Spring.

Spring models the reverb tanks built into guitar amplifiers, then lets you change physical settings a real tank does not normally offer. Choose a small or large tank, morph from one spring to three and set low and high damping independently. A tube-amp-style tremolo runs before or after the reverb, while the Ribbon and Hotswitch move between sounds as you play. It suits surf guitar as well as synths, drums and vocals, and needs Eventide and iLok accounts but no physical dongle.