# Compression – Jargon Busting

Threshold -o->

Level at which the compressor starts to work.

Example -16db is peak level = <= set level at -18db => everything above -18db will be compressed

Ratio -o->

Amount of gain reduction to be applied to signal that exceeds threshold level – see above…

Attack -o->

Measured usually in milliseconds or ms => time taken for the compressor to start working.

Release -o->

As with attack but this time = time taken for compression to stop working – tail off as level drops below threshold.

Make-up -o-> the amount of gain applied to ‘make up’ gain reduced by compressor.

Knee -o-> soft or hard – decides wether the response curve has a sharp or rounded edge.

–o–>Example of use

Let’s say we have a vocal track that has an average level of -16db

(note the use of minus, this is because we are -16db below 0db)

So again a vocal track at -16db

We set our threshold at -18db(minus 18db)

Which is ‘2‘ below our tracks peak volume of -16db

Everything above -18db will now be worked on by the compressor.

So now we set out compressors ratio to 2:1

This means a 2 to 1 reduction.

–~o-> Oh no maths time…

our peak is -16db

our threshold is -18db

we have 2db exceeding our threshold

ration 2:1 means that every db above threshold will be reduced/divided by 2

therefore that 2db will become 1db and our level will now show at –17db

Make sense?

Now if we wanted to get our volume back up to -16db we can do this by adjusting our make up gain.

Also by using the attack and release settings we can decide how quickly we want the the comprssor to start and finish working.

It’s a lot to take in really – and it’s best actually experimenting with a compressor to see what is what.

It took me quite a while to get my head around it but eventually it started to sing in.

Have Fun…

Updated: June 3, 2009 — 5:56 am

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