October 2024: Fractal Audio's VP4 Virtual Pedalboard has been added to the wiki.
Noise gate
Contents
Noise gate in the Input blocks
About the input gate
The Input block contains a noise gate.
On the Axe-Fx III, FM9 and FM3 this applies to each Input block and all signal that appears at an Input block is processed by the gate, whether analog, digital, or USB.
CPU usage
The noise gate in the Input block increases CPU usage, so switch it off (turn Threshold OFF) if you have no need for it.
Tweaking
At default settings the gate in the Input block already works fine. It there's still some background noise, for example from a flanger or high-gain amp, increase Ratio and/or adjust Threshold.
(Axe-Fx III) "The new noise gate in the Input block is killer. I recommend starting with default settings (reset the block) and then adjust the threshold to obtain the desired results." [1]
"The input block gate is designed for fast attack." [2]
(low threshold) "You'll kill a bit of high end with it that high. It may color the midrange a bit too." [3]
Firmware 21.02 for the Axe-Fx III:
"A Mode selection has been added allowing the user to select between “Easy” and “Advanced”. In Easy mode the number of parameters is reduced simplifying the adjustment procedure for those who are unfamiliar with the finer details of gates/expanders for guitar noise reduction applications."
Types
There are 3 noise gate types in the Input block:
Classic Expander – Basic downward expander.
Intelligent – Faster and more stable noise gate, using a proprietary noise reduction algorithm.
Noise Reducer — Reduces noise while preserving the attack of the note. It does this by using intelligent filtering to remove line noise and high frequency hiss while leaving the rest of the spectrum intact.
The Axe-Fx III, FM9 and FM3 also include EMI filtering as part of the noise gate in the Input block, see above.
The Classic and Intelligent types can achieve complete silence while the Noise Reducer type can let some sound through as it is designed to be as transparent and unobtrusive as possible.
"The Intelligent mode of the gate is more than just a gate, it includes noise reduction." [4]
"The Input Block already uses a downward expander." [5]
Gate/Expander block
Available on which products
- Axe-Fx III: 4 blocks
- FM9: 4 blocks
- FM3: 2 blocks
- Axe-Fx II: 2 blocks
- AX8: 1 block
- FX8: 2 block
Channels or X/Y
- Axe-Fx III and FM9 and FM3: 4 channels
- Axe-Fx II XL and XL+: X/Y
- Axe-Fx II Mk I and II: no
- AX8: X/Y
- FX8: X/Y
About the Gate/Expander block
The standalone Gate/Expander block allows precise control over gate settings and flexibility, because you can put anywhere on the grid and it offers side-chaining. A common position is after a high-gain Amp block.
"The self-noise of your guitar is usually greater than the self-noise of the Axe-Fx. This noise will be amplified by the amp block. For high-gain tones it is almost always necessary to use a gate to control this noise. Adjust the noise gate in In/Gte to squelch the noise." [6]
"You shouldn't use gate and noise reduction together. One or the other." [7]
Types
There are 4 types in the Gate block:
Classic Expander: Based off classic analog downward expanders. It has less chatter and tighter gating than the Classic Gate. Previously named: Downward Expander.
Modern Expander: Uses a novel approach to the envelope detector resulting in improved ballistics compared to traditional analog expanders. A “Knee Type” parameter has been added which allows selecting between hard-knee expansion and varying degrees of soft-knee expansion.
Classic Gate: Based on the classic noise gate where the gate opens when the Threshold value is exceeded and decays to the Attenuation value when below the Threshold value and the Hold timer has expired. This type offers harder gating and is useful for aggressive styles.
Modern Gate: Similar to the Classic Gate except the gate opens in a constant linear-in-dB manner. This naturally makes the attack slower as the gate first opens. It can be used for both traditional gating. It can also be used for special effects like audio swells (substitute for the Auto-Swell type in the Volume/Panner block.
"The Modern Gate is the best of the bunch but it uses more CPU." [8]
AC Line Frequency
The Intelligent and Noise Reducer gate types in the Input blocks in the Axe-Fx III, FM9 and FM3 include EMI filtering. This helps suppressing pickup noise. This requires setting AC LINE FREQUENCY in the Global Settings menu to the correct value for your country:
60 Hz = USA
50 Hz = Europe
Note: this is not the same parameter as AC LINE FREQUENCY in the Amp block.
(Axe-Fx III) "Improved Input block noise gate. When the Type is set to Intelligent (default) the noise gate now provides smart EMI filtering which reduces hum and buzz. NOTE: For best results the AC Line Frequency parameter in the Global Settings menu should be set to match the power line frequency of your country (i.e. 60 Hz for North America, 50 Hz for EU, etc.)."
(firmware Ares 12.06) "Improved performance of noise gate in Input block. Both the Classic and Intelligent types have been improved. The new Noise Reducer type reduces noise while preserving the attack of the note. It does this by using intelligent filtering to remove line noise and high frequency hiss will leaving the rest of the spectrum intact. Be sure to set the global Line Frequency to a value commensurate with the AC frequency in your country. Note that the Classic and Intelligent types can achieve complete silence while the Noise Reducer type can let some sound through as it is designed to be as transparent and unobtrusive as possible."
"The Intelligent mode in the Input Block Noise gate does dynamic lowpass filtering AND dynamic line noise filtering. For the latter to work properly you MUST set the Line Frequency to match the frequency in your country (i.e., 60 Hz for USA, 50 Hz for EU, etc.)." [9]
Noisegate Offset
The Noisegate Offset parameter in the Global Settings menu offsets the Threshold setting across all presets. This can be used to increase or decrease the threshold to compensate for varying interference levels. If the Threshold parameter in the preset is set to “Off”, the global Noisegate Offset value will have no effect. The default value is 0 dB and is set to that upon a system reset.
"When I program a pro rig, we always set the noise gate at a threshold that feels best in the studio, knowing that the global NOISEGATE OFFSET which can save you in a pinch should the rig need to be used in a noisy environment. By the way, BEFORE we had this global option, we'd often opt for a much more aggressive threshold: -65 db or thereabouts!" [10]
Parameters
Threshold
This determines how quiet the signal must be for the gate to close. See: Global Settings: Noise Gate Offset (below).
(Axe-Fx III) "The new noise gate in the Input block is killer. I recommend starting with default settings (reset the block) and then adjust the threshold to obtain the desired results." [11]
The Threshold parameter in firmware Ares and later is different from the Axe-Fx II.
"There is a 20 dB offset between the II and II." [12]
"-65 dB on AX8 = -45 dB on Axe-Fx III." [13]
Ratio
Determines how much quieter the signal will be when the gate is closed.
Attack and Release
Attack determines how long it takes for the gate to open after signal levels exceed the threshold. Keep this low to preserve the attack of first notes.
Release determines how long it takes for the gate to close. Use a slow setting for a gradual decay to prevent your notes from being clipped suddenly.
On the Axe-Fx III, FM9 and FM3 always start with default settings. Don't set Attack and Release too fast.
(Axe-Fx II) "I prefer a fast attack and slow release and a ratio around 2." [14]
(Axe-Fx II) "For guitar I recommend setting the Attack time very short (less than 10ms) and the Release time to 100-200ms. Ratio 2-3:1 and Threshold to taste." [15] [16]
(Axe-Fx II) "General rule of thumb on any gate is short attack time (<5ms) and long release time (~100ms)." [17]
(Axe-Fx II) "Typically you want a fast attack and slow release otherwise you'll get noise as the gate rapidly opens and closes when the signal decays." [18]
"A rule-of-thumb is that your release time should be 10-100 times the attack time." [19]
Tip: The Gate block, with slow attack and fast release times, can be used for automatic volume swells.
Level
The Level parameter of the gate in the Input block determines the loudness of the signal entering the grid. It still works when the gate is off and can be used to boost or cut signal strength.
Sidechain
“The sidechain filter changed in 12.03. Instead of a single bandpass it is now a highpass and a lowpass. With the single bandpass the lowcut and highcut frequencies were constrained from being greater/less than each other. gate to behave differently than it does now.“ [20]
Sidechain Select (Input block only)
You can use SCSEL (SideChain Select) to select the signal the gate is working with. If the gate is the first block in the routing there's no need to use SCSEL. If the gate is placed after other blocks in the routing, it can be useful to use SCSEL to set an optimal source signal, such as Input 1. This is similar to the way the ISP Decimator operates. This is done by creating a separate routing from the grid input into the Gate block. [21]
SideChain Select is not available on all devices.
Tips and tricks
Use the Volume block as a noise gate substitute.
