Archive of the former Yahoo!Groups mailing list: The Yamaha AN1x Synthesizer mailing list

Tom asks:
"...what exactly does the compressor do with my sound? What ratio, etc. do i choose for what result?"

Phil replies:
"Here's something I wrote up a while ago. It's not specifically in relation to your example, but it may be an interesting read if you've never used a compressor before. It will give you a bit of an idea on what the various contols do. Please post back if you have any further questions.

Cheers,

Phil."


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Firstly, a Compressor doesn't actually 'boost' a signal - quite the opposite.
Here's a summary of how it works:

The signal enters the Compressor and leaves the Compressor unchanged...

UNTIL

...the volume of the signal exceeds the level you have set as the THRESHOLD.
At this point, anything that exceeds the Threshold is restricted by a rate
that you have set as the RATIO.

For example:

If the Ratio is set at 1:1 it means that for one dB that enters the
Compressor, you have one dB leave. - Effectively there is still no
compression applied.

Now, as you start to raise the Ratio value, compression starts to take place
everytime the volume exceeds the Threshold. The way the ratio works is:

1:1 1dB In / 1dB Out

2:1 2dB In / 1db Out

3:1 3dB In / 1db Out etc.

This continues up to say 10:1 where you need to have an increase of 10dB at
the input just to have a 1dB increase at the output. This sort of
compression is called "Limiting". You would use it to protect PA speakers in
a Concert/Nightclub, or when recording to DAT and you can't afford it to
distort. In this case, you would set the threshold so that the compressor
ONLY starts to operate on the absolute peaks of your music, rather than
compressing all the time.

You asked:
 "...When compressing, is it possible to get decent results by compressing
the whole track or do you have to compress one component of the track at a
time?"

The answer a combination of the above. I personally have quite a lot of
compression (ratio around 4 or 5:1) on my virtual-analogue synth leads to
level out their volumes, especially when making plenty of changes to your
filter settings which in turn affect the dynamics greatly and the pattern
won't sit nicely in the mix. A compressor helps level out the volume so that
you're not continualy adjusting the mixer fader levels.

And I also use a seperate compressor peforming mild compression (around 2:1,
and no more than say 4 or 6 dB of gain reduction incurred by the threshold)
over the Main Mix. Although the compressor is reducing the level of the
dynamic peaks, this allows you to turn up the main level, which in turn
lifts the volume of the quieter sections without increasing the maximum
volume.

This give the impression of things sounding louder when in fact the
compressor is simply reducing the volume of the peaks allowing you to turn
up the volume again to bring the levels to the same position.

It's a strange concept that you reduce the volume to 'get things louder'!

Keep in mind, that standard Compressor doesn't descriminate different
frequencies or sounds. If you have a continuous string pad sounding (for
example), then add a kick drum, as the compressor starts reducing the volume
of the peaks of the kick, this in turn reduces the volume of the pad for the
duration of the kick. A higher Ratio will emphasise this and while sometimes
this can be a cool effect, it is known as 'pumping' and is generally
undesirable.

There are compressors that in fact break the frequency band down into say 5
seperate bands and process each one seperately. This way you won't have the
deep bass frequencies modulating (or interacting) the other sounds in the
mix.

Hope this helps shed some light on the magic and mystery of compressors. Let
us know how you get on.

If you have any further questions (or debates) about what I've said then
please don't hesitate to post back.

Phil :)