Expanders and gates are an integral part of music production. However, time and time again I see students implementing them poorly.
The first decision that you should make is whether you need to use one in the first place. Expanders and gates are less important than they used to be, this is because of the extended functionality available in modern DAWs. In a DAW it is simple to splice, crop, cut regions of audio or automate sections. Extended tools are available in some DAWs which make it even easier to manipulate sections of audio such as clip gain and strip silence macros.
In practice doing these tasks offline in a DAW often gives you more control, flexibility and precision. I find that this eradicates my need for an expander/gate 90% of the time.
Despite the advantages of using a DAW to achieve these effects. There are still times I prefer to use expansion/gating:
- For kick and snare drum,
- For side-chaining purposes,
- To reduce noise accumulated from many instances of analogue modelled plug-ins (when there is no parameter to turn the noise off).
So how do people mess up using an expander/gate? To find the answer, let’s examine the case of using an expander/gate on a kick or snare drum (which happens to be my usage of them 90% of the time).
In many students mixes there are these horribly tight and choked kicks and snares. Of course, it is important to reduce the level of bleed but removing ALL of the bleed almost always comes at too great a cost:
- Loss of too much sustain, space and ambience from the drum itself.
A very unnatural cutting off of other elements of the kit (particularly cymbals).
- Usually, it is much better to be lighter with them and not compromise the tone of the drums sustain too much, read: expansion NOT gating. You would be surprised what a difference just 10dB of reduction of bleed can do when that’s stacked up on all the kick and snare mics!
Setting an Expander/Gate on Multi-Track Drums
A classic way of setting an expander gate to reduce bleed (particularly on drum shells) is to work backwards from extreme settings. The rationale is simple, by setting the expander/gate so that it acts as a very hard gate (mutes the signal once it passes below the threshold) you can more easily find the best threshold so that the gate is triggered by every hit of the element you wish to open it but not any of the bleed you wish to remove.
This process requires you to begin with very fast attack and release times, so that it just sounds like a short ‘clicky’ sound when the gate opens, setting the expander/gate this way will also allow you to easily hear if the threshold of the gate is set too high and will fail to open on some of the parts you wish it not to remove. From these extreme settings, you can loosen the release and/or range so that it regains a more natural feel.
Here is this process in some easy steps:
- Set the expander/gate so that it has the fastest attack and release times and that the signal is muted once it goes below the threshold (-∞:1). The threshold should be at its lowest position so that it is always open,
- Slowly increase the threshold until the expander/gate on triggers on the intended hits but doesn’t miss any. You should be hearing each hit but will be unnaturally choked/clicky sounding,
- Relax the release knob to taste, so that it lets more of the body of the sound through. The amount you increase the release by depends on the genre, for instance, metal/hard rock is likely to be much shorter than jazz,
- Finally, lower the range to taste so that it lets the required amount of bleed through. Often in more acoustic or natural genres, like folk or jazz, some level of bleed between drum close mics are often advantageous and you might only want to reduce the bleed a little bit, in other heavier genres you might find more of a harder gate more appealing.