A.T.V. - Advanced Training Visualizer - Trumpet/CornetATV shank sold separately (works with any backbore with Warburton Threads) Scroll down for instructions! Visualizers have been used successfully as a diagnostic tool by brass teachers since the 1920's. Our approach with the A. T. V. goes far beyond visual diagnostics, providing an advanced, high intensity Isotonic workout and low intensity exercises to develop a relaxed aperture for greatly improved tone in the lower and middle registers. The