Dynamics Processor (Compressor)

Compressor

Analog Compressor

Dynamic Range Compression: or simply compression is a process that adjusts the level of a signal generated by a sound source. Compression can be used on a recording, live in a sound, or broadcasting to control the audio volume. The device used to apply this effect is called compressor and can be analog or digital.


The maintenance of the signal level within limits causes a decrease in varição between the peaks and valleys of the waveform, thus reducing the intensity of dynamic changes. The use of this effect may prevent high levels of unwanted signal or noise at low levels of signal, providing a greater amplitude control.


Its use can also be done in order to deliberately distorting the original sound, from the maintenance of high levels of signal.


The compressor is nothing more than a button for "volume", whose main parameters are:

Threshold: Point of reference signal amplitude, from which the compressor should act.


Ratio: correspond to the compression ratio. Indicates an attenuation of the signal amplitude. Any sign that exceeds the threshold point, it should be mitigated as the rate chosen. Ex: (2:1 / 3:1 / 4:1 / ∞: 1)

Rate ∞: a compressor becomes a limiter.


Attack: Time it takes for the compressor to lower the amplitude established.


Release: Time to return the compressor to the amplitude to the original level (without attenuation)


Compression Modes (Hard Knee, Soft Knee)


The Knee control the curve of the response curve, which is an acute angle and has a rounded edge. Soft Knee mode slowly increases the compression ratio increases as the level and eventualment


Soft Knee: a simple solution to the problem caused by a sudden change in gain when the signal crosses the threshold. Since the problem is caused by the fact that the sudden change of gain is because the "knee" in the response curve is a closed curve, the solution is to soften the sharp bend in a gradual curve. This response is called a soft knee for obvious reasons, as can be seen in the figures below.

Soft Knee

Soft and Hard Knee

Types of Compression Peak or RMS


PEAK mode the attack and release controls are available to the user. In the RMS mode, the compressor operates with the times "average"usually defined by the circuit set by the manufacturer. It is extremely important that a good learning experience for you always work PEAK mode, so you can understand the results of compression each time you change any of the parameters.


G. R. Meter

Gain Reduction Meter. Indicates the amount of signal attenuation in dB.


Sidechain

It is an alternate entrance that some compressors can have. Enables control of compression from an external signal. The signal coming through only to shoot serce sidechain compression that is connected to the input device.