Aux tracks: what's the difference between routing to an aux and sending to an aux?
I’ve been helping a mentee get her head around some basic routing concepts, and I thought they might help someone else!
For context: this person wanted to add a little compression to her master bus. She had been reading about using aux tracks, and she uses Cakewalk, which allows you to do sends from the master bus, so she did a send from the master bus to an aux and put compression on the aux.
Logical! Also, totally not the right way to do it for a master bus. This is where our conversation picked up; here’s her question, followed by my response:
Are you saying that if I direct a track to a send then the track and the send both go to the main? Or does the track go through the send to the main?
It depends how you direct it. There are two ways to direct a track to an auxiliary bus:
You can route the track to the auxiliary bus. This removes the track from being sent directly to the master bus, and replaces that routing with a routing to the aux.
This is how you do, for example, a drum bus, or a backing vocals subgroup. You route all the tracks in question to that aux, so that you can treat them in a single place — for example, putting compression on your whole drum kit at once, or eqing your backing vocals as a group.
You can send the track to the auxiliary bus. This is what you did. This keeps the track routed directly to the master bus, and also supplements that routing with a parallel routing to the aux.
This is how you do, for example, an fx send, like reverb or delay or whatever. you send all the tracks that you want the effect on to that aux, in whatever amount you want them to receive that effect that you have put on that aux.
When I direct the main to a send, is the end result main plus send or main through send?
When you send a signal to an aux send — option 2, above — that send goes in parallel with the direct output routing. Main plus send.
Directing the main to a send in this way is a weird circular routing, and frankly I’m surprised Cakewalk lets you do it.
This is because everything eventually goes through the main out, including the aux return that you’re sending to — the main out is comprised of everything that you hear, i.e., the sum of everything that is making sound.
So when you send the main to an aux, the return for that aux then goes back into the main ... which gets sent to the aux ... which goes back into the main ... to infinity.
This is what's known as a feedback loop! If you turned the send or the aux return up loud enough, it would literally create feedback (unless Cakewalk has anti-feedback technology under the hood to prevent this sort of thing from happening).
If you want compression on your main out, just simply put a compressor plugin there (before the limiter). If you want parallel compression — i.e., a little bit of the compressed signal mixed in with the uncompressed signal — which is what it seems like you were maybe going for by doing an aux send from the mains and putting a compressor on the aux — then use a compressor with a Mix knob and set the Mix knob to mostly dry.
If anyone reading this has follow-up questions, hit reply, and I’ll address them in a subsequent post if it feels like that might be illuminating!
Hope this helps — jamie