The AD50VT features the patented VOX Valve Reactor found on all Valvetronix products. The Valve Reactor circuit uses a 12AX7 triode vacuum tube together with an actual low-wattage tube power amp circuit, a virtual output transformer and a dummy speaker circuit that simulates the impedance changes of a real speaker. It also reconfigures itself so that its characteristics are the same as the amps it’s modeling (class A, class AB, negative feedback circuit, etc.). This means that all of the nuances of the original amp model including sound, feel, distortion and presence are reproduced accurately. 50.67cms (19.95") (H) x 57.81cms (22.76") (W) x 26.5cms (10.43") (D)