Modulation effects alter a signal in a cyclical manner over time: volume, pitch, phase, or delay vary continuously. They have quickly become essential for guitar, keyboards, and audio production.
Modulation effects were among the first to emerge in the mid-20th century. As early as the 1940s and 1950s, electronic tremolo and vibrato (volume modulation for the former and pitch modulation for the latter) appeared, along with rotating speaker effects (Leslie), which were popularized in the 1940s with Hammond organs.
The tremolo effects in the Fender Vibrolux, and Twin Reverb amplifiers helped create the “pulsating” and “mesmerizing” sound of surf music. Meanwhile, the Leslie simultaneously offered mechanical vibrato, chorus, and Doppler effects. It wasn’t until the late 1960s—1968 to be precise—for a modulation effects pedal to make its debut: the famous Uni-Vibe, used by Jimi Hendrix, among others.
The flanging effect also debuted in the late 1960s, initially in the studio, through tape-reel manipulation (the engineer slowed the tape down by holding a finger on the supply reel). The Beatles and Pink Floyd used this technique extensively. In 1975, Roland released its legendary Jazz Chorus JC-120, equipped—as its name suggests—with a chorus circuit. The following year, Boss incorporated the circuit into a pedal and called it the CE-1. That same year, the New York-based giant Electro-Harmonix unveiled its famous Electric Mistress.
In the 1980s, with the emergence of the first digital systems, the chorus effect literally became the sound of an era. It was heard to excess in genres like New Wave, Pop, FM Rock (remember the heavily chorus-laden guitar sounds of bands like Mötley Crüe, RAT, and Extreme), and Fusion. Artists like Mick Mars, Andy Summers, and The Police epitomize this trend.
Modulation multi-effects were born during this era with the arrival on the market of products such as the Eventide H3000, Roland GP-8 and Boss SE-70, digital processors that allowed users to run multiple modulation effects simultaneously, save presets, or process audio in stereo. These digital systems produced cleaner, wider sounds with a “hi-fi” quality that was prized at the time.
Since the 1990s, another trend has shaped the market: the analog revival. Two main approaches stand out: a return to analog with vintage circuits and analog BBDs (bucket-brigade delays), and digital modeling that recreates classic effects using algorithms. Numerous brands are competing in these two segments, with new players such as Kernom and Walrus Audio emerging alongside giants like MXR, Electro-Harmonix, and Universal Audio.
There are seven common modulation effects: chorus, flanger, phaser, tremolo, vibrato, rotating speaker, and “Vibe.” (based on the Uni-Vibe). Advanced effects such as detuning, micro-pitch, and ring modulation can also be considered modulation effects. In this roundup, we’ll highlight ten multi-effect modulation pedals so you can choose the one that suits you best.
