In this post, I’ll explain how to set up parallel compression. The procedure will work in any DAW – the only things you need to know is how to duplicate tracks and insert plug-ins.
In order to hear the effect you want to have an audio file at hand in which some quiet parts (maybe an open hi hat or a brushed snare) are overlaid by fairly intense transients (like a kick drum). We will bring those quiet parts up, instead of squashing the transients down.
Parallel compression in 5 easy steps
- Import your audio material onto a track and duplicate it. You want to have two absolute identical versions of your material. Note: If you have plug-ins inserted on your track, you must duplicate them as well.
- Put a compressor on only one of the two tracks. In case you already have plug-ins on the source track, the compressor should be inserted as last plug-in in the chain. It needs to be a compressor that provides fast attack times and low thresholds. The Waves R-Compressor is one of my favourites, but I found that most stock plug-ins also do a decent job.
- Now configure the compressor with the following initial parameters:
- Threshold: really low (-50 dBFS or less).
- Ratio: 2.5:1.
- Attack: as fast as possible (microseconds, if your compressor does it).
- Release: 250 – 350 ms.
- Knee: Hard.
- Now adjust the gain of the compressed signal using the make-up gain of your compressor until you hear an increase in volume of the quiet passages of your material.
- Now tweak the compression parameters to taste. Threshold and attack time should stay more or less where they are (really low and really fast). Ratio and release time will affect the subtleness of the compression.
Let’s hear it in action?
Here’s a drum loop, alternating between the original and parallel compressed versions. If you want, grab it and use it to experiment yourself!
A note on delay compensation
If you are mixing within a DAW you will need to pay attention to delay compensation. In the digital world, every plug-in needs some time to process the audio signal. Depending on the time needed this may lead to a delay of the signal. Therefore, if you sum two tracks with different plug-in configurations (one with, one without a compressor) you may run into phase issues.
If you are hearing a phaser-like sound when inserting the compressor on your duplicate track, you have latency issues. In this case, look for a function called delay compensation (or similar) in your DAW and enable it.
Finishing up with a book recommendation
The compression parameters mentioned in this post were taken from Bob Katz’s book ‘Mastering Audio – The Art and the Science’ which I highly recommend reading.
Please don’t forget to make some noise!