Limiter

Simple Explanation

A limiter is like a "hard ceiling" for sound. No matter how loud the input signal gets, the limiter stops it from crossing a specific point. it is used to make sure the audio doesn't distort or "clip," and to protect speakers from being damaged by sudden loud noises.

Concise Technical Definition

A dynamic range processor with a high compression ratio (typically 10:1 or higher, often infinity:1). It enforces a strict maximum output level, known as the ceiling, by reducing the gain of any signal that attempts to cross the threshold.

Layman-Friendly Analogy

Think of it like a speed limiter in a car. You can push the gas pedal as hard as you want, but the car’s computer will not let you go faster than 100 mph. The "gas" is your volume, and the "limit" is your safety barrier.

Industry Usage Summary

Essential in live sound, broadcasting, and mastering. In live sound, it acts as a safety net to prevent equipment failure. In mastering, "Brickwall Limiters" are used to maximize overall loudness without allowing the digital signal to exceed 0 dBFS (clipping). It is also used in "Multi-band" applications to control specific frequency ranges, such as harsh sibilance or boomy bass, without affecting the rest of the sound.

Engineering Shortcut

A "Brickwall" compressor. If the ratio is 10:1 or higher, you are limiting. Use a Look-ahead feature to catch fast peaks before they happen.

Full Technical Explanation

A limiter is functionally a compressor with an extremely high ratio and a very fast attack time. While a standard compressor "squeezes" a signal, a limiter "clamps" it. There are three primary types:

1. Peak Limiters: These react to the instantaneous highest points of a waveform. They are used primarily to prevent digital clipping and protect hardware.

    

2. RMS Limiters: These respond to the average power of the signal over time (Root Mean Square). They are used to prevent thermal damage to speaker voice coils by ensuring the sustained energy doesn't exceed safe limits.
    

3. Band-Limited (or Multi-band) Limiters: These apply limiting only to specific frequency clusters. This allows an engineer to "tame" a specific problem area (like a piercing 3 kHz frequency) without reducing the volume of the entire track. Modern digital limiters often feature Look-ahead technology, which delays the signal by a few milliseconds to analyze the incoming peak and apply gain reduction exactly when the peak hits, ensuring a perfect "brickwall" response.