Welcome to the Classic Optical Compressor: a 100% analog old-school compressor from the days where colouring was an important factor to the sound. The four controls (from left to right) are the Gain, which controls the ‘pre-glow’ of the optical circuit (the more you turn this up, the fatter the sound); Level, which controls the overall volume of the compressor; Compression, which controls how hard or soft the compression is, and the Attack control which takes the signal from transparent to outright total squeeze. A short time with this compressor will allow you to find some of those classic guitar sounds which may somehow have escaped you before. Again, like all the Vintage pedals, the Classic Optical Compressor comes in a solid diecast housing with cool chicken-head knobs, CM colour and graphics and a 9V battery compartment. Due to the nature of compressors, we highly recommend a regulated power supply (like the CM ProPower) or a large stock of batteries.