One knob compressors are increasingly common on small analog audio mixing consoles. We’ve put this guide together to help you learn what that single knob is doing when you turn it up and down.

How Does A Compressor Work?

The goal of using a compressor is to reduce the dynamic range of an an audio input. An audio compressor will generally do two things:

  1. Reduce the output of a signal that is above a certain threshold
  2. Increase the output of a signal that is low

In order to do this, audio compressors typically have five different variables:

  1. Threshold – This is the point at which the compressor will kick in. The higher the number, the “louder” the signal will be before it is compressed.
  2. Ratio – Once the audio signal exceeds the threshold, this is the ratio at which the audio will be compressed. Common settings are 1:2, 1:3, 1:4
  3. Gain – This is how much you want to raise the gain on the entire channel. This is how you increase the volume of things that are perceived as being quiet. 
  4. Attack – How fast the compressor kicks in.
  5. Release – How fast the compressor releases.

How Does A One Knob Compressor Work

A one knob compressor obviously needs to combine a bunch of the variables involved in order to simplify the process for the audio engineer who is using it. 

If we use the Yamaha one knob compressor as an example, the chart below demonstrates the Threshold, Ratio, Gain, Attack, and Release of the compressor when it is off compared to when it is at full. If the compressor is at half, you can estimate the values for each variable.

Compressor OffCompressor Full
Threshold18 DB-7DB
Gain0 DB7DB
Attack25 ms25 ms
Release300 ms300 ms

Looking at the chart above we can see how the first three variables (Threshold, Ratio, & Gain) change while the attack and the release of the compressor remains the same. 

One Knob Compression Chapters

  • 0:00 – Introduction
  • 0:40 – What Does An Audio Compressor Do?
  • 2:13 – How A Typical Compressor Works
  • 5:50 – How A One Knob Compressor Works
  • 7:41 – What Setting Do I Use?
  • 7:53 – Final Thoughts

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