Compressors are complex tools and, like most other audio engineering tools, there are more ways to set them up ‘wrong’ than there are to set them up ‘right’. If you’re careful though, you won’t fall into these common traps:
- Too much gain reduction. You know you’ve done this when you’ve got tons on gain reduction and you’re thinking to yourself: “It sounds great but I can’t get rid of this massive click at the start of every transient.” The click is from the attack time. Not only does it sound silly, but it will rob you of your headroom. Clicks like that are similar to deep bass – they’re not very audible, but they can easily take up a lot of level. Solution: Either use less gain reduction (you probably don’t need that much!) or use a limiter instead of a compressor. Another approach is to use a limiter after the compressor. Heavy-sounding compression is often the result of fast attack and release times rather than a deep threshold.
- Using compression to fix non-dynamic properties of sound. You know you’re doing this when the sound you’re compressing has no dynamics to begin with (such as a synth bass/pad/lead). When you compare the sound with and without compression, the dynamics don’t change, but the tone or harmonic content changes. In this case, the compressor is not the best tool for the job. Solution: Listen to the dry sound and consider whether you actually need a saturator or EQ. Next time, get out of the habit of inserting a compressor on every sound without first deciding if compression is what you really need.
- Using mix bus compression as an alternative to mastering. You know you’re doing this when you’re rendering your mixdown to a file that will be burned straight to CD or encoded to MP3, and all you think you need to do is ‘make it louder’. Mix bus compression has its uses, but it’s not the right tool for achieving raw loudness. Solution: If you’re in a rush and you don’t care about quality, then use a digital limiter set to kill and call it a day. If you care about quality, either take the time to do it properly, or find someone to do it for you.
- Using mix bus compression as an alternative to working hard in mixing. Don’t be lazy! You know you’re doing this when you’re trying to use your mix bus compressor to change the sound of an individual element in your mix. Don’t use mix bus compression to address a kick or snare that is too loud – it will have unintended effects on other mix elements too. Solution: Don’t be lazy. Go back to those individual tracks that need fixing.
- Using side-chain compression to get two clashing parts to work together. This is using a sledgehammer to crack a walnut. As above – don’t be lazy! Side-chain compression can be useful as an effect, but it’s certainly not necessary for simple mixing tasks like getting vocals and guitars to work together. Solution: Use tone and depth to separate sounds. More on how to do this later.
If you can steer clear of these common mistakes, you’ll be well on your way to effective compressing!