Compression: A compressor effect pedal creates sustain without adding distortion or clipping the signal. The compressor controls the volume. If the signal starts to fade, the compressor increases the volume. The compressor will also reduce or limit the signal if it gets to loud.
Simpler Description: Compressors find that happy middle ground, and can make notes last longer.
Types of Compression:
Optical Compression: This type of compression uses a light source and light-sensitive resistor to adjust the volume of the signal. This is an especially smooth compression that is easy to get a good sound out of, and is very natural sounding.
FET Compression: A classic form of compression borrowed from a studio favorite. The gain is controlled here by a FET (Field Effect Transistor), which is a type of transistor favored for its ability to emulate vacuum tubes among its many other benefits. This type of compression is known for adding a certain “smack” or “snap” to the sound. This is great for all types of playing with the right settings, but especially handy for funk, reggae, ska and other genres where that signature snap can be useful.
VCA Compression: This is by far the most common type of compression found in guitar pedals. VCA stands for Voltage Controlled Amplifier. This is a method of gain control in which the AC guitar signal is converted to a DC voltage. That voltage tells the VCA when to turn up or down. VCA compressors are exceptionally useful due to a wide range of attack/release times and great controllability which allows them to simulate the sounds of a slow, smooth optical compressor and a super fast, snappy FET compressor. It’s an all-around great style of compression for when the need to handle a wide variety of material arises.
Effect Pedal Examples:
Common Internal Components:
Fifty Favorite Effect Pedals for Sale: