Noise gate

Available on which products

Noise gating is available on all Fractal Audio's processors as part of the Input block and standalone Gate block.

Information about noise gates:

• Noise, fizz, crackle, sizzle, intermodulation, crossover distortion
• Wikipedia's Noise gate article

Noise gate in the Input block

About the noise gate in the Input block

The Input block (VP4: input section) contains a noise gate.

On the Axe-Fx III, FM9 and FM3, this applies to each Input block and the entire signal that enters an Input block is processed by the gate, whether analog, digital, or USB.

Channels or X/Y

• Axe-Fx III and FM9 and FM3: 4 channels
• VP4: no
• Axe-Fx II: no
• AX8: no

Types

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 current processors 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.

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[1] The Intelligent mode of the gate is more than just a gate, it includes noise reduction.

[2] The Input Block already uses a downward expander.

CPU usage

The noise gate in the Input block increases CPU usage, so switch it off (turn Threshold OFF) when 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.

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[3] 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.

[4] It's is not recommended to set both attack and release to fastest values. For "metal" start with attack around 2ms and release around 100ms. Try a ratio of 3-4. Adjust threshold to taste. If you turn attack and release all the way down the detector will "chatter" and modulate the input. If attack is set short, then release should be long and vice-versa. Most dedicated noise gates have quite long release times. I.e., a Decimator has a nominal release time of around 330ms.

[5] The "gate" in the input is downward expander. As such, hysteresis doesn't really apply. If you want a gate with hysteresis use the "Classic Gate" in the gate block. The hysteresis is not adjustable though. It's fixed at 3dB.

Gate/Expander block

Available on which products

• Axe-Fx III, FM9, VP4: 4 blocks
• FM3: 2 blocks
• Axe-Fx II: 2 blocks
• AX8, FX8: 2 blocks

Channels or X/Y

• Axe-Fx III, FM9, FM3, VP4: 4 channels
• Axe-Fx II XL, XL+, AX8, FX8: X/Y
• Axe-Fx II Mk I, II: no

About the Gate/Expander block

The standalone Gate/Expander block allows precise control over gate settings and flexibility. You can put anywhere on the grid and it offers side-chaining. A common position is after a high-gain Amp block.

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[6] 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.

[7] You shouldn't use gate and noise reduction together. One or the other.

Gate block diagram

Types

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.

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[8] The Modern Gate is the best of the bunch but it uses more CPU.

Gate block position on the grid

You can put the Gate block anywhere on the grid. Many high gain lovers place it after the Amp block.

Parameters

Global Settings: AC Line Frequency

The Intelligent and Noise Reducer gate types in the Input blocks in the Axe-Fx III, FM9, FM3 and VP4 include EMI filtering. This helps suppressing pickup noise. This requires setting AC LINE FREQUENCY in the Setup 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.

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From the v1.09 release notes:

[9] […] 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.).

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.

[10] 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.)."

Global Settings: Noisegate Offset

The Noisegate Offset parameter in the Setup 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.

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[11] 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!

Threshold

This determines how quiet the signal must be for the gate to close. See: Global Settings: Noise Gate Offset above.

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[12] 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.

[13] (threshold at zero) "You'll kill a bit of high end with it that high. It may color the midrange a bit too. The Threshold parameter in firmware Ares and later is different from the Axe-Fx II.

[14] There is a 20 dB offset between the II and II.

[15] -65 dB on AX8 = -45 dB on Axe-Fx III.

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. The default of 2.0 ms is a good starting point, according to the manual.

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.

The Gate block, with slow attack and fast release times, can also be used for automatic volume swells.

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[16] I prefer a fast attack and slow release and a ratio around 2.

[17] 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.

[18] General rule of thumb on any gate is short attack time (<5ms) and long release time (~100ms).

[19] 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.

[20] A rule-of-thumb is that your release time should be 10-100 times the attack time.

[21] The input block gate is designed for fast attack.

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

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[22] 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.

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. [23]

SideChain Select is not available on all devices.

Tips, tricks and troubleshooting

Factory presets

The Gate block is present in a couple of factory presets. Search the Factory presets page for gate.

Use Volume block for gating

Use the Volume block as a noise gate substitute