Changes

''Phasers'' use a (often variable) number of all-pass filters (called ''stages'') to reverse the phase of certain frequencies, combining this phase-altered signal with the original signal to create nulls throughout the frequency spectrum. An LFO modulates how the stages operate and at what frequencies the nulls occur, sweeping them back and forth. Phasers can also use feedback on the phase-altered line to alter the make the nulls wider and less sharp. Some additionally have a mix parameter to determine the proportion of the dry (unprocessed) signal vs. the phase-altered signal.

* MXR Phase 90

The most important thing to be aware of is the ''manual'' control - properly setting this parameter is crucial to getting the sound you want.

* Boss BF-2

* Boss BF-3

Some choruses may combine both techniques.

* Boss CE-1

* Boss CE-2

Many devices attempt to simulate the Leslie Rotary Speaker enclosure, which rotated a speaker on a motor to provide a shimmery sound by cyclicly slightly pitch-shifting the audible sound via the doppler effect. While these devices commonly utilize the same techniques as phasers, flangers, chorus, or some combination of those, I want to mention them separately in case you didn't realize that. Also, more modern simulations may be more faithful to the acoustic principles of the original Leslie.

* Univox Uni-vibe