22 Jan MULTIBAND COMPRESSION
Multiband compression divides the frequency spectrum into different sections, or bands, so that each has its own unique compression settings. This allows a longer attack time for the low band of that bass drum to punch through, while keeping a shorter attack time in a higher band to keep the guitar in check. By using a multiband compressor, it is possible to closely tailor the compression to the different elements in a mix and compress the recording more transparently than with a standard single-band compressor.
Most multiband compressors feature either 3 or 4 different bands. Since the crossover frequencies define the range of frequencies contained in each band, getting them right can have a big impact on the effectiveness of the compression. Many multiband compressors have a solo function to focus on one band at a time — this can be very helpful when setting the crossover frequencies by revealing exactly what each band contains. Additionally, soloing individual bands can be helpful when setting attack and release times to make sure the transients in each band are shaped as desired.
Keep in mind that the frequency distribution will likely not be even in the recording being mastered, and the threshold — or amplitude at which the compressor begins compressing — for each band may be quite different. Compression ratio however, will often remain rather similar between the bands, or the compression could change the balance of frequency information and instruments in the mix. Most multiband compressor plugins will have different presets to try out, and they’re often a good jumping-off point to test out different compression thresholds and ratios.
Since the crossover frequencies define the range of frequencies contained in each band, getting them right can have a big impact on the effectiveness of the compression.
As with any kind of audio processing, it is important to listen to exactly what changes in a mix when the processing is active. Bypassing the plugin and A/Bing with the unprocessed audio can be very helpful for this. Multiband compression is one of the most powerful processing techniques currently available to audio engineers and when it is used effectively it can achieve great results. That said, when it is used incorrectly, it can cause more damage than good.