Noise Gates

Noise Gates are a very useful to when engineering sound. They can be used in a variety of situations to help control the signal and only allow the desired music or sound to be heard. What is a Noise Gate? A Noise Gate is an expansion device that allows signals through the channel only if it is above the set threshold. For example: a closed noise gate will reject the quiet sounds, but as the signal level increases, the gate will open and allow the signal to pass through the channel. Once the signal level falls back below the desired level, the gate will close again and no longer allow the signal down the line. Here are some great situations where you can use a noise gate.

Put a noise gate on a noisy guitar amp. When the guitar is being played, it is loud enough to cover up any noise the amplifier is making and there are no problems. But, as soon as the guitarist stops playing, the microphone will be picking up the hum of this noisy amp. If possible, you want to avoid getting this annoying hum into your mix. Putting a noise gate on this channel will block out the hum, but open up when the guitarist is playing because the source is now louder then the set threshold.

Another great place to use a noise gate is on a drum set. Multiple mics are usually used while recording drums. When mics are close together they can start to blend the sound of the drums because they can’t focus and one specific instrument. A gate can be placed on each of the drum mics to prevent leakage and help to focus on each individual drum. At the same time, you don’t want a noise gate on the over head mics of a drum set. You want them to pick up the cymbals and overall sound of the kit.

You can use this same technique and apply it to an entire live band. You place a mic on each musician, and use the noise gate to block leakage from the other instruments. In this situation, you might not want the gate to close completely. Have it stay open just a little bit so it only reduces the leakage by 10 or 12 dB and it will help the mix to sound more natural. Its kind of like turning down the microphone when its not being used, and turning it back up only when there is music right in front of it.