third mode connects the output stage to the middle of the diode ladder.
This interesting. Looks like an octave/frequency doubling or tripling? hard to tell but it does looks different from the other modes. This mode works through some interesting changes across the gain pot.
