Stomp boxes have been giving electric instrumentalists a sonic edge for many years. Three very popular effects used to paint shimmering aural landscapes are phase shifters, chorus pedals, and flangers. These three pedals are also commonly confused because they sound very similar. To learn the differences between them, it helps to have a basic knowledge of how they work, examples of their use in popular music, and of course, your very own stomp boxes to experiment with.
Phasers split the signal of your instrument into two exact copies, shift the phase of one copy, and then recombine the two as a single signal. As a result, notches (or particular frequency bands that are canceled out) are created, just like when you mismatch speaker wires in a home stereo unit. These notches are then swept through the entire frequency band, creating a rippling, Doppler-like effect in your sound.
Phase shifters are capable of creating subtle, submissive waves that don’t over-saturate your tone. There are scores of recordings with these effects, especially in classic rock. Check out Billy Joel’s piano sound on “Just the Way You Are” for a great example of tasty phaser use.
A flanger sounds similar to a phase shifter, but can have a much more dramatic effect on your tone. Like a phaser, the signal is split into two copies, then one of them is delayed in time very slightly, usually no more than 20 milliseconds. The delay time also changes at a constant rate, which can be manipulated with a knob.
The effect was first discovered in the studio, where two identical reel-to-reel tape machines with the same track on each were synched to start at the same time. The engineer then pressed his thumb against the “flange” of one to momentarily slow it down and take it out of synch. And hence, the flanger was born.
Flangers create a much more complex harmonic reaction in the signal than a phaser, resulting in a more saturated and dramatic sound. Listen to Eddie Van Halen’s opening riff on “Unchained” for a great example of the flanger’s jet plane-like effect.
A chorus pedal is very similar to a flanger and a phaser in that it creates two clones of the signal. The difference is that a chorus pedal uses a longer delay between the two signals, which creates a more subtle effect than a flanger or phase shifter. Chorus pedals are designed to mimic the wavering, space-evoking sound of a choir. Chorus pedals work really well in a stereo configuration, where the effect is produced through two widely spaced amplifiers. When standing between the two in a large room, it has a surreal 3D effect on the listeners’ ears.
For an example of a chorus pedal in action, listen to the guitar tone on Nirvana’s “Come as You Are.”