Hi.
I will try to explain (with my bad english
) some of the basics.
Let's say you've got a signal from a VCA (Voltage Controlled Amplifier). This could be from a syntheshizer.
This signal has it's charcter, bass, middle, high tones, volume ...
You can change the volume of the signal ... but it's just the maximum / minimum volume of the whole signal.
This can you do with an amplifier.
When you've got more than one 'hard' signal, maybe a bassdrum an a bassline it could happend, that both peaks of the sounds are 'too much'. So it's too loud, you can't clearly listen to other sounds, sounds distorted, crushed ....
To fight against this you're able to use a limiter, compressor, peak controller .. maybe in a kind of side chaining.
Limiter:
A limiter is a circuit that allows signals below a specified input power to pass unaffected while attenuating the peaks of stronger signals that exceed this input power.
Features of a limiter could be:
Ratio, Attack and release, input / output-volume
Compressor:
Dynamic range compression, also called DRC (often seen in DVD and car CD player settings) or simply compression, is a process that reduces the dynamic range of an audio signal, that is, narrows the difference between high and low audio levels or volumes.
Features of an compressor could be:
Threshold, Ratio, Attack and release, Soft and hard knees, Peak vs RMS sensing, Stereo Linking, Makeup gain, Look-ahead
Peak Controller:
'Grabs' the peak of a signal for using on other VCA. For Example you can use the peak of a bassdrum for changing the volume of the bassynth. You can use this trick for 'ducking' or 'pumping' the sound.
Useful links in Wikipedia (some stuff i've copied into this tread)
Compressor:
http://en.wikipedia.org/wiki/Dynamic_range_compression
Limiter:
http://en.wikipedia.org/wiki/Limiter
VCA:
http://en.wikipedia.org/wiki/Variable-gain_amplifier
hth
E.SoX