Check the listing for details. Electro-Harmonix Micro Q-Tron Envelope Filter Pedal. Condition: New. Listed at 112.50 USD. Electro Harmonix Micro Q-Tron The EHX Micro Q-Tron is a smooth envelope filter with a funky wah-wah tone. The filter is controlled by its internal envelope follower, analyzing the volume of your notes and the dynamics of your playing to directly sweep the filter’s center or cutoff frequency. A stronger attack or louder note will produce a wider frequency sweep while softer playing produces more subtle effects. Use the Q control to make the effect more dramatic. Features True bypassDrive control sets sensitivity and filter sweep rangeSelectable low pass, band pass or high pass filtersQ control sets the filter’s bandwidth from smooth to funkyTough and compact die-cast chassis9V battery included Specs Circuit: AnalogBypass: True BypassAudio: MonoPower Supply: 9V battery included (optional 9.6VDC-200mA power adapter not included)Dimensions (in): 4.75 x 4 x 2.25Current Draw: 15mAYear Released: 2006