MXR Bass Envelope Filter

The MXR Bass Envelope Filter is an analog envelope filter pedal made by MXR and designed specifically for bass. An envelope filter listens to how hard you pluck and opens a resonant filter in response, giving the quacky, vocal funk sounds associated with the effect. MXR describes it as delivering "classic analog envelope filter sounds" in a compact pedal, with separate Dry and Effect level controls so you can keep your low end intact while the filter does its thing¹.

The pedal was introduced in 2010 as part of MXR's Bass Innovations line², and it carries on a family name: the original MXR Envelope Filter, the MX-120, was made in Rochester, New York in 1979³. The current list price is $179.99⁴; Premier Guitar's review pegged it at $149 street⁵.

The controls: Dry, Effect, Decay, Q and Sensitivity

The pedal has five knobs, and they split into two jobs. Dry and FX set the mix of your clean and filtered signals, while Decay, Q and Sensitivity shape the filter's behavior itself⁸².

The separate Dry and FX controls are the feature that matters most to bass players, because an envelope filter on its own can thin out the bottom of your sound. MXR's pitch is that you "can bring the funk without losing the low end"¹, and the manual lists the separate level controls specifically "for preserving low end"⁶. Guitar World's reviewers called these controls "absolutely key to shaping the sound you're looking for"⁸, and found the pedal easy to live with, with bad sounds hard to dial in⁸.

For Decay, Guitar World's guidance is to wind it anticlockwise for fast, quacky sounds and clockwise for slower, more subtle effects⁸. The manual includes three sample settings to start from⁶:

• Bottom Dweller: synth bass
• Bubble Funk: classic 70's funk
• Gorilla Biscuit: techno/dance

Premier Guitar's reviewer went straight to Bubble Funk, described there as "classic '70s funk"⁵.

Power and connections

Setup is simple: run a cable from your bass into the INPUT jack and another from the OUTPUT jack to your amplifier⁶. Power comes from one of three sources¹:

• A 9-volt battery (remove the bottom plate to install it)⁶
• A Dunlop ECB003 9-volt adapter¹
• The DC Brick, Iso-Brick or Mini Iso-Brick power supplies, sold separately¹

The 2023 Blackout Series manual also lists the Dunlop ECB003/ECB003EU adapter and MXR Brick Series power supplies⁹. The power supply circuitry is designed to withstand over-voltage or polarity mishaps, which protects the pedal if a supply is connected the wrong way¹. At 6 mA of current draw, it is a light load on a shared pedalboard supply⁶.

On bypass, the sources use slightly different wording: the current product page says true-bypass switching preserves your tone in bypass mode¹, while the 2019 manual's specification table reads "True Hardwire"⁶. Either way, the signal passes through unaffected with the effect off.

Filter sweep: 76 Hz to 3.2 kHz

The filter's center frequency sweeps from 76 Hz to 3.2 kHz⁶, a range that reaches down into bass territory rather than sitting entirely in the guitar-focused upper mids. For comparison, the Beigel Sound Lab Envelope Controlled Filter's HI mode sweeps from 350 Hz to 12 kHz¹⁰, so the MXR's range is weighted toward the low frequencies a bass player actually uses.

The manual's full specification set⁷:

The decay stop frequency range of 76 Hz to 1.3 kHz⁶ means the Decay knob decides where the filter settles after the initial sweep, which is what separates a quick quack from a slow, blooming sweep.

The Blackout Series edition

In 2025 MXR marked 15 years of Bass Innovations with a special edition version of the pedal, the MXR Blackout Series Bass Envelope Filter⁹⁷⁸. It was a run of 1,500 pieces⁹, finished in a matte black housing with gloss black text and a bright yellow LED in place of the standard pedal's blue LED⁹⁶. A companion Blackout Series Bass Compressor was released in the same 1,500-piece format¹¹.

Both versions share the same Phase 90-size aluminum housing, which MXR describes as durable and lightweight, and the same control set, power options and true-bypass switching¹⁹.

What reviewers said

Premier Guitar reviewed the M82 and found it held its own against the competition, with the blend controls as the standout:

The same review noted the sparkle-purple finish, five knobs and true-bypass footswitch, and found the pedal sturdy and a bit smaller than most stompboxes⁵. Bassist Fabrizio Grossi, interviewed by Guitar World, was blunt in its favor:

Guitar World's 2025 guide to the best bass effects pedals lists the M 82 among its 11 picks, citing its funky analog tones, compact size and separate Dry and FX controls⁸.

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