There’s a reason you’ll find a gate on nearly every studio mixing console. While they seem to have lost some favor in the age of digital production, gates are no less valuable now than they’ve ever been. Whether you want to quickly and automatically clean up a recording or use it as a creative effect, the gate is an important tool in your dynamic control arsenal.
If you’ve tracked an instrument or vocal at home, you’ve likely noticed a vague hum and white noise droning away in the background of your recording. Some of this is fine, but as you begin to layer tracks the sounds of the room and preamp noise begin to compound into an unacceptable nuisance in the recording and must be removed when possible - namely, when the track is supposed to be silent, it should be silent. One way to go about this is to write in automation on your fader, lowering the volume whenever the instrument isn’t playing. Another method would be to toggle the mute switch when nothing should be playing.
But the far simpler solution is to take advantage of gates to attenuate a signal when it's volume gets low. Gates are a lot more versatile than an automatic mute switch, however, and provide a full range of utility and creative effects. In this guide, we’ll cover the controls you’ll need to most effectively set a gate.
threshold & floor
The threshold is a concept you’re probably already familiar with from working with compressors. Simply put, the threshold establishes the jurisdiction in which the gate may exercise its power. Unlike a compressor, however, gates start to work when a signal drops below the threshold.
The other essential gate control is the floor, which is pretty straightforward – it simply indicates the amount of attenuation that occurs when the gate is triggered, i.e. when the signal is below the threshold. Unlike compressors, gates are not so “signal-dependent”. That is, the amount of dB’s a signal is under the threshold is unimportant as gates are but a binary beast – once the volume falls below its threshold, regardless of whether it is by .1 dB or 30dB, it lowers the signal by the fixed amount set by the floor.
And so the gate’s effect is an interaction between these two essential components – the threshold and floor. Neither of them have any impact on the signal alone.
It's worth noting some gates employ a ratio, similar to the one found on a compressor, that lowers volume differently depending on how far the signal drops below the threshold. This makes the gate function as an expander, which will be a topic for another time.
hold, release, & return
At this point, you may be thinking that gates sound like a crude sculptor of sound, and you’d be right – the threshold and floor alone would result in jagged and awkward cuts. Of course, the engineers that design signal processors are aware of this and usually include a slew of tools to make the gate more functional.
One of these controls for more natural-sounding gating is hold. Hold tells the gate to do just that – hold itself open for a fixed period of time to see if any signal will cross the threshold before it closes shut. In this way, hold prevents “chatter”, the sound of the gate rapidly closing and opening, which can be really annoying. Think of it this way – an elevator waits a certain amount of time before it shuts and each time someone crosses the threshold of the elevator, the countdown to close the doors is reset. Hold works in much the same way.
Release is a similar control, but it works on an exponential ramp and eases in the attenuation as the gate closes. When the signal crosses the threshold, the volume is attenuated immediately but not by the amount specified by the floor. Over the amount of time set by the release, the volume is reduced more and more until the full amount is reached. Note that the release time will begin after the hold time is depleted, so if hold is set to 100ms and release is set to 100ms, it will take 200ms for the gate to completely close.
Another way you can prevent chatter is to set a return. The return creates a separate threshold point for closing the gate. For example, if you have a threshold of -5dB and a return of 5dB, the gate will open when the signal exceeds -5dB but when the signal falls below this point – say, to -7dB – the gate will not close, because the new threshold, the return, is set to -10dB (-5dB – 5dB).
These three controls – hold, release, and return – are crucial to effective gating. While the most obvious problem they solve is chatter, they also help your sounds make a natural exit, kind of like a realtime automatic fade.
attack & lookahead
The last set of controls looked at how the gate starts to close after a signal dips below the threshold. Now we’ll look at how the gate opens when the volume exceeds the threshold.
The first of these is attack. Attack tells the gate how long it should take to open after being closed. A slow attack will shave off the initial part of the sound that triggered it while a smaller value will open the gate very fast, ensuring the often-critical initial transient is preserved.
Unfortunately, even a very fast attack may not be fast enough, as the gate can merely make a response to a signal – that is, the threshold is crossed, the gate has to “notice” and then takes action. Digital gates have more or less solved this by using lookahead to delay the signal slightly, allowing the processor to “peer into the future” and anticipate changes in volume that will affect its signal processing.
The more natural sound will almost always be a fast attack that opens the gate quickly, but as with any processor, you’ll want to think about what you want to achieve before you implement it.
Sidechain allows the gate’s function to be influenced by a signal that is different than the signal it is being applied to. Consider all that we’ve discussed up to this point – the basic function is to open a gate when the signal exceeds the threshold and then close when it falls below. A sidechained gate bases these decisions by reading the volume of a different signal and can produce wonderful creative effects, from "tying" two sound together to arhythmic stutters.
Those are the key controls you'll find on a gate. If you enjoyed this article, be sure to check out our similar guide on compressors. Thanks for reading!