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MXR M82 Bass Envelope Filter Pedal Review

Funky and flexible bass envelope filter

Download Example 1
Bubble Funk (classic '70s funk)
Clip recorded with a G&L L-2500 bass into pedal, into Axeport Pro and Garage Band
If you’re trying to cop that ’70s funk sound on bass, you need to listen to classic funk bands and develop the right musical vocabulary. But to really nail it, you also need a bass envelope filter pedal.

Essentially, an envelope filter works like a wah pedal that responds to your string attack. The harder you hit the string, the more the filter sweeps upward, producing a quacking effect. It takes some time to learn how to adjust an envelope filter’s various knobs, but it’s way easier to play quick, staccato licks through an envelope filter than to operate a wah pedal.

Enter the MXR M82
The MXR M82 is an analog envelope filter designed to preserve the instrument’s natural character while adding a wah effect to the signal. It boasts a sparkle-purple finish, five knobs, and a true-bypass footswitch. Overall, this pedal feels quite sturdy, and it’s a bit smaller than most stompboxes.

The M82 is powered by a 9-volt battery or an optional power supply. Accessing the battery requires removing the bottom plate, which is less convenient than a pop-out battery box. Removing this plate, I found a bright red circuit board filling most of the box, with just enough room to house the 9-volt cell.

The pedal’s five knobs are grouped into two rows. On the top row, the FX knob controls the level of effect, while the Dry knob sets the level of the unprocessed original signal. This is really important for bass, because as the filter sweeps upward, the note’s bottom end drops away. The Dry knob lets you keep the lows by blending in straight bass tone.

The three knobs on the lower row— Decay, Q, and Sensitivity—shape the effect itself. Decay sets the floor frequency for the wah effect. When a filter sweeps upward on a note’s attack, it then heads back down to where it started. As you turn Decay clockwise, the less downward sweep you hear. Conversely, lower Decay settings cause deeper filter plunges. Below noon, a note sweeps quite low before the filter releases.

The M82’s manual explains that the Q control adjusts the “intensity” of the effect, but the control actually seems to influence the width of the frequency sweep. At lower Q settings, the filter sweeps a narrower band of frequencies. At higher Q settings, the filter covers a wider range.

The final control is Sensitivity. This knob is key to achieving adequate quack. Essentially, Sensitivity influences how easily your note attack sweeps the filter. Raising the sensitivity lets you trigger the wah effect with a lighter attack. But if you play hard or your bass has hot pickups, setting the sensitivity too high can leave all your notes at the high end of the filter’s sweep. High Sensitivity settings also tend to emphasize string noise more than I’d like.

Twirling the Knobs
The M82’s instruction pamphlet offers three sample settings, and I immediately went for “Bubble Funk,” which is described as “classic ’70s funk.” It’s that burpy, quacky sound that makes you want to put on a paisley polyester shirt with a big collar, turn on a strobe light, and have a blast boogying! The best part is that the M82 accomplishes that funk sound in a way that sounds natural instead of overprocessed. I liked the initial sound, but I liked it even more when I brought up the Decay a bit so it didn’t sweep quite so low and backed off the Sensitivity so it didn’t feel too compressed. The other two sample settings—“Bottom Dweller,” which served up mainly the note’s fundamental, and “Gorilla Biscuit,” which seemed a little too thin to hold up a bass line— didn’t quite do it for me, but it I found that subtle tweaking of both yielded usable results with a lot of potential.

Setting the M82’s controls is like most envelope filters I’ve played. It takes careful experimenting to get the sound you’re after, and it’s easy to miss and brew up an unwanted sound. Because envelope filters are touch sensitive and their response varies by the strength of the instrument’s output, adjusting the pedal is not a one-size- fits-all proposition. But that’s the trade-off for analog envelope filters in general. Digital envelope filters typically have an easier setup, but the resulting sound usually isn’t quite as satisfying as with analog units like the M82.

The Verdict
If you’re after a good envelope sound, the M82 proves itself to be a strong contender in the analog filter world. Its separate level controls for dry and wet sounds are an especially important advantage over the competition.
Buy if...
you need a flexible envelope filter pedal that delivers a credible frequency-sweeping sound.
Skip if...
you’re not looking to make your bass quack.

Street $149 - Dunlop Manufacturing -