Making compression work.

farss wrote on 11/10/2005, 4:34 AM
I should have posted this ages ago but you know how it is. Sorry if this is general knowledge but I suspect not, sure had me fooled for a while and the now departed Red confirmed that it certainly was considered a source of confusion by the audio guys, well unless you took the time to study the manual very carefully.

This doesn't just apply to compression but as it's one of the few FXs affected by the level of the audio it's the one where it matters most.

Put simply the track FXs are pre the track volume envelopes, not post as one would quite likely think looking at the visual layout of the tracks and the headers. So if I apply compression in the track header with a knee at say -10dB but my audio is peaking to -16dB then the compressor isn't going to be doing much at all! So one would logically add a volume envelope and dial in say 12dB of gain. Except that still does nothing, that's only adding gain after the compressor so it (the compressor) is having no effect at all.

To make the compressor and the volume envelope do what you'd think it should do here's what you need to do.
Either add the Compressor FX to the master bus or if you only want to apply compression to one track, add another bus to the mixer, assign the track to that bus and apply the compressor to that bus master.
Why it's this way made no sense at all to me until I got my brain around how a real audio desk works, the track FXs are the equivalent of the insert FXs, which are pre the faders, duh.
Bob.

Comments

Chienworks wrote on 11/10/2005, 5:08 AM
Now there's a good wish-list item for Vegas 7: a pre-post switch for track FXs. That too is something that most mixers have.
MarkWWWW wrote on 11/10/2005, 6:04 AM
Alternatively you can add the effect to an Assignable FX chain - these (like the busses) can be selected to be either pre- or post- fader.

The output of the Assignable FX chain can be routed to the master or to any of the busses you may have set up.

By default Busses are set up to be pre-fader and Assignable FX chains are set up to be post-fader, but both the busses and the Assignable FX chains can be configured to be either pre- or post-fader.

Mark
douglas_clark wrote on 11/10/2005, 7:24 AM
Another approach if you use the Sony Track Compressor is to add an FX Automation envelope for the compressor Input Gain, so you can "ride" the volume going into the compressor. Right-click on track header > Insert/Remove Envelope > FX Automation > click on Track Compressor in the plug-in chain > check Input Gain parameter. This gives you a pre-compressor gain envelope on the track, which you can tweak. An additional advantage of this approach, if you have a quiet track, is that the compressor input gain parameter goes all the way up to +25dB, compared to only +6dB for the Volume plug-in.

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Erk wrote on 11/10/2005, 8:04 PM
farrs, many thanks for your post! I didn't realize this was how things were setup, but it now clarifies some behaviour I couldn't understand before.

Greg
ibliss wrote on 11/11/2005, 11:07 AM
you guys seem to be making this over complicated.

USE THE THRESHOLD CONTROL

- if you're audio is peaking at -16, then lower the threshold below -16.