FastBikerBoy
I see no reason why the vocal track can't be used into the sidechain of a gate/compressor on the delay buss.
You can insert as many buss sends as you want on a track/buss. I still don't think that's the best way to do what the OP is trying to achieve though. Envelope on the delay buss send level is the way I'd go.
Because if you use a plugin that does not allow 100% wet (like my case), then the delay buss does not play just the delay signal. It plays the dry signal as well--and you do not want to compress the dry signal, only the delay.
This is the reason I would not use envelopes: I am trying to achieve this sidechain effect in order to prevent the wet signal from drowning out the main vocal signal while still maintaining loud delay effect tails. So basically, every time the singer sings in the song, the wet delay is lowered a little bit so that it does not overpower the main vocals. Does this make sense?
FastBikerBoy
At 100% wet it should be delay only. If it isn't then the answer to your question is you can't. Either use a different delay (the sonitus for example) or a send envelope on the delay.
But the thing is, I can't set it to 100% wet. The dry signal is fixed, and I can only raise/lower the delay volume. I can't change the dry volume.