rekordbox Auto Gain: why it does not reach your CDJ
rekordbox Auto Gain is a performance-mode setting. It evens out the levels while rekordbox is the thing playing the music, but the number it works out is never written into the file. Export to USB and the number stays behind, so a CDJ reading that USB stick never sees it. What was even on the laptop is not even in the booth, and that is why one track in the same set needs the trim at three o'clock while the next sits at noon. Bake'n Deck's Headroom writes that gain into the file itself.
Where it stops
| Where it lives | Survives the USB export |
|---|---|
| The Auto Gain value, on the rekordbox side | ✗ no |
| Beatgrid and cues, in the file and the XML | ✓ yes |
| Gain written into the file | ✓ yes |
The shape of the problem is the same one playlist order has: anything rekordbox does in software stops at the laptop. Key and BPM sorting disappears for exactly the same reason.
What writing it into the file does
Headroom measures LUFS and true peak on every track and applies exactly one gain change per track. Quiet tracks come up, loud ones come down, and every track lands under the same true peak ceiling, -0.5 dBTP, which is the AES TD1008 §7B figure.
- No limiter. The shape of the waveform does not change and the dynamics stay as the master left them
- Not loudness matching. What gets aligned is the true peak ceiling. The differences between tracks survive, and the rest is still your ears
- MP3 and AAC are rewritten without re-encoding. For MP3 it is a rewrite of the global_gain field, so the decoded audio is bit-identical apart from the gain
- Files are rewritten in place, so cues and beatgrids stay linked. Every run is backed up first and restore is one click
The trim knob is on the mixer, and it is the old, quiet file that gets cranked. That is the part that goes away.
Frequently asked questions
Does rekordbox Auto Gain work on a CDJ?
No. Auto Gain is a performance-mode setting and the number stays on the rekordbox side. Exporting to USB does not write it into the file, so a CDJ reading that USB stick never sees it.
Why are my tracks different volumes on a USB stick?
Because the tracks themselves differ in loudness. Inside rekordbox, Auto Gain is absorbing that difference; the correction does not travel past the export, so the trim knob on the mixer ends up doing the work.
Does writing gain into the file hurt quality?
MP3 and AAC are rewritten without re-encoding. For MP3 it is a rewrite of the global_gain field, so the decoded result is identical.
Is a limiter or compressor applied?
No. Exactly one gain change per track, and the shape of the waveform does not change. Dynamics stay as the master left them.
Will every track end up at the same volume?
No. What gets aligned is the true peak ceiling, not loudness. The differences in dynamics between tracks survive, and the rest is still your ears.
Do cues and beatgrids survive?
Yes. Files are rewritten in place, so nothing on the rekordbox side comes unlinked, and every run is backed up first.
Can I use Bake'n Deck with Traktor, Serato or Engine DJ?
Yes. Headroom rewrites the audio file in place: same path, same duration, same number of samples. MP3 and AAC are not re-encoded at all, and the binary marker frames DJ software writes into a file are carried back over byte for byte. Nothing a cue point or a beatgrid is anchored to moves, so every app keeps its analysis.
My DJ app has its own auto-gain. Does that conflict?
It needs one step. Traktor, Serato and rekordbox each store a gain value from their own analysis, and once the level in the file changes that stored value still describes the old one. Either re-analyse the tracks, or switch the app's auto-gain off so you hear the ceiling baked into the files. That second option is also what a CDJ does with a USB stick, which is the case Headroom is built for.
I prep in rekordbox and play in Traktor. Which one should I run this from?
Either. Headroom works on the files, not on a database, so both libraries see the result and both keep their cues. Sync tools like Lexicon match on file paths, which do not change. Run it on one playlist first and check a couple of cue points; every run is backed up first.
Get Headroom
Bake'n Deck for Mac is on the Mac App Store: pick a playlist, analyze, check every row, then apply. The baken command line is free and MIT licensed.
