Let’s start with the basics. A compressor is an audio device which condenses the dynamic range of a signal. Using a compressor, loud sounds get reduced in volume while softer sounds get raised. Most music heard today contains compression, particularly on vocals. Learn how to use compression and take your DJ career to the next level.
How does a compressor work?
We use compressors to make changes to the sound’s amplitude (volume). Usually to make it more punchy and louder in the mix. Compressors allow you to fine tune a few key settings in order to control changes to both the amplitude and time of the signal as it passes through. All of those knobs on a compressor have different duties. Let’s look at what some of these knobs do.
Threshold
The threshold knob is a gatekeeper. When it’s set to 0dB, the full signal is allowed through unchanged. But as you turn it down (towards negative infinity), more of the audio gets processed. So the threshold is just a way of determining the volume level at which the audio begins to be processed. The lower the threshold, the more of the audio will be compressed.
Ratio
So, let’s say our threshold ‘gatekeeper’ allows everything under -12dB through to the next stage. What happens next? Well, any audio above -12dB is then due to be compressed. How compressed? That depends on the ratio. Ratio is the strength of the compression. A gentle ratio might be 2:1. This means that for every 2dB of audio above our -12dB threshold, only 1dB will make it through. The rest gets squashed! So if we the ratio is 2:1, 2db of signal louder than the threshold is only ‘worth’ 1dB. What’s the point of this function? Remember, a compressor is great at making loud peaks and spikes softer and more pleasing to the ear.
Make-Up Gain
Like most audio devices in a chain, compressors have an option to raise and lower the gain once its job has been done. Gain is the most simple and common parameter in audio processing. Remember, a compressor typically makes loud sounds quieter and more consistent. It reduces spikes in the mix. As a result, the overall sound is usually quieter after passing through a compressor. Make-up gain simply allows you to turn it back up to match the levels in the mix.
Most DJ software includes the ability to add compression to a mix. It’s tempting to crank it all the way up, but do be aware that too much compression makes a mix sound lifeless and flat. Find the balance by learning how to DJ with care and confidence that your mix is sounding good. Sign up for a DJ course online today and kickstart your DJ career!
John Bartmann is a music producer and DJ.