Electro-Harmonix MICRO Q-TRON Envelope Filter PedalIf you're a player with an affinity for classic auto wah sounds, but you prefer streamlined controls, you'll dig the Electro Harmonix Micro Q Tron. This stompbox is powered by an internal envelope follower, which analyzes the dynamics of your playing to determine the intensity of the wah effect. When you pick harder, you'll get a wider frequency sweep; when you pick more softly, you'll produce a subtler sound. And It's a breeze to dial in a few twists