MXR Smart Gate Pro Rack Unit

The MXR Smart Gate Pro Rack Unit is a noise gate in rack form, made by MXR under Dunlop. MXR describes it as the big brother to the Smart Gate pedal, carrying the same noise reduction in a unit built for rack systems rather than a pedalboard¹. Like the pedal, it gives you three selectable ranges, Hiss, Mid and Full, so you can match the gate to the kind of noise your rig produces¹.

A noise gate works by muting the signal when you stop playing, so hum, hiss and rack noise stay silent between phrases. Where a pedal sits on the floor in your signal chain, a rack unit like this one is designed to live in an effects rack, with a companion foot controller available for switching it from the floor².

What it is and where it came from

The Smart Gate line began as a pedal. The MXR Smart Gate (M135) is a noise gate pedal with a hardwire bypass, a precise threshold trigger and three selectable types of noise reduction³. Dunlop's own history of MXR counts the Smart Gate Noise Gate among the pedals that have become modern classics⁴. The rack unit takes that circuit into rack format: MXR says the Smart Gate Pro Rack Module features the same noise reduction as the pedal¹.

The Smart Gate Pro pedal, a separate two-channel product, shows how the Pro format expands on the original. Its manual describes precise, intelligent noise reduction with remote switching capabilities, and its setup instructions point at the same use case the rack unit serves: plug it into your amp's effects loop, running a cable from the amp's effect send jack to the input jack of Channel A, and another from the output jack back to the amplifier's effect return jack⁵. The M135 pedal's manual gives related placement advice for quieter rigs: to quiet a rack of noisy effects, place the Smart Gate last in the signal chain, just before the amplifier⁶.

Ranges and controls

Both the rack unit and the pedal share the three-range approach. On the rack unit, MXR lists three selectable ranges: Hiss, Mid, and Full¹. The Smart Gate Pro pedal's manual describes the same choice as three-position knobs selecting the type of noise reduction for each channel: Hiss, Mid Range, or Full⁵.

The ranges are not just labels. Reviewers who have used the Smart Gate's modes describe real differences in feel. GuitarPlayer's reviewers wrote that "Full mode offers a really dynamic, quick gate that snaps close and produces a tight sound that is ideal for chugging," while Hiss mode removes any trace of nasty noise⁷. On the pedal side, the M135's controls include a NOISE BAND CUT switch that selects the noise reduction range (Hiss, Mid, or Full), a HI TRIGGER RANGE switch that extends the trigger range for extremely noisy situations, and a Trigger Level control⁶. The Smart Gate Pro pedal adds per-channel controls: Trigger Level knobs for gate threshold adjustments on each channel, Gate LEDs that show the level of noise reduction for each channel, and a Sync control that links channels A and B⁵.

Bypass

The rack unit has true hardwire bypass on each channel, so with a channel switched out the signal passes through without the gating circuit in the path¹. The Smart Gate Pro pedal shares this arrangement, with true hardwire bypass outputs on each channel⁵. The standard Smart Gate pedal (M135) is specified with a hardwire bypass rather than a true bypass³.

How it differs from the Smart Gate pedal

The core difference is format and scale. The Smart Gate pedal is a compact stompbox that can be powered by a 9-volt battery, a Dunlop ECB003 9-volt adapter, or Dunlop's DC Brick, Iso-Brick and Mini Iso-Brick power supplies³. The rack unit is a rack piece, and MXR positions it as the big brother to the pedal¹. It also has a dedicated companion: the Smart Gate Pro Foot Controller, which Dunlop describes as the companion pedal to the M235 Smart Gate Pro Rack Module, giving you remote switching from the floor².

For players weighing the two, the press has generally treated the pedal as the entry point. Guitar World's noise gate buying guide calls the Smart Gate simple to use and reasonably priced, which makes it a great option for beginner players, noting it is effectively a single control⁸. The rack unit, at $525.99 as listed in October 2026², sits at the other end of the line from the pedal's $159.99 list price⁹ and the $149 price Guitar Pedal X cited in May 2025²¹⁰⁹.

Power and price

The rack unit runs on 9 volts, powered by the included Dunlop ECB003 adapter, so no separate supply purchase is needed¹. That contrasts with the Smart Gate Pro pedal, whose manual states that an AC adapter must be used to operate it, powered by the Dunlop ECB-004 adapter, an 18-volt DC regulated supply with positive on the barrel and negative on the center⁵.

The M235 Smart Gate Pro Rack Module is listed at $525.99 USD². The companion foot controller is powered by a 9-volt battery, a Dunlop ECB003 9-volt adapter, or the DC Brick, Iso-Brick and Mini Iso-Brick supplies, none of which are included with it².

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