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  • Electro Harmonix Blurst Modulated Filter Pedal

    By Phil O'Keefe |

    LFO modulated filtering isn't just for keyboard synths anymore


    It was the best of times, it was the Blurst of times… Okay, with apologies to Charles Dickens, I had to get that out of the way right off the bat. With a moniker like Blurst, EHX has got to figure that people are going to have a bit of fun with this pedal's name - but what about the pedal itself? Is it equally fun? And what exactly is the Blurst? I'm glad you asked…




    What You Need To Know

    • The Electro Harmonix Blurst is a modulated analog low-pass filter with adjustable resonance in a compact guitar pedal format that measures 2.75" W x 4.5" L x 2.1" H. Filters are not uncommon in modern musical electronics; wah pedals and envelope filters are types of filter pedals too, but filters of the sort that you'll find in the Blurst are generally far more familiar to keyboardists than guitarists.


    • While an envelope filter uses your playing dynamics to control the filter, the Blurst has an internal multi-waveform low frequency oscillator for that purpose.


    • The Blurst has some pretty wild graphics, with kind of a 50s Sci-Fi meets 60s psychedelia meets Ed Roth / Rat Fink vibe to it. It's certainly colorful, and the players I've asked all seem to like it. The pedal itself is white, as are the labels for all the controls - which are easily readable against the brightly-colored front panel.


    • Likewise, the black position markers on the big white knobs are easy to see in all but the darkest of rooms. There are a total of five - let's take a look at what each one does.


    • Volume sets the overall output level for the pedal when the effect is active. It's possible to get the Blurst to self-oscillate with volume settings past about 2 o'clock when the Blend is turned up all the way along with high Resonance settings; it can be a bit tricky to control, but from there it's possible to use it as a noisemaker by manipulating the Resonance, Range, Rate and Volume controls.


    • Blend allows you to control the ratio of dry guitar (fully counterclockwise) to filter processed signal, which is full-bore when this knob is turned up fully. Blending in some of the unprocessed signal is the key to getting phaser and trem-like sounds from the Blurst.


    • Resonance sets the amount of resonance in the filter, or the filter's Q. Turning this knob up makes the sound more sharply resonant, and simultaneously gives it more volume too.  


    • Rate controls the speed of the internal low frequency oscillator, and how fast it cycles.


    • The center-detented Range knob sets the frequency range of the filter modulation. The maximum range is when this knob is set at noon; turning it lower results in less range and more low frequency emphasis, while turning it up past 12 o'clock also results in less range, but with more emphasis on the higher frequencies.


    • There are three small three-position toggle switches on the top panel too. The one on the far-right is labeled Shape selects the waveform for the Blurst's LFO, with ramp-down sawtooth, triangle and ramp-up sawtooth waveform options. We'll take a look at what the other two toggle switches do in a moment.


    • A Tap (Tempo) footswitch on the lower left hand side of the pedal lets you set the LFO tempo with just a few taps of your foot, and you can do this at any time - even when the pedal is bypassed. A yellow LED just above the Tap footswitch indicates the current LFO rate.


    • The middle of the three top panel toggle switches is a Tap Divide switch and works along with the Tap footswitch; it allows you to select quarter note, dotted eighth note and eighth note triplet values, giving you not only the ability to lock the filter sweep timing to the tempo of your music, but to use alternative rhythmic values.


    • The Bypass footswitch is on the lower right hand side of the pedal. A corresponding orange LED illuminates when the pedal is active. The Blurst features true bypass switching.
    • Power is handled by an external 9.6V DC 200mA power adapter, which is included with the pedal. Battery powering is not an option. The Blurst draws 56mA at 9V DC. The 2.1mm center-negative power jack is mounted on the end of the pedal just above the knobs.



    • The Blurst's input and output jacks are mounted on the right and left sides of the pedal, respectively. Input impedance is 2.2 Mohm, and the output impedance is 220 ohm.  




    • Also on the left side of the pedal is an EXP Jack for connecting an optional external expression pedal to the Blurst. This can be switched to control the filter's cutoff frequency, or the Rate or Range using the last of the three top-panel toggle switches to dial up whichever of the three you want to control with the pedal. When used with Rate or Range, the knobs themselves set the maximum value while the pedal allows you to adjust things within that range, so it's possible to set limits, or to set the knobs wide open and allow the expression pedal to control the parameter's entire range.


    • You can also use the EXP jack to supply a control voltage to the Blurst from other devices, such as the Electro Harmonix 8-Step Program, your Eurorack rig or hardware synth - you get the idea.         




    • Unfortunately, low-pass filtering is all that is available. It would have been nice to have bandpass and high-pass filter options too.



    This pedal is Blursting with cool synth-style modulated filter sounds. It's a must-have for noise-rock, funk, EDM and electronica, and experimental guitarists and bassists in general, regardless of genre, will find loads to love about it. It's also capable of more subtle sounds too, so even if your tastes run less avant-garde, don't let that scare you off. While Electro Harmonix is marketing the Blurst to "adventurous guitarists and bassists", and I don't want to Blurst their bubble, but they're not the only ones who might enjoy it. In addition to coaxing more subtle sounds out of it with guitar and bass that were reminiscent of phaser, wah and tremolo, I found it to be a great companion for the EHX drum synths - the Super Space Drum and Crash Pad. It's also a great pedal to use alongside guitar synth-oriented pedals, such as the Electro Harmonix Superego. You may find it useful on other things too, so don't be afraid to experiment! Once again, Electro Harmonix keeps the cost reasonable while giving musicians the kind of cool tools that invite experimentation and that help them to develop their own sound.  It's the best of times indeed! -HC-


    Have questions or comments about this review? Want to tell us how you're using your Blurst? Then make sure you click here to join the discussion in the HC Effects forum.



    Electro Harmonix Blurst modulated filter pedal ($183.20 MSRP, $137.40 "street")

    Electro Harmonix Blurst product web page    


    You can purchase the EHX Blurst from:


    Guitar Center    

    Musician's Friend    













    Phil O'Keefe is a multi-instrumentalist, recording engineer / producer and the Senior Editor of Harmony Central. He has engineered, produced and performed on countless recording sessions in a diverse range of styles, with artists such as Alien Ant Farm, Jules Day, Voodoo Glow Skulls, John McGill, Michael Knott and Alexa's Wish. He is a former featured monthly columnist for EQ magazine, and his articles and product reviews have also appeared in Keyboard, Electronic Musician and Guitar Player magazines.  


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