Chorus vs Flanger vs Phaser: Differences and When to Use Each

What is the difference between chorus, flanger and phaser?

The difference is the processing element. Chorus and flanger are both delay effects with a modulated delay time, separated mainly by how long that delay is, while a phaser shifts phase with all-pass filters and never delays the whole signal.

iZotope puts typical chorus delays at 15-35 ms and flanger delays at a much shorter 1-5 ms, and notes that phasers use an all-pass filter circuit to change the phase relationship among frequencies instead.^[1] That one design choice explains everything you hear: chorus wobbles in pitch, flanger whooshes with a strong metallic resonance, and phaser swirls more gently.

How does a chorus effect work?

A chorus mixes the dry signal with one or more copies on a delay line whose time is constantly moved by an LFO. Because the delay time keeps changing, the copy drifts slightly sharp and flat, which the ear reads as extra players who are almost, but not quite, in tune.

Image-Line describes its Fruity Chorus as an effect created by the slight detuning of one or more delayed copies of the input, similar to a choir of voices. The plugin's Delay control runs from 0 to 30 ms, and Depth sweeps the delay between the Delay value and Delay plus Depth.^[2] Depth sets how far the pitch wobbles, Rate sets how fast, and a stereo spread setting modulates left and right differently for width.

Chorus moved from studio trick to stompbox through Roland. BOSS says Roland first built chorus into the Jazz Chorus amplifier in 1975, and in June 1976 BOSS announced its first effects pedal, the CE-1 Chorus Ensemble, initially aimed at keyboard players.^[3] Synth players know the sound from the Juno line; TAL-Chorus-LX, for example, is built to emulate the Juno 60 chorus.^[4] A deeper look at that plugin is in our TAL-Chorus-LX breakdown.

How does a flanger work, and why does it sound like a jet?

A flanger mixes the signal with a copy delayed by only a few milliseconds, too short to hear as a separate sound. The two versions cancel at a series of frequencies, and as the LFO moves the delay, that series of notches sweeps up and down the spectrum.

Sound on Sound notes that the processing element in a flanger is a short delay, typically under 20 ms, and that the cancellations repeat further up the spectrum from the first notch.^[5] The math is simple: at an equal mix, a 1 ms delay cancels 500 Hz, 1.5 kHz, 2.5 kHz and so on, one notch every 1 kHz. Halve the delay to 0.5 ms and the notches spread twice as far apart. That regular spacing is the comb filter that makes flanging sound pitched and hollow.

Feedback is the other ingredient. Sending part of the output back into the delay sharpens the peaks between the notches, and iZotope notes that with flangers, feedback accentuates the notches and resonances, giving the harsh, metallic timbre the effect is known for.^[1] In FL Studio's Fruity Flanger, Delay runs from 0 to 20 ms, Rate from 0 to 5 Hz and Feedback from 0 to 100%.^[6]

How does a phaser work without a delay line?

A phaser splits the signal, runs one path through a chain of all-pass filters, and mixes the paths back together. An all-pass filter lets every frequency through at the same level but shifts phase by different amounts at different frequencies, so the recombined signal cancels at a few points.

Sound on Sound explains that classic guitar phasers typically use a four-stage all-pass filter, which produces two moving notches, while bigger designs go further: the MXR Phase 100 has 10 stages and five notches.^[5] Every two stages add one notch.

Unlike a flanger's comb, those notches are not evenly spaced. Image-Line's Fruity Phaser manual puts it this way: various frequencies are delayed by different amounts, causing peaks and troughs that are not spaced evenly. It also notes that old stompbox phasers usually have 4 or 6 stages, while the plugin can run up to 23.^[7] Fewer notches mean a gentler, more vocal-sounding sweep, which is why a phaser often sits better under a lead than a flanger does.

• Stages More stages add more notches and a denser, deeper sweep. Four stages is the classic, subtle setting.
• Feedback (resonance) Emphasizes the peaks between notches for a more vocal, whistling tone. Keep it low on full mixes.
• Rate Slow rates of 0.1-0.5 Hz give a pad-like drift; fast rates of 3-6 Hz lean toward a rotary or vibrato feel.
• Sweep range Sets how far the notches travel. Narrow ranges stay subtle; full-range sweeps become the main event.

Chorus, flanger or phaser on vocals, synths and guitars?

Chorus is the safest choice for width, flanger is an ear-candy effect you automate in and out, and phaser adds movement without taking over. iZotope describes flangers as transitional effects and momentary ear candy, with phasers used when more nuance is needed.^[1]

Vocals

Put chorus on a send and high-pass the return so the low end of the voice stays mono and solid. For flanger on vocals, keep the mix low and automate it to a phrase or a single word; using flanger on vocals subtly covers the settings. If you want a natural doubled sound rather than an effect, real layered takes beat any chorus, as shown in how to layer vocals for a chorus effect.

Synths and guitars

On pads, chorus hides the static quality of a single oscillator, and a slow phaser adds movement across an eight-bar loop. BOSS suggests keeping chorus rate and depth at no more than 12 o'clock on clean guitar to stay clear and ethereal.^[3] On bass, keep the sub dry: modulation below about 150 Hz smears the low end and weakens it in mono.

What settings should you start with?

Start subtle and push only until the effect is audible in the full mix, not in solo. These values are starting points for common plugin controls; adjust them by ear.

1. Name the goal
   Width or thickness points to chorus, an obvious sweep or transition points to flanger, and gentle motion points to phaser.
2. Start on a send
   Put the effect 100% wet on a return so you can EQ it and blend it without touching the dry track.
3. Sync or slow the rate
   Sync flanger and phaser sweeps to 1, 2 or 4 bars so the movement lands with the arrangement instead of drifting against it.
4. Filter the return
   High-pass the return around 150-300 Hz so the low end stays mono and clean.
5. Check mono
   Sum to mono. If the part gets thin or hollow, reduce stereo spread, depth or mix until it holds.

Why does chorus sound thin in mono, and other common mistakes

A wide stereo chorus often modulates the left and right sides in opposite directions. Summed to mono, those two copies partly cancel each other, and the part can lose body or pick up a hollow, flanged tone. Phone speakers and many club systems are effectively mono, so always check.

• Too much depth Heavy chorus on a lead vocal pulls the pitch audibly out of tune. If tuning suddenly sounds off, lower depth before you touch the tuning plugin.
• Modulating the low end Chorus, flanger or phaser on a full-range bass weakens the fundamental. Split the bass and modulate only the upper band.
• Flanger left on all song A constant jet sweep stops being exciting after a few bars. Automate the mix for transitions, drops and single phrases.
• Stacking all three Chorus into flanger into phaser turns into mush. Pick one main modulation effect per part.

Want tools to test all three? The best free modulation plugins covers chorus, phaser and flanger options side by side. Longer delay times take you out of modulation territory and into echoes, which is the subject of the sibling article on delay types.