Heathkit TA-28 Fuzz Booster

The Heathkit TA-28 "Fuzz Booster" is made from a badly biased Complimentary Feedback or Sziklai Pair, followed by a passive filter/attenuator section. The original 2 knob enclosure included a hardwired output cable, just like the first Maestro Fuzz Tones. Note that the power supply is a single AA battery, just like the FZ-1A. The actual circuit is quite different than the Maestro units. This topology is more like the 2TEF (Fuzz Face) in that it can also make a nice clean boost if the resistor values are properly set.

The 100µF cap ensures the elimination of ac negative feedback across the 2.7k resistor, and thus maximum voltage gain for the signal.

The output is split between the 22nF/1k high pass filter, and the 6k8/1k attenuator. Assuming the next stage's input impedance is ≥1M, the 1k and 50k pot in parallel makes for a ≈980Ω load and this sets the -3dB cutoff for the high pass at ≈7.3kHz. This network is simply tacked onto the output of the voltage amplifier, and thus can be either ditched or replaced by the filter of your choice without disturbing the active section.