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Information about the FM3 may be incomplete or wrong, it's being worked on.

Noise gate

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Revision as of 19:07, 27 March 2020 by Yek (talk | contribs) (EMI filtering)
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Gate block.png

Input block

About the noise gate in the Input block

The Input block contains a noise gate. On the Axe-Fx III and FM3 this applies to each Input block.

(Axe-Fx III) "Each input block has a built-in gate." source

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.

Configuring the noise gate

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.

In the Axe-Fx III and FM3, all signal that appears at an Input block is processed by the gate, whether analog, digital, or USB.

(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." source
"The input block gate is designed for fast attack." source

EMI filtering

The Intelligent and Noise Reducer gate types in the Input blocks in the Axe-Fx III and FM3 include EMI filtering. This helps suppressing pickup noise.

This requires setting AC LINE FREQUENCY in the Global menu to the correct value for your country:

60 Hz = USA
50 Hz = Europe

(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.


There are two types of noise gate in the Input block:

Classic – a basic downward expander

Intelligent – a faster and more stable gate, using a proprietary noise reduction algorithm

The Axe-Fx III and FM3 also include EMI filtering as part of the noise gate in the Input block.

"The Intelligent mode of the gate is more than just a gate, it includes noise reduction." source
"The Input Block already uses a downward expander." source

Gate/Expander block

About the Gate/Expander block

The standalone Gate/Expander block allows precise control over gate settings, such as Sidechain Select, and flexibility, because you can put anywhere on the grid and it offers side-chaining. A common position is to add it after a high-gain Amp block.


Downward Expander: in firmware Ares 12 and later. It has less chatter and tighter gating than the Classic Gate.

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.

Available on which products

  • Axe-Fx III: 4 blocks
  • FM3: 2 blocks
  • Axe-Fx II: 2 blocks
  • AX8: 1 block
  • FX8: 2 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." source

Channels or X/Y switching

  • Axe-Fx III 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

There's no MIDI CC available for Gate/Expander X/Y switching on the Axe-Fx II.


Parameters table

Parameter Axe-Fx III / FM3 Axe-Fx II AX8 / FX8
Type (Input block only) yes
Threshold yes
Ratio yes
Attack Time yes
Release Time yes
Hold Time yes
Sidechain Source yes
Low Cut, High Cut yes
Global > AC Line Frequency (Input block only) yes no no


(firmware Ares 12.03) “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.“ source


This determines how quiet the signal must be for the gate to close. See: Global 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." source

Note: the Threshold parameter in firmware Ares is different from the Axe-Fx II.

"There is a 20 dB offset between the II and II." source
"-65 dB on AX8 = -45 dB on Axe-Fx III." source


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 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." source
(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." source source
(Axe-Fx II) "General rule of thumb on any gate is short attack time (<5ms) and long release time (~100ms)." source
(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." source
"A rule-of-thumb is that your release time should be 10-100 times the attack time." source


The Level parameter of the gate determines the loudness of the signal entering the grid. It still works when the gate is off and can be used to boost of cut signal strength.

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. source source source

SideChain Select is not available on all processors.

Global menu: Noisegate Offset

The Offset parameter in the Global 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 Offset will have no effect. The default value is 0 dB and is set to that upon 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!" source

Global menu: AC Line Freq

Available on the Axe-Fx III. And FM3? @@

This helps the gate in the Input block to suppress EMI filtering. Set it to the correct frequency for your country.

Note: this is not the same parameter as AC LINE FREQUENCY in the Amp block.

More information about noise gates

(Axe-Fx II) "On the Ultra I would use the gate on high gain patches but I find I don't need it now. I did some measurements and the II is at least 10 dB better SNR." source
"There are noise "reduction" techniques but all alter the desired signal in some way. Noise gates are among the most useful for our particular needs. Digital cameras use various techniques based on the statistics of the image (i.e. if an area of the image is monochromatic heavier filtering is applied). The Intelligent gate in the Axe-Fx uses some crude statistical processing where the statistics are based on the typical stats of a typical guitar. IOW, noise reduction is destructive. You can't beat the laws of physics. So you can't remove noise without somehow altering the original signal." source
"The amp model doesn't add noise, it just amplifies it." source
"To get the best noise performance it is important that the Instr In trim is set correctly in the I/O > Input menu. Set this as high as possible without clipping the input." source