Used Maxon AF9 Envelope Filter Pedal

The AF‑9 is an optical, analog envelope filter voiced after the vintage Mu‑Tron III, giving it a smooth, musical response rather than the harshness of some digital filters. It functions as an auto‑wah that opens and closes with your pick attack, making it easy to dial in percussive, syncopated grooves or more laid‑back, watery textures without riding a treadle.