DigiTech WHAMMY User Manual page 11

Detune - This group of Presets creates a copy of your input signal, slightly shifts the pitch of
the copied signal and mixes it back with the original signal. As the treadle is rocked back and
forth, the level of this detuned signal is changed. With the pedal in the toe up position, only the
original dry signal is heard. As the pedal is rocked forward, the detuned signal is mixed with the
dry signal. The Detune Presets include:
Detune
Presets
Shallow - The copied signal is shifted slightly out of tune from the
original pitch.
Deep - The copied signal is shifted substantially out of tune from
the input signal.
User's Guide