There are only a few guitarists out there who can claim to be true masters of the Whammy pedal in the sense of incorporating it into their moment-to-moment playing, as opposed to using it as a whacky effect. Tom Morello and Johnny Greenwood are certainly among them. Trey is right up there, having really made this one of his signature effects in 3.0 (though it’s been in the rig for much longer).
The Whammy pedal has two sides; a harmonizer and a pitch bender. Trey most frequently uses the pitch bender, which allows the user to bend pitches using the expression pedal to various degrees up or down. Trey almost always uses this feature in its middle position, which is 2 half steps down. So by depressing the expression pedal, the guitar tone sweeps down two half steps, eg, from an Bb to an Ab. Then as your sweep the pedal back up, the tone returns to the original note. In early 3.0, Trey was experimenting with this sound, dubbed the “Whale,” quite a bit. Mr. Miner wrote about it here, and an example from the June 11, 2010 “Light” is below:
Back in the “Excalibur” days, when Trey would hold the guitar above his head and swing it up and down, he’d use the full octave or 2 octave bend features to give the illusion that swinging the guitar was causing the wild pitch bends.
The harmonizer adds a second pitch to whatever pitch the user is inputting, so a player can have a harmony following along in 3rds, 4ths, 5ths, etc. Trey uses this occasionally deep in ambient or noise jams to very strange and mesmerizing effect. Here’s a rare example of him using it in a Type I jam, during the 8/15/11 Undermind at UIC Pavilion in Chicago:
Trey also likes to use this pedal as an octave pedal — either up or down. The Whammy II can do this, but other pedals are better at “tracking” octaves (Electro-Harmonix POG, Mu-Tron Octave Divider), so they sound more natural and less effect-like when doing it. The Whammy will distort and create occasional digital errors/artifacts when tracking octaves, which makes it sound almost like an analog synth. Listen below.
Subsequent reissues of the Whammy II went back to the style of the original Whammy I, which requires the user to bend down and twist a knob to select modes. Trey prefers this version in part because modes are selectable by tapping a footswitch.