Hello and welcome to this week's article! Today we're going to talk about Noise Gates!
When we record an audio from a souce, a microphone or straight with the jack into the audio interface, we may have some unwanted noise, generated for example by the hum of the pickups (especially the single coil ones), the quality of the cable, and every other ring on the chain that brings the sound into the Daw.
Let's start by saying that there are different types of "noise": Hiss (which are the frequencies that produces sibilance), Hum (which is the low background noise), Clicks and Crackles (which are the snappy sounds sometimes presents when digitizing vynil recordings, or when a source goes into peak, distorting the signal) and the Ess frequencies, produces by the sibilance of the human voice.
The noisegate usually works by selecting the typical frequencies that we want to remove (for example the hiss frequencies, in the case of the DeHisser), and once they occour, heavily compressing them, lowering their level to silence.
So we're talking about plugins that are both Equalizers and Gates (a Gate is a Compressor that works on the opposite way: when a signal is below a certain threshold, instead of boosting it, it brings it down to zero decibel).
Also Gates are used when recording an acoustic drumset, to remove unwanted bleed of other drum parts on a microphone (e.g. to remove the snare sound from the kick microphone).
Many commercial noisegates (like Waves, Sonnox or Izotope) features a "Learn" function: you play a part of the track where only the noise you want to remove is hearing, and the program will remove it from the whole track leaving the other frequencies untouched. This function is featured by some free plugin too, as you can see on the list below.
Focusing on guitar sound, the main issue here is the low background noise, or Hum, generated by the pickups and sometimes by the cable too. We need to clean the sound before entering in the amplifier, or, especially if we use the distorted channel, the noise will be distorted and amplified too, resulting in a strong hum and feedback.
If we are recording an amplifier by Microphoning it, we must use a Hum remover OR just manually cut away the silence parts that feature only noise, retaining the full harmonic richness of the played parts.
If we are recording straight to the interface using Virtual Amp Simulators, instead, we can use a Noisegate BEFORE the virtual amp, and before the eventual virtual Overdrive that boosts the amp.
Many DAWs today features a bundled Noisegate that eliminates the hum, but if your bundled noisegate is not good enough or if it's completely absent, here's a selection of the best free Noisegates:
- GVST GGATE - One of the most used ones, very simple.
- 7AMP NOISE GATE - One knob gate with Learn function: you simple hold your guitar strings for a second, or keep your microphone in silence, allowing the plugin to study noise pattern, then you set filtering level.
- REAGATE - the free Gate from the Reaper Daw
- FLOORFISH - A versatile multi-purpose Gate, with Learn function.
- How to use a Noisegate to remove unwanted background noise or microphone bleed: Let's load a noisegate on the track we wish to "De-Noise", and set the Threshold control wery low, so that no signal is below it, and therefore there is no gating.
Now raise the Threshold control until only the hum is gated, and adjust the attack and release control in order to decide how fast the Gate should kick in, and for how long it should be active. It's as simple as that, just remember, when you use it to clean up your guitar tone, to adjust it with your distortion on, or the hum will be almost inaudible.