Three matched germanium transistors sit at the core, as in the original MKII. EarthQuaker adds a phase-corrected, buffered output, so pedals placed after the fuzz receive a strong, low-impedance signal. The output stage also gives more volume than the classic design, with unity gain around noon on Level.

Attack is the main control. Low settings give an amp-like distortion that follows picking strength. Turning it clockwise builds into heavy fuzz with long sustain. Rolling back the guitar volume cleans the sound up.

Like most classic fuzz circuits, Barrows has a low input impedance. The circuit works best with the guitar plugged straight into it, so place it first and keep buffered pedals after it. Switching is mechanical true bypass.