SonodexLossy or lossless
MP3 and AAC discard information that is barely audible to save space. 256 to 320 kbit/s is common; 320 kbit/s counts as the maximum for MP3. WAV and AIFF store uncompressed (CD quality: 1,411 kbit/s). FLAC and ALAC compress losslessly: the sound is identical to the original, the file usually about half the size of WAV.
What makes sense for DJs?
For a club sound system, lossless is the safer choice, because large systems show compression artefacts more clearly. MP3 at 320 kbit/s is enough for most gigs; 128 kbit/s sounds audibly thin. If possible, buy in lossless quality (Beatport, Bandcamp, labels). Important: converting an MP3 to WAV does not make it better.
Constant and variable bitrate
CBR keeps the bitrate constant, VBR adapts it to the material. Some DJ hardware only copes cleanly with CBR, because otherwise the position in the track is calculated inaccurately. For files that go onto a USB stick, it is therefore better to choose constant. Check your devices’ manuals for which formats they read.
Space matters too: 1,000 tracks come to around 10 to 12 GB as MP3 320, usually 30 to 40 GB as FLAC, and 50 GB and more as WAV.
In practice: unifying formats in the library
A library of mixed formats is normal, but check the weakest ones: anything under 256 kbit/s goes into its own playlist and is replaced when you get the chance. You keep lossless originals, even if you use MP3 for the stick.
Mind storage space and backup: FLAC saves a lot of space compared with WAV at the same quality and can be played in most DJ programs. Whether your player reads FLAC is stated in its manual.
Related terms
Frequently asked questions
Is 320 kbit/s MP3 good enough?
For most gigs, yes. On very large systems with deep bass, FLAC or WAV is audibly cleaner.
Why is FLAC smaller than WAV?
FLAC compresses without losing information, like a ZIP file for audio.