MXR Smart Gate Pro

The MXR Smart Gate Pro is a two-channel noise reduction pedal from the MXR Custom Shop. Where a standard noise gate pedal listens to one signal and mutes it when you stop playing, the Smart Gate Pro gives you two discrete channels that can be linked to quiet a stereo signal, each with its own threshold and noise-reduction settings¹. MXR's manual describes it as "Precise, intelligent noise reduction," and it is designed to sit in an amplifier's effects loop rather than in front of the amp¹.

The Pro is the bigger sibling of the MXR Smart Gate (M135), a single-channel pedal that Guitar World named its pick for beginners in its April 2026 noise gate buyer's guide, calling it "simple to use and reasonably priced"²³. The Pro keeps the Smart Gate's three-range approach to noise reduction but doubles the channels and adds remote switching¹.

A two-channel noise gate for the effects loop

The Smart Gate Pro's job is to sit between your amplifier's effect send and effect return and cut the noise your gain pedals and preamp produce. The manual's setup is a numbered process¹:

1. Run a cable from the amp's effect send jack to the input jack of Channel A on the Smart Gate Pro¹.
2. Run another cable from the Smart Gate Pro's output jack to your amplifier's effect return jack¹.

With two channels, the Pro can gate a stereo rig, or the channels can run independently, each set for a different level of noise. The Sync switch links channels A and B when you want both sides working as one gate¹. This is the main structural difference from the single-channel Smart Gate, whose manual recommends placing it last in the signal chain, just before the amplifier, to quiet a rack of noisy effects⁴.

The controls for each channel

Each channel carries its own set of controls, so the two sides can be tuned independently¹.

The Gate LEDs give you a visual check of how hard each channel is working, which is useful when setting thresholds by ear in a loud room¹.

What the Hiss, Mid Range and Full settings do

The three-position knobs choose which band of noise the gate targets. MXR's manual for the smaller Smart Gate explains the ranges in practical terms: the Hiss setting and the Mid setting are both effective on instruments with high gain midrange boosting, such as distorted electric guitars and amplified harmonicas, while the Full setting is most effective on input sources with low-end hum and buzz problems, such as AC line noise, display noise, or light dimmer noise⁴.

Reviewers of the Smart Gate found the same three ranges cover most situations. Guitar Player's buying guide wrote that "the three settings of 'full', 'mid', and 'hiss' will generally cover all uses," and described the character of the extremes⁵:

The same guide noted Hiss mode removes any trace of nasty noise⁵. Guitar World's review of the Smart Gate made the same point about coverage, saying it "is equipped with three selectable types of noise reduction to handle virtually any type of signal"⁶.

Power: 9V DC adapter

The MXR Smart Gate Pro Rack Unit runs on the included Dunlop ECB003 9-volt adapter⁷. The MXR Smart Gate Pro is powered by the Dunlop ECB-004 adapter, an 18-volt DC regulated AC adapter¹. The MXR Smart Gate and the M135 Smart Gate both run on a 9V DC power supply drawing 15mA⁴, and the Smart Gate pedal can also be powered by a 9-volt battery or a Dunlop ECB003 9-volt adapter, along with the DC Brick, Iso-Brick, and Mini Iso-Brick power supplies (not included)³.

The Smart Gate Pro is powered by the Dunlop ECB-004 adapter, an 18-volt DC regulated AC adapter¹. The plug polarity is positive on the barrel and negative on the center, the reverse of the center-negative convention most 9-volt pedals use¹. By comparison, the Smart Gate M135 runs on 9 volts DC at 15 mA and can be powered by one 9-volt battery, a Dunlop ECB003 adapter, or Dunlop's DC Brick, Iso-Brick and Mini Iso-Brick power supplies⁴³.

Connections and bypass

Each channel has true hardwire-bypass outputs, so the signal passes without the circuit when the channel is bypassed¹. The Pro also has remote switching capabilities, so it can be engaged from elsewhere in a rig rather than only at the unit itself¹.

MXR builds two companion pieces around the Pro. The Smart Gate Pro Rack Unit (M235) is described by MXR as "the big brother to the Smart Gate pedal," a noise gate rack unit with the same three selectable ranges (Hiss, Mid, and Full), true hardwire-bypass on each channel, a selectable ground lift, and power from an included Dunlop ECB003 9-volt adapter⁷. The Smart Gate Pro Foot Controller handles the remote switching from the floor; it can be powered by a 9-volt battery, a Dunlop ECB003 9-volt adapter, or the DC Brick, Iso-Brick, and Mini Iso-Brick power supplies⁵⁴³.

How it differs from the Smart Gate

The Smart Gate (M135) is the single-channel original. Its control set is one Trigger Level knob, a mode selection between Full, Mid and Hiss, and a Hi Trigger switch that extends the trigger range for extremely noisy situations⁴³. It runs on a 9-volt battery or adapter at 15 mA and uses a hardwire bypass⁴³. Guitar World's 2026 buyer's guide positions it as "the smart option for beginners," effectively a single control once the mode is chosen².

The Pro adds the second channel with independent controls, the Sync link, remote switching, and true hardwire-bypass outputs per channel, at the cost of an 18-volt-only power requirement¹. For a player with a stereo rig or a noisy effects loop that needs two gates set differently, the Pro's two channels are the point; for a simple single-chain board, the Smart Gate covers the same three noise ranges in a smaller, battery-capable box¹⁶⁵.

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