Stereo to mono downmixer
Mix a stereo recording down to mono with a documented formula, and see how likely the left and right channels are to cancel each other first.
Accepted files: .wav,.mp3,.m4a,.aac,.flac,.ogg,.oga,.opus,.webm,audio/*. Choose one file. Up to 256 MiB in total.
One stereo recording up to 256 MiB and 10 minutes; custom coefficients from -2 to 2. WAV is read with every sample intact; other formats are decoded by your browser at 48 kHz. Everything is processed on your device and nothing is uploaded. Download: mono WAV in the source format or the format you choose, and a JSON report. Left and right are mixed into one mono channel. Up to 1,000,000 characters. Review the settings before running.
Your result
How to use Stereo to mono downmixer
- Choose a stereo recording.
- Pick a mix formula, or enter your own left and right coefficients.
- Mix down and read the correlation and cancellation risk.
- Download the mono WAV and the JSON report.
Useful next steps
Formulas
Average is 0.5 times left plus 0.5 times right, which never clips. Minus 3 dB uses 0.7071 for each side, which keeps the loudness of uncorrelated material but can clip on loud centred sound. Left or right keeps one side only. Custom uses your own coefficients from -2 to 2.
Cancellation risk
The report gives the correlation of the two channels over the whole file. Below 0 the channels are often out of phase and parts of the sound will cancel in mono, so the risk is high. From 0 to 0.3 it is moderate, above 0.3 low. The mono fold-down change compares the mid level with the average channel level.
Before you export
If the risk is high, check the source for a channel with inverted polarity, or use the left or right formula instead of a sum.