How to Do Parallel Compression

How to Do Parallel Compression

You may have heard of mixing engineers talk about using parallel processing, and for good reason…it rocks! So what is parallel compression? Simply the mixing of the dry (uncompressed) signal with the wet (compressed) sound. I’ll cover some of the methods we use when mixing music and why parallel compression is used over normal (serial) compression.

What is Compression?

To start, we must know that compression lowers the dynamic range of a signal by ‘turning down’ the sound by a given amount (ratio) once it exceeds a set level (threshold). In actual usage, compressors can even out the dynamics of a track in a smooth, or aggressive way, depending on the type and settings of the compressor. Tweaking attack and release times massively impact the attack and sustain of a signal and how the sound is perceived by the listener.

Parallel vs. Serial Compression

Normally, a compressor inserted into a processing chain acts on the signal, and the now compressed signal is now passed on to any processors further in down the chain (more compressors, EQs, de-essers etc…) I personally still use one or two compressors in serial when I want to even out the dynamics of track or control peaks. The downside of serial compression is that an over-compressed sound can quickly loose ‘feeling’ due to lack of dynamics, loss of transients and the color the compression adds may be overpowering, causing pumping and other artifacts that aren’t pleasing.

When to use Parallel Compression

The benefit of using compression in parallel is that you can easily achieve the vibe, color, and thickness the compressor adds, without any of the unwanted side-effects mentioned above. Since the original signal is still intact, the transients and natural dynamics remain while the compressed signal can bring out sustain, attitude, and details due its condensed dynamic range and the compressor’s harmonic content.

How to Set Up Parallel Compression

  • Choose a colorful compressor for the job, we’re not looking for transparentness here. Usually, compressors are known for their harmonic distortion, overdrive, and quicker attack/release settings work well. Think 1176 (all-buttons mode), Distressor, SSL, TG1, PYE etc…
  • Method 1: Set up an auxiliary send in your DAW as a separate bus and send varying amounts from different tracks to this bus to be compressed. For example, for the drums, you may want to send all kicks, snares, and toms to an aux track with a Distressor absolutely crushing the signal. This will add sustain, grit, snap, and power to the drums in a way that normal compression can’t. You now have a new fader which controls only the compressed signal and you can mix it in as you see fit.
  • Method 2: More and more plug-ins include a MIX knob, where you can control the wet/dry blend directly in the plug-in itself. While this is very convenient and can work well on some sources, I find using method 1 (New York Compression) works better for my needs when it comes time to automate.

That’s all there is to setting up NY Compression!

You may be wondering how to use parallel compression on vocals.  Using the same type of setup, you can hyper-compress a lead vocal, bringing out every breath and nuance in the voice along with some harmonic distortion for grit. Blending this signal with a leveled vocal track works wonders and avoids the pitfalls of overcompressing the vox. You may need to automate breaths and sibilance down on this track as the decreased dynamic range can over-accentuate these features.<?p>

Louder isn’t always better! Be careful when blending compressed signals with the dry signal. Things will naturally be louder and it can be easy to overdo. A little goes a long way so blend to taste and then pull it back slightly.

Get Creative

The options are limitless and provide a greater degree of flexibility when mixing.

  • Try placing an EQ before the compressor to crank the low-end for a fat sound.
  • Send nearly the entire mix to be compressed and blend this in ever so slightly to achieve a louder, more full master.
  • Stack some distortion plug-ins on top of your compressor to get an even more crunchy sound (Decapitator, Kaya, Saphira etc…)

AUTOMATION, AUTOMATION, AUTOMATION! The key to getting the most out of parallel compression lies in automating your compressed bus throughout the song to prevent the sound from getting static. It works great to have the crushed bus muted or very low during the verses, and bringing them in for extra power in the choruses.

To check out some other mix tips, view this 121 Mix Tips with contributions from yours truly and other mix engineers.

If you’re struggling with your mix, do get in touch and I’ll be happy to help.

Go have fun, experiment, and try new techniques and compressors out on different sources and you’ll quickly get a feel for how parallel compression works.

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Virtual Mix Engineer