Module A-125 (VC Phaser) is a voltage controlled phase shifter.

Phase shifting can be controlled either manually or by voltage control. Other parameters which can be controlled are resonance (governing the depth of the comb filtering, and tonal color) and mix (the amount of the original signal which is added to the phase-shifted signal).

The A-125 is used to generate the typical phaser sound ("jet sound"). Due to the voltage control feature not only the usual LFO-controlled phasings but even ADSR-, random-, sequencer- or S / H-controlled phasings are possible.