Plasma Tweeter

The plasma tweeter is perhaps one of the more exotic audio reproduction devices. In theory, it is essentially perfect - a practically massless arc that can respond instantaneously to its inputs. Nevertheless, in practice, plasma tweeters often don't perform as well as they should due to various difficulties. For the 2008 ISEF competition, a pair of plasma tweeters are being constructed that are more powerful than conventional plasma tweeters, have a higher sound quality, and couple to a type of omnidirectional waveguide for safety purposes, as well as for lowered distortion. While this project is still in the works, a preliminary schematic is available. The schematic shows the oscillator section of the plasma tweeter. The first tube, the 807 and 6l6, accepts an input from the modulator. This tube oscillates at approximately 20MHz, and then the signal is coupled to a grounded grid parallel to a 811 RF amplifier. The 811 amplifies this signal greatly, and then a tesla coil steps up the voltage, aided by capacitive feedback. The voltage at this point exceeds air's ionized voltage of 30KV, and plasma is formed.