Crest Factor — The One Number That Tells You If Your AI Mix Is Alive or Crushed
When mastering a track from Suno or Udio, a lot of people focus only on whether it's "loud enough." But the real reason a song feels dull and fatigues your ears fast is often dynamics, not loudness. The number that shows the health of those dynamics is the crest factor.
What crest factor is
It's simple: peak (the loudest instant) minus RMS (the average level), measured in dB.
- A wide gap → the punchy transients are alive.
- A narrow gap → loud and quiet parts barely differ, so the whole track is one squashed block.
In other words, crest factor tells you whether a track is breathing or being crushed.
What's a healthy range
There's no single right answer across genres, but the rough working ranges are:
- Below 6 dB — over-limited. Punch is gone, and fatigue sets in fast.
- 6–12 dB — the healthy modern zone. Loud, but still breathing.
- Above 12 dB — under-mastered. It'll sound small and flat next to commercial releases.
The point isn't to hit a target number — it's to use where you land to judge whether you've crushed the track or haven't finished mastering it.
Why it collapses on AI music
AI-generated tracks often come out already heavily compressed. Rather than each instrument having distinct dynamics like a human recording, the whole thing arrives somewhat flattened.
Push a hard limiter on top of that — thinking "louder is better" — and the already-narrow crest factor collapses further. The result is a paradox: the volume goes up, but the song feels smaller. Loud and full are not the same thing.
The most common misconception: "louder is better"
Loud doesn't mean alive.
A crushed 3 dB master actually sounds smaller and duller than a healthy 9 dB one at the same LUFS. And streaming services normalize loudness on playback — so the volume you forced gets turned back down anyway, while the dynamics you crushed don't come back.
That's why "as loud as possible" is an especially losing strategy for AI music.
How to check and restore it
- Measure first. Most DAW meters or free loudness meters show peak and RMS (or short-term LUFS) together. The gap between them is your crest factor.
- Suspect the limiter. If your master-bus limiter's gain reduction is excessive, dynamics die there first. Backing it off slightly often lets the track breathe again.
- Keep glue compression light. Bus compression that holds the track together needs only 1–2 dB of gain reduction. More than that is crushing, not gluing.
- A/B at matched volume. When comparing to bypass, always match levels — it avoids the "louder just sounds better" illusion.
The takeaway
If you only watch "how loud," you'll miss the song's life. Check the crest factor once and you'll see at a glance whether your track is crushed or simply not finished. Streaming handles loudness for you — but dynamics, once lost, don't come back.
To master an AI track with the right crest factor for streaming, you can preview it free (no account) at antiaimaster.com.