The Transposer effect shifts the pitch of the audio signal by the amount set by the Semitones and Cents knobs. Pitch can be shifted up to one octave up or down. The Transposer features two programs: Monophonic and Polyphonic.
MonophonicThe Monophonic program is optimized for monophonic ("one note at a time") audio. It features a Formant knob which shifts the formant of the sound. Pitch shifting sounds most natural if the formant is shifted in the other direction (eg. if pitch is shifted up 2 semitones the formant should go down two semitones).
Transposer window ('Monophonic')
PolyphonicThe Polyphonic program is optimized for polyphonic audio. It is extremely CPU efficient while still producing good sounds. Part of the efficiency comes from a limited headroom, which is where the Level knob comes in. If the light above it lights up the audio signal is clipped and you should turn the Level knob down a bit. This typically won't happen, but it may if the signal has been amplified by other effects. If a track has been recorded at a very low level you can turn up the Level knob to maximize sound quality.
Transposer window ('Polyphonic')
Note: the Transposer only works if delay compensation is available. In short this means it doesn't work 'live' using Soft Monitoring.