Explainer
What Is a Limiter in Audio? How Limiters Work and How to Set One
Updated 4 min read
A limiter in audio is a processor that stops a signal from going above a set level, called the ceiling. It's essentially a compressor with an extremely high ratio and a very fast attack, used to catch peaks and to make a mix louder without clipping.
Limiters are usually the last plugin on a master. They're simple to operate, with only a few controls, but each control changes the sound in a way that's worth understanding. If you're mainly trying to decide between a compressor and a limiter, our compressor vs limiter guide compares them side by side. This article stays with the limiter itself.
How does a limiter work?
A limiter watches the level of the incoming audio. When a peak would exceed the ceiling, it reduces the gain just enough to keep that peak at or below it, then lets the gain recover. The ratio is fixed so high it's effectively infinite: no matter how much louder the input gets, the output doesn't cross the line.
The way a limiter makes things louder is a little counterintuitive. You raise the input (or lower the threshold, depending on the design). The peaks hit the ceiling and get held there, while everything below them comes up. The loudest moments stay where they were and the average level rises, which is what your ears hear as loudness.
Limiter controls explained
Input or threshold
- What it does
- How hard you push the signal into the limiter
- Typical setting
- Until you see 1 to 3 dB of gain reduction on peaks
Ceiling or output
- What it does
- The maximum level that comes out
- Typical setting
- Around -1 dBTP on a master for release
Release
- What it does
- How fast the gain returns after a peak
- Typical setting
- Auto, or 50 to 200 ms as a start
Lookahead
- What it does
- Lets the limiter see peaks coming
- Typical setting
- A few ms; more is smoother but adds latency
True peak
- What it does
- Detects peaks between samples, not only on them
- Typical setting
- On, for masters
Character or style
- What it does
- Changes how the gain reduction behaves
- Typical setting
- Try each by ear; differs by plugin
Release is the control that shapes the sound most. A fast release recovers quickly, which sounds louder but can cause distortion on bass, because the gain moves within a single low-frequency cycle. A slow release is cleaner but can make the whole track dip after every loud hit. Many limiters have an automatic release that adapts to the material.
True peak detection matters because digital audio is stored as samples, and the actual waveform between two samples can peak higher than either one. Once the file is converted to analog or encoded to a lossy format, those inter-sample peaks can clip. A true-peak limiter catches them.
Types of limiters
- Brickwall limiters guarantee nothing passes the ceiling. This is what you want last on a master.
- Mastering limiters are brickwall limiters with extras: several release styles, true-peak detection, loudness metering and dither.
- Multiband limiters split the audio into bands and limit each separately, so a loud kick doesn't pull down the vocal. They work like a multiband compressor with limiter settings.
- Hardware and classic-style limiters come from compressors that could be pushed into limiting. Several well-known studio compressors have a limit mode or a very high ratio setting.
Limiter vs clipper
A clipper also stops peaks, but in a different way. A limiter turns the gain down for a moment, so the shape of the waveform is preserved and only its level changes. A clipper simply cuts off the top of the waveform at the ceiling. Hard clipping is instant and can sound harsh; soft clipping rounds the corners and adds harmonics, a lot like saturation.
Clippers are popular on drums and 808s and before a limiter on a loud master, where they shave the sharpest transients so the limiter has less to do. Heat is a saturation plugin with a soft clipper, not a limiter. Its Master Clipper preset uses the Tape mode with just 8% drive, a -1 dB ceiling and 40% softness. Listen to how it holds peaks at the ceiling by reshaping them rather than by turning the whole signal down.
Heat
Character
Clip & output
The real plugin engine, running in your browser: same DSP code and presets as the VST3/AU/AAX.
A common master chain uses both: a gentle clipper to take the edge off the sharpest peaks, then a limiter to set the final ceiling. Each one does a little, which tends to sound cleaner than either doing a lot. Heat handles the clipping stage; you'd still put a true-peak limiter after it.
When to use a limiter
- Last on the master. To set the final peak level and raise loudness for release.
- On a track with occasional spikes. A limiter after the compressor catches the odd shout or hard hit without changing the tone the rest of the time.
- On live input and streams. A limiter on a microphone channel protects a broadcast or recording from sudden peaks.
- On a bus feeding something sensitive. For example, protecting monitors or headphones while you experiment with feedback and distortion.
How to set a limiter on a master
- Get the mix right first. A limiter can't fix a mix that's unbalanced. If it needs heavy limiting to sound loud, the problem is earlier in the chain.
- Set the ceiling. -1 dBTP with true-peak detection on is a sensible default for streaming releases.
- Raise the input slowly. Watch the gain-reduction meter and stop when the loudest peaks show a few dB of reduction.
- Adjust release by ear. Listen to the kick and bass. If they distort or the track pumps, try a slower or automatic release.
- Compare at matched loudness. Turn the output down so the limited version is as loud as the bypassed one, then compare. If the limited version sounds flatter, back off.
FAQ
What does a limiter do in audio?
A limiter keeps a signal from going above a level you set, called the ceiling. When a peak would cross it, the limiter turns the audio down just enough and just long enough to hold it back. Push more level into it and the quieter parts get louder while the peaks stay pinned below the ceiling.
What is a brickwall limiter?
A brickwall limiter is a limiter designed so that nothing gets through above the ceiling, not even a brief overshoot. It uses an effectively infinite ratio, an instant attack and usually lookahead. Brickwall limiters are the standard last plugin on a master, where any peak above the ceiling could clip.
What should I set my limiter ceiling to?
For a master you're releasing, around -1 dBTP (true peak) is a common choice, because lossy encoding to streaming formats can push peaks slightly higher. Some engineers go a little lower for very loud masters. On individual tracks the ceiling is simply whatever level you want the peaks held at.
What does lookahead do on a limiter?
Lookahead delays the audio by a few milliseconds while the limiter's detector reads the signal ahead of time. That lets the limiter start turning down before a peak arrives, so it can reduce gain smoothly instead of clamping down instantly. The cost is a small amount of added latency.
Does a limiter reduce sound quality?
A little limiting on peaks is usually inaudible. Heavy limiting flattens transients, so drums lose their punch, and pushed too far it adds distortion and pumping. The more gain reduction a limiter is doing all the time, the more you'll hear it. A few dB on the loudest peaks is a safe range.