Sound & signal
Peak and VU meters
A peak meter shows the highest instantaneous level, catching transients a fraction of a millisecond long. A VU meter averages over roughly 300 milliseconds, so it shows something much closer to perceived loudness.
In practice
Peak catches transients, VU shows loudness. Match records on the averaging meter, never on the peaks.
On club mixers the channel meters are usually peak-reading, which means gain-matching by eye is approximate at best. Use them to stay out of the red and use your ears for the match, or use a meter that averages if the mixer offers one. The rule that survives either way is that a dynamic record and a limited record showing the same peak are not the same loudness, and the difference will be obvious to the floor and invisible to you.
Instant
What peak reads
~300 ms
What VU averages over
Your ears
What actually matches them
Where these come from: Standard meter ballistics — published specifications, not catalog figures. The measured spread of mastering levels across the catalog is on the gain page. For what we can measure, see the modern loudness measure.
Why it matters
They disagree constantly and both are right, which is why a mixer with only one of them misleads you in a predictable direction. A punchy record with big transients reads high on peak and moderate on VU; a squashed, heavily limited one reads the same on both — and it is the second that is actually louder in the room.
That is the whole reason gain-matching by eye goes wrong. Matching two records so their peak meters agree matches their transients rather than their loudness, and if one is dynamic and the other is not, the quiet-looking one will be the one that hits.
Frequently asked
Why do two tracks at the same meter level sound different?+
Because a peak meter is showing transients rather than loudness. A dynamic record and a squashed one can peak identically while the squashed one is clearly louder in the room.
Which meter is on my mixer?+
Almost certainly peak-reading. That makes it good for staying out of the red and unreliable for matching two records by eye.
Is LUFS better than either?+
For loudness, yes — it averages over a long window and weights by how the ear responds. Peak still matters for knowing whether you are about to clip.
Related terms
LUFS
LUFS means loudness units relative to full scale — a loudness measurement weighted to match how ears hear rather than what a peak meter reads. Streaming platforms and DJ software both normalise to a LUFS target.
RMS
RMS is an average of level over a short window rather than an instant reading. It tracks how loud something actually sounds far better than a peak meter does, which is why VU-style metering is built on it.
True peak
True peak is the highest level a waveform actually reaches between the samples that describe it. A file whose every sample sits below the ceiling can still overshoot it once a player reconstructs the sound.
Gain
Gain sets how hot a track arrives at the channel before anything else touches it. Most club mixers label the same control trim. It is a correction for how a record was mastered, not a volume control for the room.
Explore: LUFS meter · LUFS · True peak · All DJ terms