What are the differences between peak and RMS limiting in a mix?

1 Peak Limiting

Peak limiting is a type of compression that reduces the level of the loudest peaks in your signal, preventing them from clipping or exceeding the maximum headroom of your system. Peak limiting is useful for protecting your speakers and your ears from sudden bursts of noise, such as drums, snares, or vocals. However, peak limiting does not affect the average level or perceived loudness of your signal, which depends on the RMS (root mean square) value. Therefore, peak limiting alone may not make your mix sound loud enough or balanced enough.

2 RMS Limiting

RMS limiting is a type of compression that reduces the level of your signal based on its average or RMS value, rather than its peaks. RMS limiting is useful for increasing the perceived loudness of your mix, by making the quieter parts louder and the louder parts quieter. RMS limiting can also help you achieve a more consistent and even sound across different tracks and sections. However, RMS limiting can also introduce more distortion and artifacts, especially if you apply too much gain reduction or use a fast attack and release time.

3 How to Use Them Together

The best way to use peak and RMS limiting in your mix is to combine them in a serial or parallel configuration, depending on your goals and preferences. Serial limiting means applying peak limiting first, followed by RMS limiting. This can help you tame the peaks and then boost the loudness, while preserving some of the dynamics and transients of your signal. Parallel limiting means applying peak and RMS limiting separately, and then blending them together with a mix knob or a bus. This can help you retain more of the original signal and avoid over-compression, while still adding some loudness and punch.

5 How to Choose the Attack and Release Time

The attack and release time are two other important parameters that affect how fast or slow the compression or limiting reacts to changes in the input signal. The attack time is the time it takes for the compression or limiting to reach its full amount, and the release time is the time it takes for the compression or limiting to return to its original amount. To choose the attack and release time for peak limiting, you need to consider the type and speed of the peaks you want to control. A common practice is to use a fast attack and release time for transient peaks, such as drums or percussion, and a slower attack and release time for sustained peaks, such as vocals or synths. To choose the attack and release time for RMS limiting, you need to consider the overall groove and feel of your mix. A common practice is to use a medium attack and release time for most genres, and a faster or slower attack and release time for more aggressive or smooth genres.

6 How to Avoid Common Pitfalls

Compression and limiting can enhance your mix, but they can also ruin it if used incorrectly or excessively. To prevent this, you must use your ears and meters to apply compression and limiting with care and purpose. Additionally, it is important to compare your mix with reference tracks and check it on different speakers and devices. Over-compressing or over-limiting your signal can make it sound flat, lifeless, or distorted. Under-compressing or under-limiting your signal can make it sound weak, thin, or inconsistent. Compressing or limiting too many tracks or buses can create a muddy, cluttered, or noisy mix. Compressing or limiting without listening can lead to poor decisions and unwanted results.