Twin Dynamic Envelope Filter
The Electro-Harmonix homepage about the BassBalls:
Back by popular demand! One of the most sought-after units in the Electro-Harmonix line, Bassballs is available again! Bassballs’ twin dynamic filters track picking dynamics at slightly different frequencies, creating shifting peaks and notches that simulate human speech! Distortion mode further emphasizes vowel-like overtones and dynamic responsiveness, making Bassballs the ideal accessory for Bass or Guitar.