In previous issues of FOH, we’ve looked at compressors. Now it’s time to at some of the other outboard gear you have, or should be using, in your house of worship. In this month’s column, let’s take a look at “noise gates.”
Noise Gates do what they sound like they should do — they open and close. But instead of letting people in and out, they let noise in and out. The reason I am following up with a previous column on compressors with this one on gates (the common short term) is that many manufacturers incorporate them in their compressor/limiter units. Noise gate processors all incorporate "threshold, attack and release" components similar to those found in a compressor.
Threshold, Attack, Release
To review, the threshold is defined as the point were gating begins. This point is usually adjustable and determined by decibel level. In the case of a noise gate, when the decibel level drops below the preset threshold the gate kicks in. Generally, turning your threshold to the right will raise the threshold level (processing more audio signal) and to the left will lower it (processing less audio signal). A compressor processes audio signal that rises above the threshold level and gates process signal that falls below the threshold. In other words compressor and gate thresholds operate in opposite fields.
The next control attack determines how fast your device captures and processes the audio signal. This control operates in milliseconds. An example of a very fast attack would be 25 to 50 milliseconds. Personally I like my gates to be set for a fast attack time. Once the signal drops below the threshold, I want it captured. Once you get a feel for this setting I am sure you will develop your own opinion on where the attack time should be set.
Now that we have captured the signal we must release it. And that is accomplished with the release setting. Release time is also calibrated in milliseconds. A quick release time (25 to 50 milliseconds) will allow the noise gate to more closely follow the audio characteristics of the instrument being gated. I am a fan of releasing the signal quickly. Again, after a little bit of trial and error, you will determine what is the best release time for the instrument you are gating. Now that we have refreshed our minds with regards to threshold, attack and release functions, let's separate the noise gate from the compressor. Whether you have a stand-alone noise gate(s) unit or one incorporated in your compressor, all noise gates do the same thing.
Cutting Unwanted Noise
A noise gate is a dynamic processor that will cut or dramatically attenuate the audio signal passing through it when the signal drops below a preset threshold. A properly set gate will allow the audio signal from a specific instrument to pass through the gate to the mixing console unaltered. The gate will stop low-level hiss, noise and any other audio from nearby instruments from passing though the specific instruments' microphone to the mixing console.
Typically there are two types of gates on the market. On that will simply shut off the signal flow when the audio drops below the threshold. This type of gate is like opening and closing a door. It can effectively cut unwanted noise or audio but its operation can be heard. A lower threshold setting can make this type of gate sound more natural.
The next and more common type of noise gate is one that will reduce the audio signal gain by a finite amount once it falls below the threshold level. As mentioned earlier noise gate can also have attach and release controls. These knobs work the way they do in a compressor. A quick attack and slower release can make your gate operation sound more natural. But use your ears and experiment with your attack and release setting and you will find the sweet spot for each instrument you gate. Some gates will have their attack and release times preset by the manufacturer.
Rocking the House
If your house of worship rocks, you may be a candidate for some noise gates. Generally gates will not improve acoustic or worship music being performed at a low decibel level. Live microphones in a loud instrument setting can definitely benefit from noise gates. A gated kick drum mic can sound more natural and precise because the gate will not allow audio signal from other drums such as a snare or toms from entering the kick drum microphone. This would also be true with a gated snare drum mic. Eliminating other audio from entering the microphone will make the snare sound better. A noisy electric guitar amplifier can benefit from a noise gate. When the guitar player is not playing his noisy amp, a properly adjusted gate will remove all excess noise and buzzing. Worship vocal mics are rarely gated but if your worship band situation is allowing too much additional audio signal into your vocal microphones, a noise gate can remedy this.
It is possible to gate an entire mix but I have never seen this in the worship biz. You may have a compressor/limiter with an onboard noise gate in you house rack. If this is the case, you can compress, limit and gate your entire mix by connecting the let and right outputs of your console into the left and right inputs of your outboard compression device. However, it is much more common to use the insert jack on your channel strip as you will be gating one microphone and one instrument at a time.
