MID/SIDE AND MULTIBAND MAGIC
>Mid/side and multiband processors can be very useful for everything from fixing tricky issues in the mix, through to adding some creative flair when EQing – but what are they all about?
MID/SIDE PROCESSING
Well, mid/side processing is derived from the microphone recording technique of the same name, which was invented way back in the 1930s by pioneering recording engineer Alan Blumlein.
Instead of using two mics in an XY configuration to capture stereo information, one cardioid mic is used to capture the mid (mono) part of the signal, while a figure-of-eight mic that’s aimed 90 degrees away from the source sound captures the (side) stereo ambience. Once these signals have been put through a mid/side matrix, you then have a fully monocompatible stereo recording, with the ability to adjust the amount of stereo width by increasing the side channel’s volume.
Modern mid/side-enabled processors allow us to split a stereo signal into its mid and side components, before processing them separately and combining them back into a stereo signal. This technique is used heavily by mix and mastering engineers as it, for example, lets you remove the sub bass from the side channel with an EQ filter when mastering for vinyl, or de-ess the mid and side channels of a ready-mixed stereo vocal stem independently, so that excessive mono sibilance doesn’t make the processor also overprocess the information in the stereo spread.
If you like the sound of mid/side trickery, you can turn any unlinked dual mono processor you like into a mid/side-capable unit easily and quickly by placing Voxengo’s fantastic (and free!) MSED before and after the processor, with one instance set to encode the sound to mid/side, and the other set to decode back to stereo. You can then use the two components of your processor to independently process the signal’s mid and side, which can be great for beefing up side heavy reverb/delay tails with compression, without touching the mid for example.
MULTIBAND PROCESSING
Meanwhile, multiband processing works by splitting the incoming signal into multiple bands using an internal crossover, allowing you to process each band independently of the others, before the processor then sums the bands back into one cohesive stereo signal.
Due to the signal being split using several filters before being recombined, multiband processing can add unwanted artefacts to the signal, making it traditionally something that’s used by engineers as a last resort for fixing awkward issues such as an overly loud hi-hat in a single drum loop, applying light compression to uneven sub bass frequencies without compressing the entire bass, or pulling down on boxy mid frequencies in a vocal take without affecting the low or high frequencies – great for sharpening up those muddy rap vocals recorded in a small booth.
However, modern multiband processing has come a long way, and generally has a minimal impact on the integrity of the signals passing through it. Additionally, there’s now a huge amount of more creatively biased multiband processors available, including multiband saturation/distortion plugins such as Fabfilter’s brilliant Saturn (great for crunching up your highs, whilst leaving the bass well alone for example) and even plugins such as Blue Cat Audio’s MB-7 Mixer 2, that allow you to split your signal into various bands, before placing your own choice of external plugins on each – multiband reverb or delay, anyone?
Now we’ve been through some of the technical details of how mid/ side and multiband processing works its magic, let’s look at some practical demonstrations of how you can harness the power of these processors in your own studio.