9. Parallel Processing
Parallel processing comes in many forms, but the most popular (and sometimes misunderstood) is parallel compression. Unlike regular compression, parallel compression is best thought of as a technique for ‘filling in the gaps’ between the higher peaks of a signal.
In effect this means that this type of compression is less prone to heavy squashing and allows the processed material to maintain its punch, transients and definition, while also appearing bigger and more full.
We’ll start with a single uncompressed bass track:
Then we’ll duplicate it (we could also route it to an aux channel):
Now we’ll apply heavy compression to the second version only. Use a fast attack, medium release and very low threshold to ensure we dial in a lot of gain reduction. You may have to apply quite a bit of make-up gain here to compensate for the gain reduction.
Here’s how the heavily compressed duplicate sounds on its own:
Here’s how it sounds as we slowly bring up the level of the compressed version until we reach the point where it sounds just right, making the bassline thicker and heavier:
Some compressor plugins even have a mix control built in. The Output Mix control in Logic’s compressor allows parallel compression to be set up without the need to copy the track or route to an aux bus.
Compression isn’t the only effect which lends itself to parallel processing. You can try something similar with parallel distortion, for example, which allows the distorted part to be processed separately – EQd, filtered and tweaked until the overall sound is just right. The distorted parallel channel can even be automated, introducing a more distorted version of the sound during certain parts of the song or emphasising certain sections.
It’s important to remember that distortion also adds harmonics higher up the frequency range, which may help to thicken out the sound further and make it more prominent in the mix but can also potentially clash with other instruments. There’s little point adding a load of high frequency harmonics with distortion only to cut them back out with EQ when you mix the track.