Vibrato is a simple concept. If you play a stringed instrument, a woodwind, a horn, or sing you understand that it is a technique by which you pulse a note above and below the technically “correct” pitch. Joe Bonamassa, Itzhak Perlman, Renée Fleming, and David Sanborn all understand the expressive use of vibrato.
While vibrato is the manipulation of pitch, tremolo is the manipulation of volume. Unfortunately, this simple distinction between effects has been widely misunderstood by electric guitarists for decades, thanks, in part, to Leo Fender. Fender initially got it right, naming his first tremolo amp the Tremoluxe, but early on he began misnaming the tremolo channels in many amps “Vibrato.” He transferred this confusion to his invention of the classic “whammy bar” bridge for the Fender Stratocaster. To this day, the Fender Company incorrectly refers to the arm of the bridge as a tremolo arm, when in fact, the bridge offers no control over volume — just pitch. None of this kept tremolo from catching on as an effect — surf bands and country guitarists jumped on board; Duane Eddy sold millions of records. Vibrato wasn't so lucky.
Outside of Lonnie Mack, few famous guitarists raced to embrace the electronic fluctuation of pitch. “Rivers of Avalon,” by the Red Hot Chili Peppers was one of the rare appearances of this effect in modern times. Despite this lack of interest, Boss released its VB-2 Vibrato pedal in 1982, soon responding to the resulting indifference by pulling it from the market. Lately, electronically produced vibrato has been finally finding a fan base among guitarists; enough so that Boss has reissued the VB-2 in their new Waza form as the VB-2W, while Earthquaker Devices, T.C. Electronic, and others have also launched vibrato pedals. More on these later, but first: how does electronic vibrato work?
As with modulation pedals like chorus and flanging, low frequency oscillation is involved. Low-frequency oscillation (LFO) is an electronic signal, usually below 20 Hz, that remains unheard while creating a rhythmic pulse or sweep. In a vibrato pedal, it's used to sweep the pitch up and down. Vibrato pedal controls include at the very least, a control for Depth, determining how far the pitch is swept, and Rate, adjusting how fast the pitch is swept.
Pedal makers may approach this effect in various ways. Earthquaker Devices’ Aqueduct completely removes the original signal. In effects like this, a little vibrato can go a long way. Greater depths may require Dramamine pills for nausea, though wide sweeps can be quite interesting and less queasy at faster rates. The Aqueduct offers a range of usable, musical effects by offering envelope control, and a switching option that permits you to momentarily engage and disengage extreme settings for maximum dramatic effect. The T.C. Electronic Shaker Vibrato’s direct signal seems always present to some extent, which allows more extreme settings without seasickness. Boss’ VB-2W offers both the original sound of their pioneering pedal and the new Waza Craft “custom” setting, which makes the sound deeper, darker, and more intense. It and the Shaker also allow momentary engagement. These pedals can be used to simulate finger or bridge vibrato and for a plethora of new atmospheric and emotive sounds.
Guitar effects can be as subject to the vagaries of fashion as the latest hemlines. The chorus effect we liberally employed in the Eighties now sounds embarrassing to some of us. Tremolo was popular on introduction, and then largely disappeared, only to resurface with Americana. Fuzz ruled the Sixties before hibernating until the Nineties. It would appear that vibrato is having its moment, offering a welcome new modulation color, so feel free to ride the wave, be it sine or square.