Limiters

Limiters are devices, algorithms, or systems that constrain an input signal or quantity to predefined bounds, preventing damage, reducing distortion, and enforcing safety across various fields.

Audio limiters monitor signal amplitude and reduce gain whenever the input exceeds a preset threshold, preventing clipping while preserving loudness. Unlike traditional compressors, limiters apply a high ratio and fixed thresholds, often with fast attack and configurable release times. In mastering and live sound, they help maintain consistent levels and protect speakers.

Electrical and electronic limiters protect hardware by capping current or voltage. Current-limiting devices, regulators, and fuses act as limiters to prevent overheating or damage. Mechanical limiters restrict motion, such as travel limits on actuators or safety stops. Speed limiters in automotive and industrial settings cap maximum velocity or torque for safe operation.

Software and control systems use limiters to regulate event rates and state evolution. Rate limiters constrain the number of requests or data packets over time to prevent overload, while control-system limiters prevent actuator saturation by bounding state variables or control signals. In mathematics and signal processing, a limiter can refer to a nonlinearity that saturates an input to a specified range.

Design considerations include choosing bounds and response characteristics such as attack and release times, soft versus hard limiting, and potential artifacts like distortion or clipped signals. Proper limiting balances protection with preserving signal integrity and performance; safety standards may apply.

Applications span audio engineering, power electronics, robotics, industrial automation, and network services. Common variants include peak limiters in audio, peak-current limiters in power supplies, and rate limiters in software services.