It’s a vital instrument in studio recording, music mastering, and mixing to prevent peaking and clipping. Let’s define these concepts. A limiter is a device that prevents all audio (digital or electrical) from reaching a particular loudness. However, it’s generally utilized at the maximum amplitude to minimize peaking.
Let me spell out the strategy before we go any further. We’ll define an audio limiter, discuss its sibling, the compressor, and explain when and how to use the limiter. With no technical jargon, you’ll know what you need to know. Let’s start.
What is a Limiter?
A limiter is a signal processing tool (like mixing music) that compresses the dynamic range. It can take an input signal, assess its amplitude (volume), and reduce the waveform’s peaks if they exceed a threshold. For example, if we set the limiter’s threshold at -5 dB, no audio will be louder than that. The music becomes louder as it approaches the point, but the maximum loudness is capped.
When mixing in the box, we usually set the threshold to 0 dBFS (decibels Full Scale). We use +24 dBu for analog measurements (decibels unloaded). Anything over these points is termed ‘peaking.’ Unintentional peaking causes distortion, ruined recordings or broadcasts, and even heat damage and blown speakers. This is because a limiter uses clipping purposely yet tastefully.
The Limiter vs. Compressor Difference
Compressors are used to compress the dynamic range. A threshold is set at a decibel level, and any audio over that level is decreased in loudness by a ratio you may select.
The ratio is adjusted at 3:1 (three-to-one). Thus, only one decibel emerges from the opposite side for every three decibels beyond the threshold. The compressor would lower -1 dB to -7 dB.
That’s tricky. If you’re curious, you may read our article What is a Compressor? It allows some audio loudness above the threshold while decreasing it. It stops.
When to Use a Limiter
This section may have been named “Why do we employ a limiter?” There are three primary causes:
- First, to safeguard our live equipment.
- To prevent inadvertent peaking in live recordings.
- Boosting audio loudness while mastering
The last thing you want is a severe electrical surge zapping your expensive power amplifiers and mixing boards. Worse, some musicians abuse their guitars to the point of damaging speakers (and hearing damage for the listeners).
You may have the ideal take in a music studio, but certain portions are distorted. You may have to erase the interpretation and retake it, but you will never obtain a flawless performance from your singer or musician. A limiter would have prevented that peaking.
Mastering professionals utilize limiters to boost an audio track’s loudness (like a song). For example, if you can get loud portions like snare drums close to a limiter’s threshold without distortion, you can boost the song by 5 dB using make-up gain.
Because stupid big label execs and TV ad writers believed shattering your eardrums would favorably attract your attention, everyone now strives to be as loud as possible.