The Flow Vintage Tremolo is a technically advanced guitar effects pedal, offering three distinct tube-driven tremolo effects, tap tempo, an accurately emulated preamp circuit, volume boost, and true/buffered bypass, all packed into a compact stompbox. Evolved from the Astra Modulation Machine, it provides three tremolo flavors, ranging from vintage harmonic throb to modern square waveforms. The Dharma mode replicates early '60s American amp tremolo with added volume modulation and phase shifting. The 65 mode precisely emulates a classic 1965 American tube amp's optical tremolo circuit, while the Square mode delivers modern rhythmic tremolo effects using virtual optical photocell technology. Furthermore, it includes a warm tube preamp sound and durability for years of reliable performance, making it a versatile tool for achieving a wide range of tremolo effects in a compact and convenient format.Universal Audio GPS-FLOW Features:Authentic emulations of three tube-driven tremolo effects, captured in a compact stompboxPerfectly captured tube preamp for fat, three-dimensional tremolo tonesThree tremolo modes: Dharma (harmonic tremolo), 65 (round, sine wave), and Square (choppier, square wave)Onboard tap tempo for syncing trem effectsVolume control and true/buffered bypassTimeless UA design and craftsmanship, built for decades of dependable performanceUniversal Audio GPS-FLOW Specifications:Power requirements: Isolated 9VDC, center-negative, 250mA minimum (sold separately)Inputs: 1 x 1/4” TS unbalancedOutputs: 1 x 1/4” TS unbalancedUSB Type-C for updates via computerHeight: 5.81 cm, 2.29 inchesWidth: 6.55 cm, 2.58 inchesDepth: 12.07 cm, 4.75 inchesWeight: 0.659 lbs (0.299 kg) Universal Audio Flow Vintage Tremolo UAFX Tube-Driven Tremolo Effects Guitar Pedal.