In General
"The Boss Phaser PH-2, featuring 12 stage phase shift circuits, allows stronger effect than any other phase shifting unit. Two completely different phase effects are optional just by changing the position of the knob. Adopting antilogarithm circuit in the filter the PH-2 gives smooth modulation effect. The indicator lights up when the effect is one so that you can at a glance tell whether the effect is on or off." (Manual Boss)
Details
"Rate: This knob controls the rate of the phase shift effect. At the fully clockwise position, phase effect of 100ms is obtained. As you rotate the knob counterclockwise, the rate slows down up to 14s.
Depth: The knob controls the depth of phase shift effect. Rotating this clockwise deepens the effect.
Resonance: This knob controls the amount of feed back signal. Rotation this clockwise emphasizes the phase shift effect, therefore the created sound will be more unusual.
Mode selector: In the mode I position, phase sound, deeply swelling from high frequency to low, is obtained. The mode II is a phase sound with sharp phase shifting effect." (Manual Boss)