The Electro-Harmonix Nano Metal Muff is a compact analog distortion pedal with a built-in noise gate, released by Electro-Harmonix in 20211. It is a scaled-down take on the company's Metal Muff with Top Boost, keeping the original's three-band EQ while adding a gate that mutes hum and hiss when you stop playing12. Electro-Harmonix describes it as "weaponized distortion" paired with "an extremely powerful EQ section," built for players who want hard-hitting, aggressive high-gain sounds1.
What it does: high-gain distortion with a built-in noise gate
The Nano Metal Muff sits in the Metal Muff family, which Guitar World's Chris Corfield traced back to the original Metal Muff's formula of "tons of gain, flexible multiband EQ and a top-boost circuit"5. The Nano version shrinks that concept into a chassis about half the size of the original, without removing what Corfield called the original's "penchant for heaviness"6. GuitarPlayer reported at launch that the pedal keeps the original's bass, mid and treble EQ, each able to cut or boost2.
The feature that sets the Nano apart from the earlier Metal Muff is the gate. The GATE knob sets a noise floor threshold: when the signal at the input jack falls below that threshold, the gate mutes the output jack, removing hum and noise between phrases1. The gate has its own LED that lights whenever it is engaged, so you can see when it is actually clamping down1. Premier Guitar's buying guide described the result as "an aggressive, heavy tone with a tight low end," noting the pedal's "+/- 14 dB of bass, a powerful noise gate, and an LED to let you know when the gate is on"7.
For players comparing Muffs, Guitar World's Trevor Curwen counted eight different Muffs available in Nano-sized enclosures, though only three of them carry the Nano prefix3. The family also includes the discontinued Pocket Metal Muff, which was discontinued in 2020 and offered a simpler control set with selectable distortion amount and a master volume8.
The controls
The pedal has six knobs and one footswitch. Here is what each one does, per Electro-Harmonix1:
| Control | What it does |
|---|---|
| VOLUME | Sets the overall output level1 |
| GATE | Adjusts the noise floor threshold; mutes the output when the input signal falls below it. Set fully counter-clockwise to disable the gate1 |
| DISTORTION | Adjusts the amount of distortion and saturation; turn clockwise for more saturation1 |
| TREBLE | Provides up to 10dB of cut and boost in the treble frequency range1 |
| MID | Midrange cut and boost, part of the three-band EQ carried over from the original23 |
| BASS | Bass cut and boost, part of the same EQ section23 |
| BYPASS footswitch | Toggles between effect and buffered bypass; the STATUS LED lights when the pedal is engaged1 |
Guitar World's review lists the same control set: Volume, Gate, Distortion, Treble, Mid, Bass, and the Bypass footswitch3.
A practical point on the gate: because it works by muting the output whenever the input signal drops below the threshold, setting it too aggressively can clip the tail of sustained notes. If you want the pedal's distortion without any gating at all, Electro-Harmonix says to set the GATE knob fully counter-clockwise, which disables it1.
Power, bypass and connections
The Nano Metal Muff runs on the included 9V battery or an optional 9.6VDC-200mA power adapter, which is not included and draws 24 mA1. GuitarPlayer noted it accepts a standard EHX 9.6DC200mA supply4. There is no true bypass here: the pedal uses buffered bypass, and in bypass mode the input is connected to the output through a buffer circuit1. Input impedance is 1MΩ and output impedance is 600Ω1.
What reviewers said
Guitar World's Trevor Curwen reviewed the pedal and called it "a surprisingly versatile distortion pedal that push your amp into throaty drive or split the atom when maxed," finding it pedalboard-friendly and affordable overall3. Premier Guitar's high-gain buying guide highlighted the tight low end and the powerful gate as its distinguishing features7.
"A surprisingly versatile distortion pedal that push your amp into throaty drive or split the atom when maxed, it won't t..."
At launch in January 2021, Guitar World reported the pedal available for $722; the current Electro-Harmonix list price is $84.401, and Guitar World's review gives the UK price as £79217.
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Questions
Does the Nano Metal Muff have a noise gate?
Yes. The pedal has a GATE knob that sets a noise floor threshold, and the gate mutes the output whenever the signal at the input falls below that threshold. An LED on the pedal lights up whenever the gate is engaged, so you can see at a glance when it is working.
Is the Nano Metal Muff true bypass?
No. The Nano Metal Muff uses buffered bypass. When the pedal is off, the input is connected to the output through a buffer circuit, and the output impedance at the output jack is 600 ohms. A single Bypass footswitch toggles between the effect and buffered bypass.
What is the difference between the Metal Muff and the Nano Metal Muff?
The Nano Metal Muff is a smaller version of the Metal Muff, in a chassis about half the size of the original, with the original's bass, mid and treble EQ carried over. The Nano adds a built-in noise gate with its own threshold control and status LED, which the original Metal Muff with Top Boost does not have.
How do you turn off the gate on the Nano Metal Muff?
Set the GATE knob fully counter-clockwise. That disables the gate entirely, so the pedal passes your signal, including any hum or noise, without muting the output. Turning the knob clockwise raises the noise floor threshold and makes the gate more aggressive.
Sources (8)
- Nano Metal Muff, Electro-Harmonix (www.ehx.com)
- Electro-Harmonix supercharges the Metal Muff with new noise gate-equipped Nano design, Guitar World, 2021-01-04
- Electro-Harmonix Nano Metal Muff review, Guitar World, 2023-11-01
- Electro-Harmonix Unveils New Nano Metal Muff Distortion Pedal, GuitarPlayer, 2021-01-04
- Electro-Harmonix Metal Muff, Guitar World, 2007-04-26
- Best cheap distortion pedals: get your perfect rock tone for less money, Guitar World, 2024-01-31
- High-Gain Pedals: Transform Your Tone with Fire, Premier Guitar, 2024-12-24
- Pocket Metal Muff, Electro-Harmonix (ehx.com), 2020
