INPUT........To set the level going in.
THRESHOLD........This sets how high the signal must go before the compressor kicks in.
RATIO.......This sets how much compression is applied in ratio to the Db rise in signal level above the Threshold.
ATTACK.......This sets how fast the compressor kicks in once the Threshold has been breached.
DECAY........This sets how fast the compressor lets go, once the input signal has dropped back below the threshold.
LINK ......Links the two sides for stereo operation.
OUTPUT......Sets the output signal level.
HARD KNEE/SOFT KNEE
HARD KNEE
This form of compression kicks in as soon as the threshold ceiling is reached.
Let's say you have set a RATIO of 4:1......Once the threshold is passed, the compressor allows only 1db of signal level increase at the output,
for every 4 db in input signal level rise above the threshold setting......
On a Hard Knee compressor, this full amount of compression (as set by the Ratio) is applied in full, as soon as the input level rises above
the threshold.....This is a standard type of compressor.
PEAK & RMS MODEs
Some compressors, such as the Alesis 3630, allow you to switch between PEAK...and RMS operation. Practically, a compressor listens to the input signal
through the "SIDE-CHAIN" circuit, and then tells the VCA (voltage control amplifier) to apply compression when needed according to the adjusted setting.
The compressor will respond differently depending on whether it is monitoring the input signal in either Peak mode or RMS mode...
PEAK
The PEAK setting makes the compressor crush any signal rising above the threshold, no matter how fast the transient.....This is an ideal mode to use
for something like digital recording, where you need to absolutely stop any signals from overloading the input, because digital cannot be "saturated"
in the way tape can, and you get terrible digital distortion......Peak compression however is not very smooth or natural sounding, & can produce very
un-natural noticeable results unless you use a low compression ratio .....However, it can work well on fast attacking sounds like drums, working fast
to maintain a more even level for each drum hit.
RMS
The RMS mode setting is a more natural sounding mode, and responds similarly to the human ear...(Oh yes...human ears do have compression !!).......
RMS mode doesn't bother too much about quick short peaks that might cut through above the average signal level....even if you set a fast attack time..
RMS mode works on a wider average than PEAK mode, thus allowing some fast transients through, but closing down more when continuous loud peaks start to appear.
