Parallel processing is a technique that is used in most mixes, whether for compression, EQ, saturation or other effects, even sometimes just the idea of duplicating a track without putting anything on it works well in music processing.
For those who do not know the principle, parallel processing consists in “copying” a track or a slice, and applying any processing on this track, and then mixing it with the first.
There are several popular ways to process music in parallel.
Parallel compression and EQ
Parallel compression is a fairly simple but very effective technique, applicable to many situations – both in the context of mixing and mastering.
It consists of taking a track (or a buss) and duplicating the signal to obtain two identical tracks. And also used especially for drum sounds, but nothing prevents you from using it on other sources.
With parallel compression, the original track remains intact. It does not touch the transients.
On the second, we apply compression affecting the entire signal, not just the peaks. This second track is then more or less subtly mixed with the first
In practice, parallel compression becomes interesting when you push compression to the extreme, but it can happen in some cases where you lose certain information in terms of frequencies, which you can catch up with by applying an EQ before or after compression depending on the desired effect. If you want to keep some transparency with your EQ, you can try a linear phase EQ.
Distortion and EQ
As with parallel compression, you can apply distortion to your signal. Saturation is also interesting because you will reduce the dynamics of your signal in addition to saturating it. Which can give a very nice energy and textures.
The parallel distortion is used on the drums or bass, and sometimes to get a very saturated sound, which can also give a feeling of frequency loss that can be filled with an EQ. Just like parallel compression or any other “extreme” treatment that you can provide.
Chorus and compression
When it is necessary to give width to a sound, and that the latter is of mono and central tendency, applying a compressor to this sound, can accentuate the effect of presence and width in the stereo.