octave-up

In fuzz pedals it can appear as a controllable effect, as in the Foxx Tone Machine's warm, thick fuzz with a controllable octave-up effect¹, or as an overtone added by a 1970s-style circuit². Some designs generate it via a full-wave rectifier and band-pass filter, producing sounds reminiscent of a vintage octa-fuzz³. Others let players blend the octave-up voice with the dry signal or a sub-octave, as in the MXR Slash Octave Fuzz⁴ and the Maestro Brassmaster⁵. Pitch shifters like the TC Electronic Sub 'N' Up offer individual blend controls for dry signal, octave-up, and two sub-octaves⁶.