The short answer
When several people sing or play the same line together, no two of them are ever perfectly in time or perfectly in tune. Those tiny differences, one voice a hair early, another drifting a touch sharp, are exactly what makes a group sound bigger and richer than any single performer. A chorus effect fakes that on one voice. It makes a few copies of your signal, nudges each one a little late and a little out of tune, and mixes them back in under the original.
You feed it a dry signal, a single clean voice, and it hands back a wet one that sounds doubled, thickened, like an ensemble standing where one person stood. A small amount gives you a subtle, produced sheen, the kind of quiet doubling you hear on a lot of polished vocals. Push it further and it opens into a lush, watery swirl. Either way the trick is the same: several nearly identical copies, none of them quite lining up.
Why copies thicken a sound
A chorus builds its copies out of two simple ingredients: a short delay and a slow detune. It starts by holding a copy of your signal back by a short amount, roughly 10 to 30 milliseconds. That is too quick to hear as a distinct echo; instead the copy just sits right on top of the original, like a second singer crowded up against the first.
Then comes the part that makes it a chorus rather than a plain doubled track. The effect slowly moves that delay time up and down with an LFO, a low, sub-audible control wave you never hear directly. Moving the point a copy is read from while it plays bends its pitch, the way a tape machine that cannot hold speed does: a touch sharp as the delay shortens, a touch flat as it lengthens, back and forth forever, and exactly in tune at the two moments the delay turns around. That gentle, wandering pitch wobble is the detune. No other voice is added. Stack a couple of these slightly late, slowly detuning copies of your own voice against it and your ear stops hearing copies at all. Kept small, the detune stays inside the range your hearing fuses into one source, so it hears several near-identical performers, which is the ensemble.
Reading the picture left to right is the same as hearing it over time. On the left the copies are almost in step, so the blend is nearly one clean wave. As the LFO stretches the delays, the copies slide out of phase and the blend thins; as it squeezes them back, they fall into step and the blend swells again. That constant, gentle coming and going is precisely what separates a rich chorus from a lifeless stack of identical tracks.
The controls that shape a chorus
Almost every chorus, in hardware or software, exposes the same small set of controls. The two most important ones, Rate and Depth, are really just the speed and the size of that internal LFO.
- Rate. How many times a second the LFO swings the delay back and forth. Slow rates, well under one cycle a second, give a gentle drift; faster rates start to sound like an obvious wobble.
- Depth. How far the delay is allowed to swing on each trip. Neither Depth nor Rate on its own sets how far out of tune the copies go. The detune comes from how fast the delay is moving, which is both of them together: double either one and the copies wander twice as far off pitch. A little of both is a subtle shimmer; a lot is the seasick, watery character people picture when they hear the word chorus, and if it makes you queasy, the delay is moving too fast.
- Mix. How much of the wet, copied signal you blend in against the untouched dry one. Low mix keeps your original voice clearly in front with a hint of thickness behind it; high mix pushes the swirl forward until it becomes the sound.
- Delay. The base delay of the copies before the LFO starts moving it. Around 10 to 25 milliseconds is the sweet spot where copies read as doubling rather than as an echo. This is part of the effect's sound, not a lag on your own monitoring.
From subtle doubling to a lush swirl
Chorus lives on a dial between two very different results, and where you land is mostly about dose. Keep the mix low and the depth modest and you get doubling: a discreet thickening that makes a thin voice sound fuller and more produced without ever announcing itself as an effect. This is the setting that flatters speech and lead vocals, because the words stay clear and only the body changes.
Turn the depth and mix up and the same machine becomes an obvious, shimmering swirl, the lush, underwater texture that defines a lot of classic clean guitar and dreamy synth tones. Nothing about the mechanism changed; you simply let the detuned copies get louder and wander further, so the ear now hears the movement as the point rather than as a quiet finish. Learning to move smoothly along that line, from a whisper of thickness to a full swirl, is most of what there is to know about using a chorus well.
Chorus versus a flanger
Chorus has a close cousin that trips people up: the flanger. Both blend a signal with a delayed, LFO-swept copy of itself, so on paper they look almost identical. The difference is the length of the delay, and it changes the whole character.
A flanger uses a much shorter delay, on the order of a single millisecond up to ten, usually with feedback that feeds the copy back into itself. Summing a signal with a copy that close creates a comb filter, a row of evenly spaced notches in the tone, and sweeping the delay sweeps those notches to make the metallic jet-plane whoosh a flanger is known for. A chorus uses a longer delay and does not lean on that comb. Its longer offset and gentle detune are aimed at a different goal entirely: not a sweeping whoosh, but the sense of several voices at once. Put simply, a flanger is about the moving notches, and a chorus is about the ensemble.
Chorus in Patchd
In Patchd, chorus is one node in the Studio voice-fx rack, sitting in the same picker as reverb, delay, and the rest of the effects. You add it to a channel like any other DSP node and dial it in with the controls above: Rate for the LFO speed, Depth for how far the delay swings, Mix for how much of the swirl you blend in, and Delay for the base offset of the doubled copy. The LFO is not a separate module you route around; it lives inside the node, and its Rate and Depth are how you meet it.
The node ships tuned by default for subtle vocal doubling, so a fresh chorus makes a voice sound fuller and more finished rather than obviously processed. A Double mode leans into that produced, barely-there thickening, and a lusher Chorus mode opens it up toward the watery swirl for when you want the effect out front. For most speech a low mix, around 15% to 25%, is plenty. Because the real-time engine runs over the low-overhead Windows audio paths, adding a chorus costs only single-digit milliseconds of engine-internal latency at a small ASIO buffer, so you can monitor yourself live while the copies do their work.
The takeaway
Chorus is the ensemble effect: it blends your voice with a few copies that are slightly delayed and slowly detuned by an internal LFO, so one voice sounds like several. Rate and Depth set how fast and how far those copies drift, Mix sets how much of them you hear, and the dose is what carries you from a discreet, produced doubling to a lush, watery swirl. Keep it subtle on speech and lean into it for music and character.
Patchd is a Windows audio mixer in open beta with a full effects rack on every channel and a Studio voice-fx rack that includes chorus among its modulation nodes. If you want a mixer that can thicken a single voice into an ensemble in real time, join the waitlist and get notified when it ships. The Studio tier is $5.99 a month, $39.99 a year, or $119.99 once for a lifetime license, and the real-time engine is identical on both tiers.