Welcome to the next in our series of tutorials which give you an exclusive look at our brand new online Audio Mastering course featuring Waves plug-ins.
What is parallel compression?
Parallel compression is a technique which consists of splitting into two the signal to be processed. One path is the original signal (unprocessed), the other path is a compressed version of the signal, both signals are then mixed together. This technique is usually more common in mixing than mastering, where typically a ‘heavily’ compressed signal is mixed to the uncompressed version. This method has been used by quite a few mix engineers in New York City and became known as New York Compression.
It is vital that both signals are completely locked in to avoid any phase and comb-filtering effects. This should not be an issue when using only analogue equipment, however digital processors such as compressors will introduce a small delay and therefore your compressed signal will be slightly late compared to the original. If using parallel compression with digital hardware you will need to adjust the time of the original signal to match exactly the compressed version. Most DAWs such as Logic have a feature called automatic delay compensation, which means that the delay will be calculated by the software.
Some compressors have a balance control allowing to blend the uncompressed and the compressed signal within the compressor device (sometimes labelled dry/wet), although most engineers prefer to have the two separate signals for more control.
The sound of parallel compression
Parallel compression is considered by some engineers to be able to offer a more transparent type of compression. Although we use downward compression, the compressed signal doesn’t contribute as much to the overall signal. Because the compressed signal is mixed with the uncompressed version, we are able to retain more of the ‘quality’ of the peaks while raising the gain of the low levels.
Parallel compression can be used to bring up the low or mid levels of the music and is often used for upward compression. It can also be used to ‘beef up’ and add punch to a mix without the side effects that we can get when we push a downward compressor.
Adding some attitude!
In this tutorial Doug Shearer demonstrates how to use parallel compression to bring attitude, punch, warmth or bring out the mid levels of a piece of music. This technique can work well with more modern popular tracks (rock, hip-hop or dance for instance). The settings for the parallel compressor will be quite different from the previous example. You should aim to achieve a gain reduction of about 3-5 dB, up to 8 maximum. The threshold can be set right in the middle of the music, ratio will be determined by how aggressive you want the compressor to be. You will need to use a fairly long attack time (from 120 ms), release time should be set according to the music.
The Audio Mastering course has been developed by JC Concato (Mix engineer: The Cure, Erasure, US3) and Doug Shearer, with contribution from top industry professionals, Jim Lowe (Producer, engineer: Stereophonics, The Charlatans) & Bunt Stafford Clark (Mastering engineer: Thom Yorke, Manic Street Preachers, Aloe Blacc). The aim of the course is to help you understand the role of the mastering process, develop/tune your ears, learn about EQ techniques, compression, limiting, as well as advanced techniques such as mid/side processing and multiband dynamics, and much much more. Each week you’ll master a choice of tracks yourself and get 1-2-1 video feedback (DVR) on your work from your tutor. Courses start: 9th Jan, 5th March, 30th April 2012
We’re pleased to be running the course in association with the fantastic Waves plugins but the skills you absorb can be applied to any mastering software or hardware.
“Mastering is one of the most important stages of the production process and we’re delighted that Point Blank have gone with Waves as their plugins of choice”
Gilad Keren, Waves Audio CEO
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This clip is part of a series taken from the Audio Mastering course featuring Waves plugins. It’s been developed by Doug Shearer, the mastering engineer for acts such as Guillemots, Kasabian, and Jamelia. The audio mastering course is designed to help you make your tracks sound like the ones you hear at the club or on the radio. To get more content like this, visit the Free Courses section at PointBlankOnline.net.
Doug Shearer: OK, another approach to parallel compression, if we open our C1, we can have a much slower attack and release, a deeper threshold. We’re right in the heart of the music, with quite a low ratio. Move it there and likewise, a long release as well. We’re doing this to bring out the mid-range bass, and we’re letting all the peaks through. And so, again, we can compress reasonably aggressively. When we combine it with the original, we get some of that life back that we’ve maybe lost in our aggression, and we can blend to our tastes, basically, between the two.
We AB this to the original. We’ve definitely got back the mid-range going on there. The synth really coming out, the snare coming out, but it still sounds transparent, it doesn’t sound too compressed, it doesn’t sound distressed in anyway, if you like. Although, we’ve got quite a lot of gain reduction going on. In this way, working, we might have up to 5dB of gain reduction, more or less.