Keeley Neutrino V2 Envelope Filter PedalThe Keeley Neutrino V2 is an amazingly toneful and compact form of the classic opto coupler envelope filter. The Neutrino takes your guitar playing and creates an automatic wah sound based on your pick attack! Envelope filters or auto wahs as they are often called, sound and react best when they are opto coupler based. The opto couplers used in the Neutrino are particularly smooth, giving you an amazing vowel like tone. The Keeley Neutrino gives you 3