Some might get confused sometimes when compressor, expander and gate are discussed and especially when concepts like “upward”, “downward”, “parallel” or such-like are thrown in. Fortunately, things can easily be explained just by looking at the according transfer curves and as an added sugar some more sophisticated insights can be obtained es well.
Opposed to VCA, Variable-Mu or FET based approaches, opto-electrical compression takes advantage of using a light-sensitive resistor and a small light emitter (a LED or electroluminescent panel) to obtain a gain reduction voltage in the sidechain path. This technique is well-known to add some smoother gain riding characteristics to the signal because of the specific attack and release response which comes from the inertia and inherent memory effect of the photoresistor element. [Read more…]
Beside the envelope design for the control signal the compressors transfer curve is the most influencing part speaking in terms of the resulting sound impression. If we ignore any time dependend behaviour of the compressor for the moment then it basically works like this: Signals at a level below a certain threshold are passing through the device unaltered. Reaching the threshold level the input signal gets lowered by a certain ratio. The result is a so called “hard-knee” transfer curve. [Read more…]