you've grouped your tracks together and like a good citizen you're compressing the bus to keep the dynamics under control. but then for one reason or another you need to ungroup the tracks; maybe you want to group your group with other groups, maybe you want to split the grouping. but as soon as you degroup this group, however, you'll lose the bus compression! the whole point of compressing a group of signals is to have the sum total influence the dynamics of each other so you can't simply place a the same compressor on every track. and printing the sub-mix isn't always an option when you plan to change things later. it's usually at this point you get all in a fuss. well, no longer:
here's where we're at: we've got a group of tracks and we like the way they sound with the compressor. we'd like to keep the sound the same but you also want to ungroup.
- duplicate your group and ungroup the new copy
- mute the original and rename it something like 'sidechain'
- grab the compressor from the original group
- turn on the sidechain option and select the muted group ("sidechain") as the input
- now copy this to each of the now-ungrouped tracks
- one easy way to do this quickly is to hold 'option' as you drag it onto the next track. this duplicates the device and you can just drag it to every track you want it on
with the sidechain on your track will be compressed in the exact same way it was as part of the group. the sum of the signals will still influence the signal but you have the flexibility of degrouped tracks.
one of the more practical applications for this technique is in bouncing stems. you can sidechain your master bus onto copies of your master limiter on each of your tracks so that they sound the same when they are re-summed in a new project.