6.3 Compression 101

Compression is another important tool we have at our disposal.
As this topic can get quite technical, we will stick to the simplest form of compression.

To truly understand what a compressor does, we first need to understand the source material.

Here we have a waveform of a lead vocal. You can see that it’s quite dynamic, which means that the waveform shows that the loudest parts of the waveform have big ‘peaks’ and the softer sections are quiet.

When a compressor is used on a source, its job is to bring those loud parts down. Why would we want to do that?
We want to make sure we can hear the lead vocal at all times throughout the track. If we don’t use a compressor, then the loud parts may be too loud and the quiet sections may be too quiet. Our ear will constantly be straining to understand what the vocal is saying.
By levelling out the vocal using a compressor, it will sit in the track much more effectively.
Compressors aren’t just used on vocals, they are used on other instruments to help ‘level’ them out. Guitars, bass and drums are another three elements where compression can work really well. Alongside the volume control that compression enables, it can also add a specifically desired tone to the source.

There are many different types of compression. Here we will touch on three.

1. TUBE: Tube compression uses a hardware tube. This tube adds a ‘sound’ to our source, often giving it a vintage sound because of the slower response. This works great on vocals, piano and strings.
2. FET: FET stands for ‘Field Effect Transistor’. This type of compression does not have a tube and therefore has a different tone. With its fast attack time (see diagram below) it’s perfect for drums, bass and to add excitement to room mics.
3. OPTICAL: This type of compression uses an ‘Optical Cell’ which works similarly to a light bulb. As a signal passes through the cell, it illuminates like a light bulb and affects the way the attack and release (see diagram below) types work. It has an extremely warm tone and is fantastic for acoustic guitar and vocals.

Here we have a breakdown of some of the parameters of a compressor. This covers the main five elements that we will cover in our “DAW” module.