The art of compression is yet another paramount technique for mixing engineers. A compressor is delicate tool with a diverse range of applications throughout sound design, mixing and mastering.
Compression can create punch, power and consistency as well as extract tone, improve clarity and increase loudness. When used in a different application, compression can glue sounds together, create better mixes between sounds alike or even punch holes into audio allow tight drum mixes.
Typically, punchy drums are desirable yet drums that have too much punch, or too much dynamic range. When a drum has too much dynamic range, the transient can sound piercing and body can sound flat, and weak overall.
A compressor can be used to create dynamic range for a brief moment after the transient of a drum to create more punch but also restoring the body of the drum relatively quickly as to not over-compress, squeezing the life out of the drum.
Do not overload one compressor with too much information to deal with or else the device may begin to fail and introduce distortion as a by-product. Using a sequence of two or more compressors is not an unusual technique. The first compressor can deal with the transient of the drum while the second can operate on the body or tail of the drum.
The threshold will determine how loud compression will begin to engage. This value depends entirely on the source material and may vary drastically from sample to sample. Focus on how much compression the loud parts of your signal should receive when setting the threshold.
The ratio will determine how strong the threshold can maintain compression. The higher the ratio, the more resistant the threshold meaning the greater the effects of compression per decibel. Once the ideal attack and release times have been set along with the optimal threshold, the ratio can be set last to determine overall effects of the compressor.
The attack time will determine how fast the compressor engages once the threshold has been exceeded.
The release time will determine how fast the compressor will disengage once the signal falls below the threshold.
The attack and release times should mimic the source material. For instance, for drums and fast information, use quick times. For vocals and bass, slower times sound more natural.
A soft knee will cause the compressor to begin engaging as the signal approaches the threshold before crossing it, while a hard knee will cause the compressor to engage only when the signal has been reached or exceeded. Soft knee is ideal for low frequencies and bass sounds while a hard knee is ideal for transient information and higher frequencies.