Tape machines are responsible for that analog warmth we miss in today’s digital recordings, just hear your favorite oldies records and you will hear that magical warmth. You can emulate the same analog warmth with tape saturation plugins. But first, let us understand the working of a tape machine.
When a signal is being sent to a tape recorder to be recorded, now the plastic film that you know to be the tape has a surface which is made of iron oxide powder to record a signal onto the tape the recording head of the recorder magnetizes each of the iron oxide particles on the tape by varying amounts over time this becomes a linear representation of the original alternating current this is where saturation comes in a tape recorder.
Whenever an input voltage goes beyond the set limit or saturation threshold of the tape, the iron oxide molecules on the tape reaches on its maximum magnetic potential and cannot be polarized further and so, cannot hold any more amplitude the result is that the signal is compressed and distorted in a nonlinear way.
This means that when signal from an audio passes the saturation point that part of the signal no longer represents the frequencies or amplitudes at the original state that is the actual signal which was sent to the recorder instead is a distorted compressed version now it’s important to understand what exactly happens to the frequency of a signal and saturation occurs.
So now, consider a sine wave at static frequency in an analogue system if it passes the saturation point the sine wave will be compressed and distorted so to create another sound containing the original sine wave frequency and random harmonics remember this only rarely applies to the part of the signal that passes the threshold in the digital domain.
Clipping is the same principle, however, the clipping threshold is much more determined and the clipping process is linear that is to say the compression and distortion processing is determined by strict algorithm functions those are described by a converter so with all that in mind most of you are wondering what does the saturation control of my compressor actually do well it emulates the previously described tape saturation by applying it to a portion of your signal .
In many cases, saturation control will have threshold and ceiling parameters just as with any other processing threshold determines the level at which the saturation is introduced ceiling will generally determine the maximum saturation level and you would normally set this to the peak of your transients but you can lower it for harsher effects.