Get the Guitar Sound You Want: Cheat Sheet for Modulation Effects

Posted by John Tyler Kent on Feb 9, 2016 08:00 AM

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A great way to add an extra bit of flair to your playing is the intermittent use of modulation effects. Modulation effects are essentially time based, similar to delays and echos. What sets them apart is that various forms of alteration, such as detuning, oscillation, and modulation, are applied at different rates and intensities to create unique sounds and textures. The resulting sounds can range from something as simple and subtle as a light chorus to something as wacky and aggressive as a ring modulator.


When someone who's new to the world of audio effects describes an "underwater" sort of sound, chances are that he or she is referring to a chorus effect. Chorus is an effect that imitates the slight differences in pitch and timing that occur when multiple musicians (or a "chorus" of performers) perform the same part in unison. This effect can exist in mono or stereo, and any number of altered voices, as well as varied levels of depth, speed, and intensity, can be used to create different choruses.

Kurt Cobain frequently made use of different chorus effects throughout Nirvana's breakthrough album, Nevermind.

Flanger and phaser

Flangers and phasers are frequently grouped together because of their very similar sounds and processes. A flanger uses a signal that's delayed by a small amount (usually 10 to 20 seconds; this duration will often modulate over time) and plays it back into itself. The resulting signal will have infinite equally spaced notches throughout its frequency spectrum. (This is frequently described as "comb filtering," as the resulting graph of the signal looks like a comb with its teeth pointing downward.)

Phasers function similarly, but will often use a series of "all-pass filters" to create a set number of notches in the frequency spectrum. The difference in sound is subtle: flangers are often described as a more airplane-like effect, while phasers sound more vocal- or wah-like and work better in a more psychedelic context.

Eddie Van Halen is notorious for using flangers and phasers to add character to his guitar work. You can hear a fairly subtle but unmistakable flanger in the song "Unchained" from Van Halen's 1981 album, Unchained.


A vibrato pedal will simply bring what you play into it in and out of tune at whatever rate you set it at. This can be used to create anything from a slow, slight waver in pitch to a much faster and more shaken kind of sound. Momentarily removing the responsibility of vibrato from your fingers gives you the opportunity to create unique vibratoed phrases that would have been otherwise very difficult or impossible to achieve.

Guitarist Pete Thorn gives a review and demonstration of the Diamond Vibrato pedal.


The Uni-Vibe is something of a tribute to the Leslie speaker cabinet. This cabinet contained speakers that would rotate at either a slow setting (identified as "chorale") or a faster setting (identified as "tremolo"). This sound is most commonly associated with the Hammond organ, though its popularity amongst guitar players eventually led to the creation of the Uni-Vibe pedal as well as the Rotovibe, which is essentually a Uni-Vibe with variable speed via an expression pedal. Uni-Vibe and Rotovibe pedals include a control that switches between a chorus-based sound or a more vibrato-based sound.

"Bridge of Sighs" by Robin Trower is a frequently referenced example of the Uni-Vibe sound.


Tremolo is a fairly simple effect that can go a long way. It's just a series of volume swells and drops that happen at whatever rate you choose. Most pedals also give you the options to determine the depth of the tremolo and how smooth the volume changes are. Tremolo is a unique modulation in that there are no detuning or changing harmonics happening within the effect, which makes it a very practical and cooperative effect to use. Tremolo pedals can often be used with a tap tempo or expression pedal for added timing control.

The song "Bones" by Radiohead is a unique example of using an expression pedal to alter the tremolo's rate.

Ring modulator

Ring modulators combine your input signal with the signal from an internal oscillator and outputs only the sum and difference frequencies. The resulting harmonics are typically very odd sounding, making this a difficult effect to control. This effect is commonly used to get bizarre synth textures and digital oddities out of the guitar, though when mixed carefully and sparingly it can be used on occasion to add unique color and interesting harmonic content as well.

Known to be a guitarist who embraces ugly tones with open arms, Omar Rodriguez-Lopez of The Mars Volta often takes advantage of the abrasive sound of a ring modulator.


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As a performing musician, John Tyler Kent has played with a wide variety of artists for all kinds of audiences, from small clubs across the country to international music festivals. In addition to his work as a performer, Tyler has working experience in marketing, production, and composition.

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