Many people—especially somewhat less tech-savvy producers and musicians—rely heavily on presets for the various processors they employ while mixing. In and of itself, this is not a bad thing, depending on the type of processing. An EQ preset labeled “fat kick” can probably be depended on to add some thump and boom to any kick it’s used on, and a Delay preset labeled “Vocal Slap Echo” will most likely contribute a very similar effect to most vocals. But Compression (or any Dynamics processors) can be another story.
Unlike with some forms of processing, Compression is dynamic—the precise effect you get with a particular set of values is based heavily on the level of the incoming audio signal. Unfortunately, this is one thing the person who created the preset couldn’t have anticipated reliably—in the real world, recorded levels may vary considerably. This variation may be enough that the assumptions made when the preset was created—how strong the overall effect would be, how it would dynamically affect specific aspects of a typical performance—might not hold at all when that preset is applied to a recording with notably different characteristics. Different overall level, different musical dynamics—these and other potential variations can result in that preset not having the intended effect, instead producing too much or too little compression, or simply not getting the job done as well as possible. Optional : This video, from the Audio Mistakes series of courses, explores the issues related to the potential over-reliance on presets when it comes to Compression..
Compression is already one of the most difficult processors in the recording and mixing toolbox to really get a handle on, and it pays to devote more energy to getting to know the ins & outs of how compression, and compressors, actually work their magic, rather than putting that energy into amassing a collection of presets that may be considerably less reliable than other processors’. This is one case where it’s far better to master the tool itself—then you’ll be ready for anything.