Source Audio SA243 Vertigo Tremolo Effect Pedal Three styles of tremolo including Opto Tremolo, Harmonic Tremolo, and Bias Tremolo. Download additional hybrid modulation effect algorithms or access a deep editing system with the Neuro Mobile App for iOS and Android. Pair the Vertigo with the Neuro Hub and save up to 128 presets recallable with MIDI program change messages from an external MIDI foot controller.