Discover Powerful Parallel Processing

As you may already know, audio signals can be processed using many tools called effect units. Producers and engineers often insert them directly into the signal chain so that the unit captures and affects 100% of the sound. They often combine the unaffected signal (dry) and the affected signal (wet). This technique is called parallel processing. It preserves the source's presence, character, and location while still coloring it and allowing you to control the balance.  

Parallel Compression

You've probably heard of parallel compression if you're familiar with audio compression. In that case, you know that compressors bring loud levels down and low levels up - thus reducing the dynamic range. However, since our ears are way more sensitive to the high levels being limited than the low levels being boosted, a new technique was born to highlight upward compression. Therefore, it is perhaps the most utilized implementation of parallel processing. In addition, it lets you make sounds bigger while retaining their dynamics and makes the compression artifacts less evident (since the compression is being done on low levels). This means you can drive the compressor harder than in serial without damaging the sound. It also allows you to adjust the amount of compression in the mix with faders instead of parameters.

Moreover, there are several ways to achieve parallel compression in analog and digital setups. An analog design requires some re-routing of signal and, of course, auxiliary tracks (since you can't simply duplicate/create tracks like in a DAW). In this blog section, I will demonstrate a quick way to set this up digitally in Lumit.

First, drag an instance of Lumit's Compressor/Expander onto the track you wish to process. This unit will address the downward compression aspect by gently reducing peaks above the threshold. Set its parameters to something like this.

Create a return track and call it something like comp. Insert another instance of Lumit's Compressor/Expander onto it. This will address upward compression.

Set its parameters to something like this...

Bring up the send fader for the comp on the instrument track.

Experiment with the balance between the track's output, send output, and the return track's output until you hear something you like. Listen to the drastic difference between serial compression and parallel compression. Notice how parallel compression preserves the details and presence of the kick drum better than serial.

Serial Compression

Parallel Compression

Parallel Distortion

Like in parallel compression, parallel distortion gives you control over the amount of distortion in the ultimate output of a source. Since you can distort at low levels in this configuration, it allows you to drive the effect a bit harder than you could in serial distortion without it doesn't sound good. That is why the source comes through clean but not TOO clean. This is how you set up parallel distortion in Lumit using a bit crusher. Create a return track and drop an instance of Lumit's bit crusher onto it. To make it something like a crush.

Set its parameters to something like this...

Remember, don't be afraid to drive parallel effect units. A unit this damaging may destroy an excellent recording in serial but can be balanced when used in parallel. Bring up the send fader for the track you wish to parallel distort.

Listen to the drastic difference between serial and parallel distortion on this synth sound.

Serial Distortion

Parallel Distortion

Parallel Reverb

I would argue that parallel reverb is critical to a professional-sounding mix. That is why almost every software reverb (and some hardware units) features a dry/wet parameter. I expedite the process by performing the duplication and merging for you. The drawback of dry/wet knobs is that you can't further process the wet signal independently like you can using return tracks. P parallel reverb simulates standing in front of a performance in a room because you get both the direct and reflected signals. Furthermore, serial reverb (100% wet) can sometimes make the source sound far away in space, with an ambiguous location.

Check out this processing method in Lumit that involves serial and parallel reverb. I used the technique to separate early and late reflections such that the early reviews are serial and the late considerations are parallel. This provides a realistic sense of space.   Additionally, drag an instance of Lumit's reverb unit onto the instrument you wish to affect (in serial) and set its parameters below. Ensure the wet balance is 100% and the ER/LR balance is set entirely to ER.

Furthermore, create a return track like the previous examples and drag another instance of Lumit's reverb unit onto it.

Set this unit's parameters to something like below. Set the dry/wet parameter to fully wet and the ER/LR parameter to fully LR.

Then, bring up the send fader on the instrument you're affecting.

I would advise you to experiment with the balance between the instrument's level, send level, and the return track's level until you're happy with it. In the end, listen to the drastic difference in spatial orientation between the serially processed sample and the sample processed using this technique. Moreover, the second example shows that the reverb tail and sense of space are more realistic.

Serial Reverb

Parallel Reverb