Having created implementations of the Fuzz Face and Rangemaster, my eye was caught by another vintage design – the Tonebender 3 knob. The Tonebender 2 knob is “just” a Fuzz Face with an extra gain stage in front but the Tonebender 3 knob is a completely different topology.
Again, the same arrangement for the -9v rail has been used, along with the buffered clean output. In all three cases, the effect output is also fully buffered. The clean buffer for driving the noise gate has a very high input impedance and so does not additionally affect the sound at all.
After all very this retro activity, I then decided to fast forward a few years to a pedal that was all the rage when I was a teenager: The ProCo Rat. The clipping arrangements of the Boss DS1 and the Tube Screamer abound in countless designs (indeed, the Tube Screamer topology is present in the Rat), but the use of the externally compensated (to limit the slew rate) LM308 opamp in the Rat is not an idea that has cropped up anywhere except Rat clones. The alterations I’ve made to the Rat circuit are a buffered Vref, a buffered output and a Moonlight tone control in place of the simple RC low pass tone control of the Rat.
That leaves me with a lot of pedal building to do before I can assess whether these designs can add some new elements to my rather large collection of distortion effects!