078 – Dynamics Processors 101: Gates
Gates are especially effective on percussion and other transient sounds.
Written by Scott Adamson
What Is a Gate?
Dynamics are a fundamental part of music. Music that has much quieter parts along with much louder parts is said to have a wide dynamic range.
As live sound engineers, we generally don’t want to interfere with the natural dynamics of a song too much, but sometimes they need to be tamed. To accomplish this, we use dynamics processors, a family of software or hardware equipment designed to modify the dynamics of an audio signal in various ways. Common examples include gates, expanders, compressors, limiters, and de-essers. Along with EQ, these are essential mixing tools that we use in almost every mix.
Over the next few weeks, we’ll discuss the in and outs of several of these important tools, one at a time.
First, let’s talk about gates.
Gates are designed to cut out or attenuate signals below a set threshold. They’re used to shape the transients of a signal, which is especially useful for drums and percussion instruments, and help eliminate unwanted noise.
Gates have a lot of different settings, but there are five key parameters that are particularly important to understand: threshold, range, attack, hold and release.
The most important setting on any dynamics processor is the threshold. This determines when the processor kicks in and starts affecting the signal. On a gate, it’s easiest to think of it as the point of opening and closing. As soon as the signal crosses the threshold, the gate will open and the signal can pass. When the signal drops back down below the threshold, the gate closes and the signal will be cut or lowered depending on the range.
The range determines how much the signal is reduced. This is sometimes called depth, as well. If the range is set to 20dB, then the signal will be reduced by 20dB whenever it’s below the threshold and the gate is closed. If you want the gate to completely block the sound when it’s closed, set the range to 100dB, or whatever is the highest setting on that particular device. Most of the time, however, using a more moderate range can help the processing sound a bit more natural.
Gates also have attack, hold, and release times. These determine how quickly the gate opens, how long it stays open, and how long it takes to close, respectively, and they can really affect the sound.
A quick attack time means the gate will open as soon as the signal crosses the threshold. This is good for short, transient sounds like the smack of a snare drum. Increasing the attack time means the gate will open more slowly. This can potentially cut off the top of those quick, transient sounds, so when working with drums, it’s good practice to keep the attack time on the faster side, unless you have specific reason to increase it.
Once the gate is open, we keep it open with a designated hold time. After the hold time is done, the gate will close according to the release time.
It’s important to take some time and experiment with the attack, hold, and release times. They often determine whether the gate functions slowly and subtly or in a fast, even choked sounding manner.
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Especially with loud music, gates serve another important purpose — cutting stage bleed! This refers to that pesky lack of isolation that often occurs onstage, when you hear one instrument through the microphone of another instrument. In the studio, there are several ways to keep those microphones isolated, but it’s much harder to achieve in live settings.
If you’re hearing an electric guitar through a rack tom mic that’s five feet away, it’s not going to sound very good. That loud guitar might be causing the drums to vibrate, which can cause a low rumble coming through the mic. Using a gate will let the loud drum sound through and then the gate will close and all the extra noise won’t be heard.
This can serve as a quick fix for a buzzing channel as well. If you have a ground loop or if there’s a noisy amp on stage, it’s best to try and fix those problems at the source. But if you’re in the middle of a show and there’s no time to troubleshoot, inserting a gate can be an easy solution. Sometimes the fast workflow of live music makes us solve problems as quickly as possible with whatever tool we have immediately available.
