In this photograph David Tudor and Fred Waldhauer set up Tudor’s piece Bandoneon !  on the performance platform. Ten different types of microphones were attached to the  bandoneon and picked up the sound which was distributed to four different processing  devices. The first was a forty-channel filter circuit. Twelve of its output channels were  fed to the 12 speakers; the remaining channels activated relays to turn on and off  spotlights on the balcony. Second, a processing circuit, which Tudor had built himself,  fed four transducers attached to wood and metal structures moving on the Armory floor.  The third was the 20-channel proportional control system, built by Fred Waldhauer,  which controlled the intensity of eight lights mounted on the performance platform and  fed the sound into different speakers around the Armory. The fourth device used the  sound to modify images on the three television projectors.