Envelope Filter

The FX25 Envelope Filter was derived from DOD's well-received 440 Envelope Filter. Like the 440, the FX25 uses a bandpass filter circuit where the peak frequency is determined by the input signal level, for a touch-controlled wah or auto-wah effect. The FX25 was one of the original ten DOD FX-series pedals that debuted in 1982, and remained in production until it was replaced by the FX25B in 1998.