Greg Wurth explains that a compressor is a device designed to reduce the dynamic range of an audio signal. He goes over the typical ways that they are used: to effectively level a signal, and as an effect to add a desired coloration to a signal. He describes four main types, which are optical, FET (field effect transistor), VCA (voltage-controlled amplifier), and tube (variable mu).
- In this chapter, I'll explain what a compressor is, as well as its basic operation. I'll go over four types that are used in professional recording studios and explain their differences. These types are optical, FET, VCA, and tube, or variable mu. Optical designs usually have simple control, such as gain reduction and gain makeup. FET designs are much more versatile as they offer control over input, output, ratio, attack and release.
VCA designs are also versatile, offering similar controls. Variable mu designs also have similar controls but having much slower attack and release time. A compressor is a device designed to reduce or control the dynamic range of an audio signal. Compression is typically used in two ways. To level a signal and as an effect to add a desired coloration. It should be noted that sometimes limiters are referred to as compressors and vice versa.
The difference is that a limiter is designed to specifically prevent peaks from going above a specified point and is set to a very high ratio of 20 to one or higher. A compressor has an adjustable ratio that typically ranges from two to one to 20 to one allowing it to control much more than just peaks. For all intents and purposes, I'll refer to everything in this chapter as a compressor but keep these differences in mind. Throughout this chapter, I'll share audio examples of each type of compressor.
I want you to listen closely to recognize the different tonal characteristics and effect of the different controls on the various sound sources. The idea is to help you retain this information so that you can make informed compressor choices the next time you record or mix.
Throughout the course, Greg shares images, diagrams, and audio examples that can help you grasp how this equipment functions, and why you might want to opt for one piece over another. Greg dives into working with different kinds of microphones and preamps, describes the main types of compressors and equalizers, and shows how an analog-to-digital and digital-to-analog converter works. Plus, he covers analog summing—the process of combining multiple audio channels down to a stereo signal—and analog emulation.
- Dynamic, condenser, and ribbon mics
- Tube mic preamps and solid state mic preamps
- Different types of compressors and equalizers
- Analog-to-digital and digital-to-analog conversion
- Analog summing
- Analog emulation