Electro-Harmonix Blurst Modulated FilterMaker: Electro Harmonix Model: Blurst Modulated Filter Condition: New Description: EHX has grafted technology found in keyboard and modular synthesizers into a pedal designed for guitarists and bass players. The Blurst modulates an instruments sound like an envelope filter, but instead of the filters response being controlled by playing dynamics, its controlled by an internal oscillator. The Blurst is a must have for the adventurous player who wants