In The Studio: Clarifying The “Mystery” Of Compression

ProSoundWeb

Compression can be used to control the transients of a sound. A transient is a very sudden and short loud part of a sound. Percussion instruments have loud transients that can sometimes overload.

If they are reduced in volume so that the transients are well within safe limits then everything other than the transient may be so low that noise is heard.

A good solution is to set the threshold of a compressor so that only the transient triggers the process, and set the ratio so that the transient is under control but still effective.

Analog tape compresses naturally as it hits tape saturation levels. Since analog tape works by magnetizing the oxide particles on the tape and there is only so many particles, eventually every single particle will be magnetized.

That is the saturation level of magnetic tape. If you try to load more gain on the tape beyond that level, then the sound will be squished together in a process called tape saturation or tape compression. This compression is particularly warm and is sometimes relied on for end of mix compression.

Compression occurs at various places, and the sum of all compression on each individual instrument is important to consider. What kind of compression you utilize at which stage of the mix chain is important.

If you have a level controlling compressor on a vocal, and then an overall compressor on your mix output you are actually compressing the vocal with two compressors.

Many people do not realize how changing mix compression will affect how individual instruments are themselves compressed.

Some people used to count on the compression from tape saturation as part of their sound. They simply were not finished until they had slammed their mix to a piece of half-inch. Me, I used a tape and an alignment that was slightly more conservative but accurate for most of my work but used tape that had a nice compression for multitrack or mix-down recording when the music called for that particular sound.

I’m often asked, as a matter of signal flow, should compression be placed before or after EQ. If compression comes first, then it is to either control level or to thicken the sound itself and then add an EQ contour.

However, if compression comes second, then you change an overall sound that you then thicken or control.