It's a sound heard on thousands of records, featured on some of the most popular amplifiers ever made. It's also one of the most incorrectly labeled effect in all of music. The Tremolo effect has been a part of popular music before overdrive was a thing and can be heard prominently to this day on several genres of modern music, from rockabilly to roots and more. It's a very distinct sound with a vintage feel and an interesting history of being mislabeled time and time again. Today, we're going to break down what exactly tremolo is and recount its tangled past with vibrato.
The Evolution Of Tremolo
Simply put, tremolo is a rhythmic shift in dynamics, not unlike turning a volume pot up and down in a consistent manner on a guitar or amp. The sound is unforgettable once it becomes familiar. Vibrato on the other hand -- the effect tremolo is often mislabeled as -- is a shift in pitch. When a player bends a note up and down or uses a "tremolo" bar, its vibrato.
The first stand-alone effects device made for guitar was a tremolo effect, and we have to go all the way back to the late 1940s to see them start showing up. The DeArmond Tremolo Unit was used by people like Muddy Waters all the way up to Billy Gibbons, and creates its sound by interrupting the signal flow of the guitar by means of electrolytic fluid within the enclosure. While this worked, the fluid dried up eventually so you’d have to open it up and replace the fluid from time to time. Tremolo is now produced through a circuit in an amp or an effects device. This circuit automatically turns the signal volume up and down. Amps with tremolo may also use several different kinds of technology to achieve the effect, including low frequency oscillators, bias modulation and light dependent resisters.
While modern units have expanded well beyond the simple controls found on vintage pedals and amps, the tremolo effect is still mainly controlled by two settings: rate and depth (also sometimes labeled as speed and intensity on some amps). Rate controls how quickly the volume changes and depth controls the intensity of the effect. Creedence Clearwater Revival’s Born on the Bayou has a tremolo intro with an depth that is just deep enough to provide movement to the chords without sounding choppy. Compare that to the intro to Tommy James’ Crimson & Clover which has a more intense, choppier sound due to the increased depth of the effect.
Tremolo or Vibrato?
The history of misuse between the two terms can be dated way back to the late 1800s when patents filed with the US Patent and Trademark Office began using them incorrectly. While there weren’t any electric guitars back then, these early patents were describing tremolo and vibrato devices intended for instruments such as the violin, viola and cello.
Things got further convoluted between vibrato and tremolo in the 1950s when amp and guitar makers continued the tradition of mislabeling the two effects. When Leo Fender introduced the Stratocaster in 1954, it came equipped with the signature Synchronized Tremolo system, a bridge design that allowed the strings pitch to modulate by manipulating the bar, in other words, a vibrato effect. Meanwhile, amps containing a true tremolo circuit that modulated volume would regularly label this built-in effect as vibrato. For example, Fender's legendary Deluxe Reverb and Twin Reverb amps featured two channels, a normal channel and a "vibrato" channel which actually added tremolo, not vibrato.
Because of this long history of manufacturers using the terms incorrectly, plenty of players use tremolo and vibrato interchangeably, adding to the confusion. While both effects are two of electric guitar’s most signature sounds, they are distinctly different, so remember: Vibrato is a change in pitch, tremolo is a change in volume!
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