Phase Alignment Checker

What is a phase alignment checker?

A phase alignment checker measures the stereo correlation between the left and right channels of your audio. Correlation ranges from −1 (perfectly out of phase — left and right are inverted) to +1 (perfectly in phase — mono playback is identical to stereo). Values near 0 mean the channels share little in common, often due to stereo widening effects, Haas delays, or polarity-inverted mics. Our free phase alignment checker reads your file, computes the average correlation, and warns you about phase cancellation that will hurt your mix on mono playback systems.

Why phase issues matter in mixing

Phase issues mixing problems are one of the most common silent killers of a good track. When your left and right channels are partially out of phase, the signal cancels itself out when summed to mono — bass disappears, vocals thin out, and the whole mix loses weight. Many listeners hear your music in mono: phone speakers, smart speakers, Bluetooth in mono mode, and car systems that sum channels. A phase alignment checker catches these problems before release so you can fix polarity, reduce stereo widening, or adjust mic placement.

How to read stereo correlation

A healthy mix reads between +0.5 and +1.0 on the correlation meter. Below +0.5 indicates widening that may compromise mono; below 0.2 is a red flag; a negative value means your channels are inverted and will cancel badly in mono. Use this phase alignment checker alongside your DAW's correlation meter — if you see low readings, solo individual elements to find the offender (typically a stereo widener, doubler, or a multi-mic'd source like drums).

Typical correlation values

How to fix phase cancellation

If your correlation is low or negative, identify the offending element by soloing tracks while watching a correlation meter. Common fixes: flip polarity on one channel of a stereo mic pair, reduce the depth on a stereo widener or Haas delays, replace phase-shift widenens with short delays (5–15 ms), and always check your drum overheads and room mics for phase alignment before mixing.

Frequently asked questions about phase and mono compatibility

What is a good phase correlation for a mix?

Between +0.5 and +1.0 is safe in mono. Readings from +0.8 to +1.0 are tight and mono-safe, and +0.5 to +0.8 still has healthy width while summing safely. Below +0.5 some elements begin thinning in mono, below +0.2 you hear real cancellation, and a negative value means the left and right channels are polarity-inverted.

What correlation is too low?

Below +0.2 is the risk zone: significant cancellation in mono is likely. Below 0.0 the channels are inverted and will cancel badly. A reading between +0.2 and +0.5 is a caution flag rather than a fault — it usually means the mix is wide and needs checking element by element rather than a global fix.

Does low stereo correlation always mean a phase problem?

No. Genuine width lowers correlation by design — a supersaw pad, a hard-panned double, or a wide reverb all read low while being perfectly correct. What matters is whether specific elements vanish in mono. Sum the mix to mono and listen: if the bass and lead vocal hold up, the low reading is intentional width, not cancellation.

Why does my mix sound fine in stereo but thin in mono?

Because mono sums the left and right channels, and anything partially out of phase cancels on the way. The usual causes are stereo wideners and the Haas effect, polarity-inverted stereo microphone pairs, layered duplicates that are not sample-aligned, and mid-side processing that pushes too much energy into the side channel.

How do I check mono compatibility?

Sum the mix to mono and listen on the actual system the mix will be heard on, then check the low end first — if the kick and bass lose weight in mono, that is your priority. Read the correlation meter while soloing elements so you can attribute a low reading to a specific source instead of the whole mix.

How do I fix phase cancellation?

Solo tracks while watching the correlation meter to find the offender. Flip polarity on one channel of a stereo pair, reduce the depth of a stereo widener or Haas delay, replace a phase-shift widener with a short 5 to 15 ms delay on one side, align drum overheads and room mics to the close mics, and keep the low end mostly centred. Then re-check the correlation in mono.

What does a phase alignment checker measure?

It measures the average stereo correlation between your left and right channels, on a scale from -1 to +1. Values near +1 mean the channels are nearly identical and mono playback matches stereo, values near 0 mean they share little in common, and a negative value means they are inverted. MixDiagnose's free phase checker computes this from your uploaded file and warns about the cancellation it will cause on mono playback.