Phase describes where a waveform is in its cycle at any moment, measured in degrees. On its own you do not really hear it, but the moment two copies of a similar sound are combined, their phase relationship decides whether they add up or fight each other. When they fight, you get phase cancellation: the sounds partly subtract, so you lose level and the result turns thin or hollow, most often in the low end.
The checks and fixes here are standard and work in any DAW. Phase is easiest to picture as a position in a repeating wave, and almost every real problem comes down to two related sounds that are slightly out of step with each other.
Phase describes where a waveform is in its cycle at a given moment. A sound is a wave of pressure that rises and falls in a repeating cycle, and phase is the position within that cycle, measured in degrees. One full cycle is 360 degrees, so halfway through the cycle is 180 degrees. Two waves that rise and fall together are in phase; one shifted so it rises while the other falls is out of phase.
On its own, for a single sound, phase is not something you hear directly. Your ears do not tell you that a wave happened to start a quarter of the way into its cycle rather than at the beginning. Phase only starts to matter when two related signals are combined, because then the thing that counts is how their cycles line up against each other.
The reason it matters is that combining, or summing, two waves adds them together moment by moment. When they are in phase, the peaks stack and the sound gets louder. When they are out of phase, a peak in one lines up with a trough in the other and they pull against each other. That simple fork, add up or cancel out, sits behind every phase problem in a mix.
Phase cancellation is what happens when two copies of a similar sound are out of phase and then combined: instead of adding up they partly subtract, so you lose level. It is the destructive side of the same summing that can also make a sound louder.
Picture two identical waves. Line them up exactly and they roughly double in strength. Now slide one back by half a cycle, 180 degrees, so its peaks fall where the other has troughs. Added together, they flatten toward silence. Perfectly opposite copies of the exact same signal cancel completely, but that is rare in practice. Real cancellation is usually partial and uneven, hitting some frequencies harder than others, so you rarely lose everything, just body and level.
The sound you are left with is thinner, hollower or weaker than either copy on its own. It shows up most in the low end. Long bass wavelengths are easy to knock out of step, and the low end is where a mix carries its weight, so losing it there is exactly what you feel as a track going thin or hollow. If a full sound turns weak the moment it is combined with another, cancellation is the usual reason.
Anything that puts two related but slightly different copies of a sound on top of each other. It is almost never one bad track on its own; it is two versions of the same sound that do not agree about where they are in the cycle. A handful of situations cause most of it.
| Cause | Why it cancels | What helps |
|---|---|---|
| Two mics on one source | The sound reaches each mic at a slightly different time, so the two tracks end up offset from each other. | Flip polarity on one, or nudge it in time until the two line up. |
| Layered or doubled samples | Stacking two similar sounds that were not built to sit together can push shared frequencies out of step. | Time-align them, or flip one and keep whichever version is fuller. |
| Stereo wideners | Many widen a sound by creating a difference between left and right that can collapse when the mix folds to mono. | Check in mono, ease off the amount, and keep the low end centred. |
| Short delays | A delayed copy summed back with the dry signal combs out a set of frequencies. | Run the delay on a send, or keep the dry and wet from stacking on the same part. |
| A flipped or miswired speaker | One cone pushes while the other pulls, so the two cancel in the air, mostly down low. | Check your cables and speaker wiring, and correct the reversed one. |
The thread running through all of these is the same: two versions of one sound arriving slightly apart in time, or inverted relative to each other. Stereo wideners are worth singling out, because width itself is built from differences between the two channels, and the very thing that makes a mix sound wide can partly cancel when it is folded to mono. That trade-off is covered in what stereo width is.
Sum the mix to mono and listen for anything that loses level or goes thin, then fix the offender by flipping its polarity, nudging it in time, or watching a correlation meter. Checking comes first, because you cannot fix what you have not heard.
The quickest check is to sum to mono. Cancellation that hides in a stereo spread becomes obvious the moment the two channels are added into one, because that is exactly the operation that makes out-of-phase content disappear. Anything that gets quieter or hollow in mono has a phase issue worth looking at. A correlation meter puts a number on the same thing: it reads how alike the two channels are, from +1 when they match, through 0, down to -1 when they are opposite. Readings that sit in the negative are a warning.
There are three fixes worth reaching for, in order of how surgical they are. The first is to flip polarity on one track. Most channel strips have a polarity button, and on two mics on one source, flipping one can bring the low end straight back; try it both ways and keep whichever sounds fuller. The second is to time-align or nudge: if the two tracks are offset because the sound reached them at different moments, slide one until they line up, which fixes the cause rather than the symptom. The third is to keep the low end mono, since cancellation bites hardest down low. Summing the lowest content to the centre keeps the foundation solid and clear, and it is the same habit that keeps a mix from turning muddy.
A polarity flip inverts the whole signal at once, turning every peak into a trough and every trough into a peak, which people often call a 180 degree flip. A phase shift is a delay in time, and because a fixed delay is a different fraction of the cycle for every frequency, it shifts each frequency by a different amount. So the polarity button is a blunt tool. It can rescue a lot, but it will not perfectly line up two tracks that are out of step because of timing. The two are closely related, and the words get used loosely, but knowing the difference tells you when to flip and when to nudge.
We do not sell a phase tool, and this page is not a quiet pitch for one. But phase problems are far easier to avoid than to chase down, and they are easiest to avoid when the source is clean to begin with. The Collection is our three instruments together, ARGISH, SILT and REHEAT, with three separate licence keys. Each one generates its own coherent stereo image as it plays, with the two sides moving together rather than fighting, so you start with clean, phase-coherent source sounds instead of cancellation you have to fix after the fact. ARGISH is a self-playing drone synth, SILT is a tape-loop instrument, and REHEAT writes acid lines. Every one ships as AU, VST3, AAX and a standalone app on macOS, signed and notarized, and a VST3 on Windows.
You can hear one free in your browser first, no install and no account, then decide.
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