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WHITE PAPER COAXIAL RIBBON LINESOURCE
THE NEXT STEP TOWARD PERFECT AUDIO REPRODUCTION
Music reproduction whether in the home or in large public venues is plagued by the acoustic effects of the physical space (room)in which it takes place. Reflections and standing waves distort the accuracy of the sound at the listening position from that initially produced by the loudspeakers.Control and minimization of room effects is one of the critical frontiers of music reproduction. Delivering the soundwave faithfully to the listener's ears in a typical listening environment is the objective of this development.
The ideal loudspeaker would deliver consistent, accurate, high quality sound to any point in the listening space. Newform's Coaxial Ribbon LineSource delivers consistent, high quality sound to a larger portion of the listening space than has been possible before.
This approach is inherently free from the flaws of conventional dome based point source loudspeakers and incorporates features which allow an ideal (ideal = the best practically achievable, but almost certainly not perfect) installation to be quickly achieved in many different rooms for many different listeners.
The traditional loudspeaker consists of a larger cone diaphragm bass transducer possibly a cone or dome midrange and a cone or dome high frequency tweeter. This configuration has a number of significant acoustic drawbacks in its ability to deliver the soundwave that the separate drivers create faithfully through the acoustic space to the listeners ear. The overlapping hemispherical dispersion patterns of these dome/box loudspeakers using single, small round diaphragms of different sizes for different frequencies staggered on a flat baffle assures cancellation patterns in many directions from the baffle. It also assures that large numbers of room resonances are excited and that reflected sound arrives at the listeners ear from many different sources at different times to degrade the integrity of the original wave created at the diaphragms.
A line source loudspeaker is one with multiple identical drivers arranged vertically in a line or one vertical long driver. The resultant long, narrow diaphragm creates a pattern of dispersion radically different from that of a round diaphragm. Instead of being hemispheric, the dispersion pattern of a line source radiator is resembles a column or cylinder. Round and broad but with limited and well defined height.
A long narrow driver such as a Ribbon or thin electrostatic transducer also produces a pattern of dispersion that effectively extends the "near field" response, ie the response of the loudspeaker before it is affected by interaction with the room, further into the listening area. The distance the near field effect is projected depends on the length of the effective diaphragm and the frequency it is producing.
Line source loudspeakers (classic electrostatic and Ribbon speakers) have much more controlled vertical dispersion and therefore excite fewer detrimental room interactions but as previously implemented have introduced several other deficiencies of their own. These deficiencies stem from the alignment on the same plane of the drivers in 2 or more vertical lines beside each other. By placing radiating surfaces beside each other, the waves created by them will arrive at different horizontal points in the room at slightly different times causing many amplitude and phase anomalies which degrade the perceived accuracy of the music.
Only in one very narrow area are these anomalies minimized giving rise to the term "head-in-a-vice sweet spot". Slight movement of the listening head produces distinctly different acoustical performance. This also precludes more than one listener from enjoying ideal response.
The traditional parallel line source configuration gives rise to the same kind of interference in the horizontal plane that is inherent with conventional dome/cone speakers in the vertical plane.
Besides phase differentials, other anomalies include baffle bounce and diffraction. Baffle bounce occurs when a wave from a driver (typically high frequency) radiates to the side of the driver and "bounces" off of the baffle or the diaphragms of other adjacent drivers. Diffraction occurs when the sound wave encounters a radical change in the baffle surface along which it is radiating - either a corner of a loudspeaker enclosure or the edge of a panel speaker.
For conventional or parallel line source loudspeakers, phase coherence due to the physical offset of the drivers cannot be corrected over a large listening area by electrical means. A coaxial line source holds much higher potential for delivering phase and frequency response accuracy in a large area in any listening space.
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