http://www.vfepedals.com/mini-mu The MINI MU is derived from the classic Mutron III envelope filter (aka autowah), and has all the same great fat and funky filter sweeps inside a much smaller box. A few extras have been added, namely an active clean gain stage and an "in between" position on the range switch. With the included charge pump, the MINI MU runs on +/-9V like the original without needing a special power supply or two batteries.