The basics of gates and expanders for mixing and sound design
Gates and expanders work in the opposite way to compressors, instead of decreasing peaks they work below the threshold.
In a previous tutorial, we discussed compressors and the theory behind how they work, now we’re looking into gates and expanders, which work with similar parameters although doing completely different things.
While compressors work on audio above the set threshold, gates and expanders work on audio below the threshold. The obvious and most common use for these types of processes is to reduce background noise from vocal recordings.
It’s particularly helpful when applying heavy processing to a signal which has background noise in it, distortion or compression may bring out that noise – while a gate or expander before that will certainly clean up the signal.
An expander is a great tool to tame the reverb tail of a signal, in sound design if you want to create a big sound without having to deal with a long reverb tail, put an expander after the reverb in the signal chain.
This will allow the tonal characteristic of the reverb to come through, without the actual reverberation. Using a gate in this example may be too drastic.
What are the actual differences between gates and expanders?
The difference between a gate and an expander is similar to the difference between a compressor and a limiter. A gate removes all audio below the set threshold point, while an expander allows you to dial in the amount of overall reduction.
This means that a gate is a lot more of a drastic audible different, and often results in a less musical sound. It’s great for cleaning up speech and voice-overs, but for sound design, I generally opt for an expander.
It’s important to remember that like how most compressors allow you to limit; some gates can be set to expander mode – in the Kilohearts Gate, this is done with the “range” parameter.
For an in-depth explanation on all of this, check out this week’s tutorial video here: