The three modulation effects share similarities, but understanding their differences will help you choose the right swoosh for your sound.
Dream pop, shoegaze, psych rock, jazz, grunge… modulation effects have found their way into almost every genre. Walk into any music store and you’ll find walls of pedals that promise to add movement, depth and texture to your sound. Among the most popular are chorus, flanger and phaser pedals—all members of the modulation family. Though these effects share similarities and often complement each other, their differences can be subtle enough to leave players scratching their heads about which one they actually need to achieve the sound they’re after.
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All three modulation effects work by changing your signal, creating that sense of motion and adding harmonic richness. What sets them apart is which part of the signal they manipulate and how they go about it.
Chorus
What it sounds like: Lush, shimmering, and thick, chorus makes a single instrument sound like multiple players performing in unison (like a chorus!). Its effect ranges from a subtle double that adds body to your tone, through to the obvious warble that you’d hear in ‘80s pop or more modern dream pop, bedroom pop and jangle pop.
How it works: Chorus split your signal into two paths. One remains dry and untouched, while the other is delayed by a very short time (typically 20-30 milliseconds) and modulated with a low-frequency oscillator (LFO). This LFO continuously varies the delay time, creating subtle pitch variations that mimic the natural imperfections of multiple instruments playing together. When these signals are mixed back together, your brain perceives multiple sound sources.
What you can do: Depth and rate controls allow you to dial in your sound, from shimmering to kind of seasick wobble. Slower rates with moderate depth create that classic ’80s chorus shimmer, and faster rates with shallow depth add subtle animation without drawing attention. Many modern chorus pedals also include tone or EQ controls to shape the character of the effect, and some offer stereo outputs for an even wider soundscape.
Where you’ll hear it: Chorus defined the sound of ’80s pop and rock, but its versatility spans across Prince, Metallica, the Cure, and Nirvana. Dream pop and shoegaze artists rely heavily on chorus for creating expansive, ethereal soundscapes, while jazz players favour it for adding warmth to clean tones. The effect became genre-specific by the mid-’90s, thriving particularly in indie and shoegaze circles while grunge and hip-hop dominated mainstream rock.
Classic uses: Andy Summers’ sparkling arpeggios in The Police’s “Message in a Bottle” are textbook chorus. Kurt Cobain used chorus extensively throughout Nirvana’s catalogue, particularly on “Come As You Are.” Jazz players like Pat Metheny have made chorus an integral part of their signature sound, using it to add warmth and dimension to clean tones. Steve Lacy, a noted Prince fan, uses chorus liberally across his work, crafting effortless tunes that swirl in a cloud of the effect.
Phaser
What it sounds like: Phaser is all about the swoosh and the swirl. This modulation creates a sweeping, jet-plane-like effect that’s immediately recognisable. Less obvious than flanger but more pronounced than chorus, phaser adds movement through a series of peaks and troughs in the frequency spectrum. The result is that classic “whooshing” sound that can be subtle and musical or wildly psychedelic.
How it works: Phasers work by splitting your signal and sending one path through a series of all-pass filters (typically 4, 6, 8, or 12 stages). These filters shift the phase relationship of certain frequencies without affecting their amplitude. When this phase-shifted signal is mixed back with the original, some frequencies cancel out while others are reinforced, creating those characteristic notches. An LFO sweeps these notches up and down the frequency spectrum, producing the swooshing effect.
What you can do: Rate controls the speed of the sweep. Slow rates create subtle, organic movement while faster settings produce that pronounced swirl. Depth (sometimes called intensity or resonance) controls how dramatic the effect is by adjusting the feedback amount. More stages generally mean a deeper, more complex sound with more notches in the frequency spectrum. Some phasers offer additional controls for manual filter positioning or envelope following.
Where you’ll hear it: Phaser has been used across psychedelic rock, funk, pop and alternative music. Funk players particularly love phaser for adding heft and gleam to choppy chord patterns, as demonstrated by Nile Rodgers with Chic and Carlos Alomar on David Bowie’s mid-to-late ’70s records. For heavier music, phaser helps thicken riffs and make solos pop. Eddie Van Halen relied heavily on phaser for his “brown sound,” while Brian May used it for Queen’s live performances. The effect exploded in mainstream popularity during the 1970s, defining the sound of psychedelia before finding its place in funk, reggae and electronic music throughout the ’80s and beyond.
Classic uses: Eddie Van Halen’s “Eruption” showcases phaser at its most explosive. David Gilmour used phaser to create the signature sound on Pink Floyd’s “Breathe.” Ernie Isley combined phaser with fuzz to create perhaps the most oft-imitated ’70s funk lead tone of all time on “That Lady”. Tame Impala’s Kevin Parker has made phaser a cornerstone of his psychedelic production style, creating the swirling, dreamy textures that defined his earlier work, Innerspeaker and Lonerism.
Flanger
What it sounds like: Dramatic, metallic and jet-like, flanger is the most aggressive member of the modulation family. Where chorus sounds like multiple instruments and phaser creates smooth sweeps, flanger delivers an intense, whooshing effect with a distinctive hollow quality. The effect has a strong, tunnel-like resonance that cuts through a mix with authority.
How it works: Flanger operates similarly to chorus but with much shorter delay times (typically 1-5 milliseconds) and adds a crucial element: feedback. The delayed signal is fed back into itself, creating a series of harmonic peaks and troughs called a comb filter. This feedback is what gives flanger its characteristic metallic, resonant quality. An LFO modulates the delay time, causing those peaks and troughs to sweep up and down the frequency spectrum, creating the jet-plane effect.
What you can do: Speed controls how fast the sweep moves, while depth determines how wide the frequency sweep travels. The real character comes from the feedback (or regeneration) control—more feedback creates those dramatic, resonant peaks that define classic flanger sounds. Some flangers offer manual control to freeze the sweep at specific points, creating fixed comb-filter tones. Through-zero flanging (found on higher-end units) allows the delayed signal to cross through zero delay time, creating an even more dramatic effect.
Where you’ll hear it: Flanging came into style in the late 1960s when psychedelically-inclined artists like The Beatles, Jimi Hendrix and The Small Faces used it to add trippiness to their recordings. The effect has long been essential in rock and metal, heard in everything from Heart’s “Barracuda” to Tool’s “46 & 2”. From Bowie to Van Halen, flanger became a mainstay of popular music during the 1970s and ’80s. The sweeping effect is especially useful for creating atmospheric, spacey sounds in psychedelic rock and progressive rock, while digital flangers are suitable for modern genres like metal, pop and electronic.
Classic uses: “Barracuda” by Heart features one of the most recognisable flanged guitar riffs in rock history. The intro to “Ain’t Talkin’ ‘Bout Love” by Van Halen demonstrates flanger’s ability to add aggression to power chords. Jimi Hendrix used flanging to create psychedelic, otherworldly textures on “Axis: Bold as Love,” though this was likely a studio effect rather than a pedal. More subtly, countless bass players have used flanger to add movement and presence without overwhelming the low end. Pink Floyd’s David Gilmour applied flanger to both rhythm and lead tracks on his 1978 solo album with gorgeous results.
Choosing your modulation
The question isn’t really which modulation effect is “best” but rather which achieves what you’re after. Chorus excels at adding width and dimension without drawing attention to itself—perfect for clean tones that need body. Phaser sits in the middle ground, offering movement that’s noticeable but musical, making it versatile for rhythm and lead work across funk, rock and psychedelic genres. Flanger makes a statement, adding more drama and intensity that works brilliantly for big riffs or experimental soundscapes.
Many players keep all three on their boards, using them in different contexts or even stacking them for more complex textures. Your ears are the best guide—experiment with each effect at different settings to discover which movements and textures inspire your playing.
