Parallel compression is a technique dynamic range used in sound recording and mixing, a combination of dry signal mixed with a compressed version. It uses a send and return setup similar to sending signal to an effects processor. Also known as Upward compression or New York compression.
The benefits of using parallel compression is you get to keep your dynamics in the signal whilst adding some oomph that the compressor gives you giving that extra body in vocal. Typically when using a compressor you use it to reduce the dynamics clamping down on the peaks making even overall signal. But with parallel compression you get to keep the dynamics whilst still getting that lush richness that the compressor would provide. Depending on the settings used, compressors can give very different results. It is generally accepted that compressors can work on micro- dynamics (altering the inner dynamics or peaks of individual instruments) and macro- dynamics (altering the overall loudness of longer passages) (Elmosnino, S 2018)
To do that its best to duplicate the signal either have it lightly compressed or not compressed at all whilst the other copy is squashed to the extreme. Then set the compressor to a send select and choose the route out to new track. If the source track is in mono its then keep the parallel compressed track mono and that way you do not run into phasing issues and so on. Keep it on aux input and then rename it to something like P comp then press ok and it will give parallel compressor track. There are a couple of things that need to be done and the first thing with the send level that is being sent needs to be set to unit gain right away and this can be set by pressing the option key and click on the send level fader to set it to unit gain. You would also want to make sure the send is a pre fader send so that once you have the squashed copy of the signal you would use the tracks faders to balance the levels between the compressed and the uncompressed signals. If you do not set the track they send to a pre fader send and anytime you would want to change the original track fader it will change the level going to the compressor which will ultimately change the amount of compression you are getting, which you I advise no to do.
Once done you can add in the insert window any of your favorite compressors or use the limiter plugin as the whole point is to squash the signal by any means necessary. Turn the ration all the way to squash or smack or high ratio 7-1 then turn up the input a little bit then jump to the mix window then unmute the lead vocal then reduce the level of the parallel compression all the way down. As you are mixing slowly the add the compressed track into the mix and when you find the sweet spot just leave it. Take time to listen to before and after so you can hear the difference. After that you can play around with a 7 band EQ and use a high shelf to boost the high frequencies and the do the low end to give a nice boost it which also helps on the drums to give a boost. Use the bypass just to hear the difference and continue tweeking it to your taste buds. I am looking forward to this process when I start to mix my songs.
Elmosnino, Stephane. Audio Production Principles : Practical Studio Applications. Oxford University Press, 2018.
(2019). Izotope.com. Retrieved 4 November 2019 from https://www.izotope.com/en/learn/5-ways-to-use-parallel-processing-in-music-production.html
(2019). Izotope.com. Retrieved 4 November 2019 from https://www.izotope.com/en/learn/expanding-on-compression-3-overlooked-techniques-for-improving-dynamic-range.html