rekordbox Auto Gain: why it does not reach your CDJ
rekordbox Auto Gain is a setting inside rekordbox. It evens out the levels while rekordbox is the thing playing the music, on its own decks in PERFORMANCE mode and in the DUAL PLAYER layout of EXPORT mode, 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.
The other way to even out levels in the file is to match integrated loudness to a LUFS target. A LUFS target or a true peak ceiling? compares the two.
Frequently asked questions
Does rekordbox Auto Gain work on a CDJ?
No. Auto Gain is applied by rekordbox's own decks and mixer, and the number stays in rekordbox's library. Exporting to USB does not write it into the file, so a CDJ reading that USB stick never sees it.
Where is the Auto Gain setting in rekordbox?
Preferences > Controller > Mixer > Auto Gain. Set it to Enable and rekordbox adjusts the volume of the track loaded on a deck (rekordbox 7.2.18 Instruction Manual, p. 242). Each track's value is shown, and can be changed by hand, with the Auto Gain knob in the GRID EDIT panel (p. 140), and the DUAL PLAYER layout of EXPORT mode has an AUTO GAIN control too (p. 122). Turn it off to hear the level that is actually in the file, which is the level a CDJ plays.
What level does Auto Gain aim for?
rekordbox does not document it. Measured on six tracks on 2026-10-02, each Auto Gain value equals about -10 LUFS minus the track's integrated loudness, to within 0.1 dB. So it evens out loudness at playback, raising tracks as well as lowering them.
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.
I re-analysed in Traktor and the auto-gain is still different on every track. Why?
Because Headroom aligns true peak, not loudness. After a run every track sits at the same ceiling, but a compressed master is still perceptually louder than a dynamic one that only reaches that peak on transients, and Traktor's Autogain, set at analysis to give an even output level (Native Instruments does not say what it measures), keeps giving each track a different value. What is left is the difference in dynamic range between your masters. MP3 and AAC also move in fixed 1.5 dB steps, so they land within one step of the ceiling rather than exactly on it. Leave Autogain on if you want everything equally loud inside Traktor, or switch it off to hear what a CDJ will play.
Where does the Mac app put its backups?
Next to the music, never inside the app's own storage. Each run creates a backup folder in the common parent folder of the tracks you processed, and a yyyyMMdd-HHmmss folder inside it for that run. In playlist mode that parent is the deepest folder every track in the run shares, and a playlist spanning two drives gets one backup folder per drive. The originals keep their folder structure, so you can copy them back by hand, and after a relaunch Restore from Folder… in Headroom puts a run back once you pick its timestamped folder.
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.
