Recently Mike Wells posted a blog article about stereo bus compression during mixdown. We’ve decided to re post this article as we have also noticed more and more engineers incorporating this into their mix process. You can find this article, as well as other great articles on mastering at Mike Wells website: www.mikewellsmastering.com.
- John
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This article is the result of our 05/15/2010 Audio Outreach seminar held at Leo’s Pro Audio in Oakland, CA.
Our focus is for those new to audio engineering and looking to “fatten-up” their mixes with buss compression. This article takes a different slant on the subject of compression (we’re not going to talk about settings), but rather we delve into the topic of techniques to help you in learning to hear compression envelope & artifacts to help you achieve your best mix.
So let’s begin with Buss Compression: What are you hearing?
Introduction:
Why use buss compression?
1) It sounds great (when used correctly)
2) It can do great things to your mix (add the “glue”, “fatness”, “punch”, etc)
3) It makes your mix LOUDER and makes your clients happier when they are reviewing mixes before mastering
The caveat to all this greatness, however, is that if you can’t hear the envelope of the compressor then all your efforts are in vain. Without the ability to hear the envelope, you can end up with compression artifacts such as pumping, breathing, ducking, etc. Sure, some musical genres rely on compresion artifacts for effect (House is well known for the ducking effect on the kick with the mix breathing after each kick, etc), but if you’re not intentionally going for an effect, those artifacts will show up later in mastering and work against you. Read on.
Navigating today’s terrain:
Let’s face it, mix engineers are under ongoing increased pressure to deliver louder mixes to clients (just as mastering engineers are). Clients want their mixes to hit them like the finished master, and many younger engineers tell me they are applying more buss compression to compensate for this phenomena.
You already own the tools to tune your ear:
You can never be “too good” at hearing compression effects. Here are two tips that help me every day:
1) Try monitoring at low levels
I find it easier to hear compression at lower volumes. Your mileage may vary. For me, there’s less gain competing for my attention, and I can focus on hearing the envelope. Give it a try. Focus on the movement of the music around the beat. Is the music “moving forward” or “moving backward” against the rhythm of the music? Check your settings. The attack may be grabbing the kick to quickly, or the release may be too long therefore conflicting with the next attack.
2) Try a M/S monitor matrix
A Mid/Side monitor matrix on your stereo buss can eliminate many elements competing for your ears’ attention and help you hear compression artifacts. To do this, mono your stereo buss, then phase-invert one channel against the mono mix and you are left with the side channel. Now sit back and listen. Another benefit of this technique is hearing gates with reverb in your side channels. If you are using compressors & gates on individual channels along with compressors on groups (drums for example), adding another compressor to your buss can complicate your ability to hear and discern what is going on and monitoring in M/S can assist your ability to “decode” your mix a bit.
Once you detect you are hearing envelopes moving in an undesirable way, start bypassing compressors starting with your buss compressor, then groups, then look at your channel comps. Step back and listen again. This attention to detail will pay off in mastering. Read on.
Suffering the risks:
While it’s widely known that mastering will increase the overall loudness of your mix, it is also very possible that undesirable compression artifacts will be further highlighted by the mastering process, which can lead to “there’s pumping in my master!” when in reality there is pumping in the mix, it’s just LOUDER now. When encountering a mix with severe compression artifacts, commonly a mix will be returned and the engineer consulted with. If deadlines are at hand, remixing is not available, etc, and mastering must proceed, you may find yourself having a conversation with your mastering engineer where he/she is informing you of “what’s possible”. Never a great situation to be in, but it happens.
How can you take action?
1) Spend time, more time, and more time tuning your ear to hear compression. Try different techniques like the ones mentioned above and seek out new techniques.
2) Consult with your mastering engineer to check your mixes. A professional mastering engineer should be willing to help you with your mix review.
3) Try using a peak limiter on the mix for “Client Refs”. Meaning if the client is only concerned with loudness when they take their mix ref CD home (away from your studio), strap a peak limiter across the buss and add some gain via peak reduction/makeup gain. The client is happy and you are not making sacrifices.
Conclusion:
The more complex the mix, the more compressors used throughout the mix on tracks, groups, the more you challenge your ear to discern what you ARE hearing and what you THINK you are hearing. Slowing down and focusing on the details of your mix compression will pay off in the long run for the mix you’re working on now, and each mix you do in the future.
Some additional articles on buss compression:
SOS on Buss Compression: http://www.soundonsound.com/sos/may08/articles/mixcompression.htm
Charles Dye article: http://www.gearslutz.com/board/tips-techniques/170189-mix-buss-compression-charles-dye.html
Fab Dupont video tutorials on compression: http://www.sonnoxplugins.com/pub/plugins/fab-videos.htm
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This document is Copyright 2010, Mike Wells Mastering except where otherwise noted. It has been reproduced with permission from Mike Wells and may not otherwise be reproduced in any manner without the permission of the copyright owner.
