Tools of the Trade: Dynamics 1

Dynamics are an interesting part of mixing. Many people mix without any dynamics units but I find that it actually makes the process a bit easier. First we start with expanders. An expander is a compressor with the control logic inverted. Instead of attenuating signals that overshoot a set threshold it attenuates signals that fall under a given threshold. Expanders work on either a range or ratio function. The ratio is much the same as on a compressor, and most factory set ranges are usually 2:1. Range value expanders are set in decibels. So setting a range to 7dB at a -5dB threshold means that anything under -5 will be automatically attenuated by 7dB.

Gates take the range and it sets it at infinity. Think of a gate as a volume-sensitive mute button. Any signal under the threshold will be cut from passing and only silence remains. Gates are great on drums where one often has to EQ the bleed out of the microphones before you think about EQing the drum itself. The channels that benefit greatly from this are the toms, the snare and kick. Its also great for tightening up the bass guitar, guitar amps that hum, and especially vocals on a noisy stage. Drawmer makes excellent gates. I don’t know a professional recording studio that doesn’t have at least a pair.

However, even Drawmer is being overshadowed by the precision and power of the gates on digital consoles as any VENUE users will know. So if an expander is a compressor with the control logic inverted, what is an expander with it’s control logic inverted again? Nope your wrong, it’s called a Ducker. A ducker attenuates sound that goes over the threshold, which is an expander in reverse. Don’t be fooled however. A ducker is not a compressor. A compressor is shaving audio off the top bringing it back toward the threshold while a ducker is like pulling a fader down, beyond the threshold. A ducker attenuates audio beyond the threshold into even the quieter bits of the audio. Every ducker I’ve seen is governed by a range value (decibels). I don’t know why duckers aren’t that widely used outside the broadcast world. Perhaps it’s because they are too powerful, and they have to compete with compressors which are more popular dynamics units.

Anyone care to guess what a ducker is with it's control logic inverted is? I'm not sure but I have a feeling it's something like an upwards-expander. Upwards expanders are expanders that raise the level of signals that overshoot the threshold, making sounds more transient and lively. The only analogue hardware upwards expander I've ever seen is the SPL Kultube, all the rest are digital algorithms.

My next post will deal with compressors, limiters, and multi-band compression.