The DOD FX25B Envelope Filter is a classic, analog auto-wah pedal produced from roughly 1998 to 2007. It is highly celebrated for delivering dynamic, vocal-like 1970s funk sweeps without requiring a manual foot treadle.

Though originally designed with bass players in mind, its flexible controls make it widely popular for electric guitar, synthesizers, and reggae dub tracks.

Key Controls and Functions
Unlike its predecessor (the FX25), the "B" version introduced a critical update to help musicians retain their core instrument frequencies:

• Blend: Mixes the dry unaltered signal with the wet filtered effect. Turning it counter-clockwise keeps the low-end bass from thinning out.
• Sensitivity: Determines how hard you must strike the strings to trigger the envelope sweep. Turn it up for soft fingerstyle playing and down for aggressive slapping.
• Range: Adjusts the frequency depth and direction of the filter sweep. Turning it clockwise targets the brighter high end.
• Condition: Overall Excellent showing light user wear, it has been tested and is fully functional

Notable Users
The pedal's distinct "quacky" tone has been utilized by several legendary bassists and guitarists:

• Bootsy Collins (Parliament-Funkadelic)
• Flea (Red Hot Chili Peppers—notably using it in 90s instructional videos)
• Wes Borland (Limp Bizkit)
• Doug Wimbish (Living Colour)