Check your mix before mastering
The mix check reads a finished mix and shows what is worth looking at before you master it: clipping, phase problems in mono, the low end, DC offset and silence at the ends. It is free, it runs in your browser, and it never stops you mastering.
What you need
A finished mix as a WAV, FLAC, AIFF or MP3 file. WAV or FLAC is best, because the check flags an MP3 as a lossy source. Chrome can’t read AIFF, so export a WAV to check it there.
A browser. You do not need an account. A long or high-resolution file can be too large to check in any browser, on a computer as well as a phone. See If the file can’t be checked.
Jump to a step
1. Open the mix check
Go to the mix check. It is also listed under Tools at the top of the website, beside the LUFS meter.
Drag a mix onto the page, or press Choose an audio file. The file is measured on the page: your audio and its file name are not uploaded or saved. Our analytics can count that a check ran, with rounded results such as a loudness band and how many fixes it found.
2. Read what it found
Findings come in three groups:
- Fix before mastering: something mastering cannot put back, such as clipping, an MP3 source or real phase trouble in mono. Each one says what to do next.
- Worth knowing: something to look at, which may be fine on purpose, such as a mix that is already loud, silence at the start or end, or a 16-bit file.
- Checks with no flagged issue: everything that came back clean. The app calls this group Fine.
A finding that happens at a certain moment is marked on the waveform. A finding tells you where to look; your ears decide whether the mix needs a change.
Press Copy findings to send them to whoever mixed the track, or to keep them for the next bounce.
3. Fix it and check again
Make the change in your session, export the mix again, and choose the new file. If everything reads as you want it, the mix is ready to master.
4. Check it on the upload page
You can skip the separate page. When you choose one mix on the upload page, a Mix check card appears under the file and reads the mix in your browser while you choose a loudness. Your audio is not uploaded until you start mastering.
The card only advises. You can master straight away whatever it says, or press Choose a different file to swap the mix first.
The card does not appear when you upload several songs at once, or in the upload box on the homepage. Use the mix check page for those. It takes several files at a time.
5. See the check on your master
Every master repeats the check on the file you actually uploaded. On the job page, Your mix, checked shows the engine’s reading, taken before mastering, and Every reading opens the full list of numbers.
The numbers can differ slightly from the ones your browser showed. Use the job page’s numbers when you need a record: they are the ones that go on your delivery report.
6. If the file can’t be checked
The mix check page and the upload card can both refuse a file. Neither stops you mastering it.
- This file can’t be read in your browser: your browser could not open the file. Chrome can’t open AIFF, for example. Export a WAV and choose it instead. The upload card shows this same line when a file is too large to check.
- This decoded file exceeds the local memory limit: the mix check page can’t hold the file. Its limit depends on length and quality, so a long or high-resolution file can reach it on a computer as well as a phone, and a phone can run out of memory sooner. Export a shorter section to check, or a lower sample rate if you want the whole length.
Or skip the browser check and master the file. The engine reads the whole mix itself, and the result appears under Your mix, checked on the job page. The upload page tells you if a file is over your length limit.
Next: Master a track. To see what was delivered afterwards, see Read and share your delivery report.