Contrary to popular belief compressing audio does not make the sound source louder, but in fact it does the opposite. Compressing audio makes things less loud. Simply put, compressors take loud passages and automatically pull the volume down at a designated threshold. It’s like a automatic fader.
Now let’s go through why we use compressors. Compressors can do many functions in a recording studio. They can be used as a tone box – like using the 1176 with the compressor chain turned off for the transformer color. They can be used to distort – think how a Distressor or LA2A works. I was once told by a mentor that: “Compression Equals Distortion. And Distortion Equals Distortion.” And it’s stuck with me ever since. A simple truth that I come back to on a daily basis. That said, we use compressors to even out elements of a source that we want to smooth out, dynamically. Theoretically we should be working with musicians and singers who are well trained and rehearsed, but that isn’t always the case and putting a compressor in the signal chain can help a musician sit better in the mix, not to mention simply sound better and more refined.
There are a few universal knobs on compressors that are a good thing to learn inside and out:
- Threshold – How loud the signal must be before the compressor itself turns on.
- Ratio – How much compression is applied. A ratio of 4:1 will output 1 dB for every 4 dB of input signal that exceeds your targeted threshold.
- Attack – How quickly the compressor will engage. You can get pretty creative with this knob.
- Release – How soon after the signal dips below the threshold the compressor stops compressing.
- Output – This is overall output level and one uses this to match up the gain lost in compression. This is often called “Makeup Gain”.
One of the best ways to learn how compressors work is to simply run a loop in to the compressor and play with the knobs while keeping note of what you are modifying and how it’s manipulating the sound. Go crazy. Learn a little. You can’t break it. Even when breaking it can be the goal.