Limiter Or Compressor? Learn The Difference!

Limiter Or Compressor? Learn The Difference!

Limiters and compressors are both dynamic range processors used in audio, but they serve different purposes and operate in different ways. While both tools control the volume and dynamics of a sound, their functions, applications, and settings can vary significantly.

1. Purpose and Function

  • Compressor:
    A compressor reduces the dynamic range of an audio signal by making the loudest parts quieter. It works by lowering the volume of audio signals that exceed a certain threshold, which helps to balance the levels in a mix. Compressors are typically used for smoothing out the dynamic variations in a performance, making the quiet parts more audible and preventing the loud parts from being too overwhelming.

    • Main Purpose: To control dynamic fluctuations and maintain a consistent level.
    • Typical Use: On vocals, drums, guitars, and other instruments to ensure they sit well in the mix without fluctuating too wildly in volume.
  • Limiter:
    A limiter is a more extreme form of compression. It is designed to ensure that an audio signal does not exceed a specific maximum level, usually 0 dB. In other words, a limiter will "limit" the signal from going above a set threshold, effectively preventing clipping or distortion that occurs when levels exceed the maximum allowable value. Limiters are often used in mastering to ensure the final output does not peak too high, especially in digital audio, where exceeding 0 dB can cause distortion.

    • Main Purpose: To prevent clipping and ensure that the signal doesn't exceed a specific threshold.
    • Typical Use: In mastering, broadcasting, or any scenario where you need to ensure the audio doesn’t peak above a certain level.

2. Threshold, Ratio, and Attack/Release

Both compressors and limiters have similar parameters, but how they work with those parameters differs.

  • Threshold:
    The threshold is the level above which compression or limiting will occur.

    • Compressor: A compressor will start to apply gain reduction gradually when the signal exceeds the threshold.
    • Limiter: A limiter applies gain reduction more aggressively once the signal exceeds the threshold.
  • Ratio:
    The ratio determines how much compression or limiting occurs once the signal exceeds the threshold. A higher ratio means more compression.

    • Compressor: Common ratios are 2:1, 3:1, or 4:1, meaning for every 4 dB above the threshold, the compressor will reduce the signal by 1 dB.
    • Limiter: A limiter typically uses an extremely high ratio, often infinity:1, meaning any signal above the threshold is limited (clipped) to the threshold level.
  • Attack Time: The attack time controls how quickly the compressor or limiter responds once the signal exceeds the threshold.

    • Compressor: A compressor can have a slow or fast attack time depending on how you want to control transient sounds (like the attack of a snare drum).
    • Limiter: A limiter usually has a very fast attack time, because it needs to respond instantly to prevent peaks from going above the threshold.
  • Release Time: The release time controls how long it takes for the compressor or limiter to stop processing after the signal falls below the threshold.

    • Compressor: A compressor’s release time can be set to different values depending on the musical context to create a smooth, natural effect.
    • Limiter: A limiter’s release is often instant or very quick, since it's designed to cut off anything above the threshold immediately.

3. Amount of Gain Reduction

  • Compressor:
    In a compressor, the amount of gain reduction depends on how far the signal exceeds the threshold and the compression ratio. A 2:1 ratio means a signal 2 dB above the threshold will be compressed down to 1 dB above the threshold.

    • Compressors allow for more subtle and gradual dynamic control.
  • Limiter:
    In a limiter, gain reduction is much more aggressive. Once the signal exceeds the threshold, it will be limited, and the output will not go above the threshold (unless the limiter is set to allow a small amount of "overshoot," often referred to as "look-ahead").


4. Applications and Use Cases

  • Compressor Use Cases:

    • Vocals: To smooth out variations in volume and ensure the vocal stays present throughout the track.
    • Drums: To control the dynamic range of drum hits, particularly snare and kick drums.
    • Guitar/Bass: To ensure that the instrument doesn't get too loud or too soft throughout the track.
    • Mixing: To control the overall dynamics of a mix and ensure a cohesive sound.
  • Limiter Use Cases:

    • Mastering: To ensure that the final track does not exceed 0 dBFS and cause clipping during playback or streaming.
    • Broadcasting: To ensure audio levels are within a safe range for radio or television.
    • Live Sound: To prevent distortion when amplifying audio in venues, ensuring the output doesn't exceed the maximum system levels.

5. Key Differences in Summary

Feature Compressor Limiter
Purpose Controls dynamic range, smooths out volume fluctuations Prevents peaks from exceeding a set threshold, avoiding clipping
Threshold Applies gain reduction gradually above a set threshold Applies severe gain reduction above the threshold
Ratio Usually a moderate ratio (e.g., 2:1 to 4:1) Typically very high ratio (e.g., infinity:1)
Attack Time Can be slow or fast depending on the application Very fast to catch peaks instantly
Release Time Adjustable release time for smooth or fast recovery Very fast, almost immediate
Amount of Gain Reduction Varies based on ratio and threshold Severe and quick, clamping down on peaks
Typical Use Mixing (vocals, instruments) to control dynamics Mastering, broadcasting, preventing clipping

Conclusion

  • A compressor is used to reduce the dynamic range of an audio signal, making quiet sounds louder and loud sounds quieter in a controlled manner. It’s more flexible and subtle.
  • A limiter is essentially an extreme form of compression, designed to prevent any audio from exceeding a maximum level (usually 0 dB), making it useful for avoiding distortion or clipping in the final output.

While both tools are crucial in modern audio production, limiters tend to be used for more final-stage applications (e.g., in mastering), whereas compressors are more commonly used throughout the mixing process to shape the dynamics of individual tracks.

By the Stealify Team! 

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