[fruityloops] Re: A compression tutorial, of sorts - CORRECTION

  • From: "Gwydion Elderwyn" <Gwydion@xxxxxxxxxxxx>
  • To: <fruityloops@xxxxxxxxxxxxx>
  • Date: Thu, 22 Aug 2002 13:30:43 +1000

> Compression of 2:1 would make the signal half as loud.

Ack, did I say that?  Oops.  That's not right!  What I meant to say was,
compression of 2:1 would make the signal *over the threshold* half as loud.

Hmmm.  It might be easier to show you a few examples.

Say my threshold is -10db.  A signal comes in at -8db, ie, 2db over my
threshold.  2:1 compression would reduce this difference by two - so the
outgoing signal would be -9db.

If I was applying 4:1 compression, then only one quarter of the difference
would remain - so instead of being 2db over it would leave being just 0.5db
over - ie, a level of -9.5db.

Pop quiz:  My compressor is set to 6:1 compression with a threshold
of -15db, and it just received an incoming signal at 6db.  What level will
the compressor output?

Finally, this should now show you why a compressor with "infinite"
compression is the same as a limiter.  If you reduce the overflow to
(1/infinity) of the value it was before, you've basically taken the
difference away completely, so the outgoing signal will be at the threshold

Hopefully that's the only mistake I made ;)

Take care,

PS: The pop quiz answer is as follows.
The difference between the threshold and the signal is 9db.  9db divided by
the ratio (6) is 1.5db, so the outgoing signal would be (threshold + 1.5db),
which is -13.5db.  How did you do?

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