> f, 2f, 3f, 4f, 5f, 6f, 7f, 8f, 9f, 10f > Does this module actually do this? Yes. And its mostly done by waveshaping. Full wave rectifiers give you the doubling, and the rest is bizarre combinations of diodes and clipping circuits. Clever. And no I don't have a copy of the circuit. Tony www.oakleysound.com