Abstract: A stage monitoring system is described and claimed that provides musical performers the ability to carefully control the local sounds they are hearing during a performance independently of the house sound system and independently of the other musicians on stage. A complete and unique system constituting an improved method of monitoring oneself during an aural performance, by way of a discreet mixer that sums the collective audio signals coming from a vocal microphone, a mono or stereo instrument input, stereo ambient microphones and signals from two auxiliary inputs. The unit sends the audio signal from the ‘Instrument In’ and the ‘Vocal In’ to an audio recording console or live performance mixing console.

Abstract: A heat exchanger comprises a first tube having a first fin of a first predetermined height extending outward therefrom. A second tube is vertically spaced above the first tube. The second tube has a second fin of a second predetermined height extending outward therefrom. A fan is positioned to force ambient air across the second tube and then across the first tube to heat a fluid flowing therethrough. A method of heating a fluid comprises sequentially flowing the fluid upward through a plurality of vertically spaced rows of substantially horizontal tubes, and forcing air downward over the plurality of tubes to heat the fluid.

Abstract: An apparatus for vaporizing a cryogenic fluid comprises a heat transfer fluid closed circulation loop at least partially defined by an ambient air heat exchanger, a heater, and a vaporizer. The heat exchanger is configured to direct air downward across a plurality of heat exchanger tubes. A cryogenic fluid flows through the vaporizer. The plurality of tubes comprise a first tube having a first fin of a height, h1, and a second tube spaced adjacent the first tube, where the second tube has a second fin of a height, h2, wherein h2 is different from h1.