Like many dynamics processes, compression can be a tricky one to get right, particularly where levels are quite variable. Too little compression can leave you wondering why you’ve bothered, too much and you’re subsequently saddled with unpleasant artefacts or unwanted pumping.
Couple this with the desire to make use of a compressor’s inherent flavour and you might begin to wonder how you’ll ever get where you want to be. One very effective technique is to stop trying to achieve multiple outcomes from one processor and instead use two or sometimes more compressors in series.
Serial compression allows us to play to the strengths of each processor. We could, for example, try combining the glue effect of an opto compressor with the transient modification and distortion of a FET. Or maybe experiment with the harmonic distortion of a valve design and the predictability of a VCA. Or we could simply use one compressor to smooth out levels in combination with another that can grab peaks. In most situations we are also spreading the overall gain reduction, and this is ideal in more critical scenarios such as mastering, where we may not want the audio to actually sound processed at all.
Of course using multiple compressors then requires us to decide which order to put them in. Usually the required task will help us decide. That said, creative techniques like this are always open to interpretation, and it’s often worth trying different orders. Finally, serial compression isn’t a technique that’s suited to every application. What’s more, although it can be a good way to handle tricky levels, we wouldn’t advise its use when recording, as setting multiple thresholds can be fiddly. Ultimately, serial compression can be a highly fruitful technique at the mixing stage when you have plenty of time to properly finesse settings.