If your experiences with filter stompboxes extend only as far as the ones that go wacka-wacka, perhaps you should let Blurst introduce you to sheeeeeeeoooooo, cronk-uh cronk-uh, and whoosh-blurb-blurb-blubble.

Electro-Harmonix’s Blurst is an endlessly entertaining analog filter pedal packed with tone-shaping and modulation options. The filters that appear in wah pedals (your basic wacka-wacka sound) are band-pass, which means they emphasize a slice of frequencies while trimming frequencies above and below the slice. But Blurst employs a low-pass filter, which removes frequencies only above the cutoff point. It’s the quintessential analog-synth filter sound, capable of everything from slow, yawning sweeps to wet-sounding burbles and farts.

With foot-controlled sweeps, you can sculpt the sound of individual notes and chords. It’s the sort of expression you get from a wah pedal, but with a larger collection of fresher-sounding tones.

Blurst of Energy
Burst is solidly built into a standard BB-sized enclosure. The controls include five large knobs, three 3-way toggles, and two footswitches. It requires a 9V power supply (included). Two knobs control the essential low-pass-filter parameters: cutoff frequency and filter resonance (the degree of intensity at the cutoff frequency). But it’s the remaining controls that make Blurst so versatile and fun.

Knobs labeled volume and blend may not sound terribly exciting, but they do important work here. At high resonance settings, Blurst can generate blisteringly loud screeches, moans, and rumbles. The cut-only volume control lets you dial in extreme effects without committing crimes against humanity. Meanwhile, the blend control sets the balance between the dry and filtered sound. (As opposed to a wah sound, which is 100 percent filter.) That way, you can use sounds that might otherwise be too anarchic and over-the-top by mixing them with non-filtered signal.

And then there’s the mighty modulation section.

Ratings

Pros:
Many fine filter tones. Real-time control options. Sturdy build. Good price. Endless fun.

Cons:
Expression pedal not included, but you’ll want one for maximum gratification.

Tones:

Ease of Use:

Build/Design:

Value:

Street:
$134

Electro-Harmonix Blurst Modulated Filter
ehx.com

Wiggle Room
Blurst offers two ways to wiggle: via the onboard LFO oscillator or by connecting any standard controller pedal (not included) and applying modulation in real time. In LFO mode, you can set the modulation speed using the rate knob or via a dedicated tap tempo footswitch. If you’re not comfortable tapping in dotted notes or triplets, the tap divide toggle lets you generate those rhythms from straight quarter-note taps.

Another toggle selects from three modulating waveforms: triangle (a smooth up-and-down motion), a falling sawtooth (BOO-ah, BOO-ah), and a rising sawtooth (ah-BOO, ah-BOO). Between the three waveforms, the filter’s range and feedback settings, and the wet/dry blend, Blurst can summon a vast range of LFO-animated tones. And with Blurst downstream from a fuzz pedal, you get unconventional distortion tones full of freaky resonant peaks.

Blurst Till You Burst
If Blurst’s repertoire ended there, the pedal would merit a positive review. But connecting a controller pedal takes things to another level. LFO-generated modulation is repetitive and regular by nature, but with foot-controlled sweeps, you can sculpt the sound of individual notes and chords. It’s the sort of expression you get from a wah pedal, but with a larger collection of fresher-sounding tones.

A toggle switch lets you assign the expression pedal to either modulation rate or filter cutoff frequency. The former setting is great for complex, ever-shifting sweeps and warbles. The latter produces all manner of cool wah variations. Filter control has two modes: You can set the cutoff frequency solely by pedal, wah-style, or use the rate knob to set a specific cutoff point in the pedal’s heel-down position. You might, for example, enter a precise rhythm for a song using the tap tempo button, veer into faster/crazier modulation using the pedal, and then return with precision to the original, heel-down filter speed.

The Verdict
My day with Blurst was wicked fun, especially after connecting a controller pedal. It was easy to find compelling sounds. Actually, it was hard not to—I recorded all the excerpts in the demo clip within 10 minutes of plugging in for the first time. From clangorous ring-mod dissonance to slow introspective sweeps to watery burbles, Blurst offered up one cool tone after another. The pedal’s build is solid and its price is right. Using Blurst is a productive and cost-effective way to enlarge your palette of filtered tones (though you’ll probably want to add an expression pedal for maximum effect).

Watch the Review Demo: