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Horn Speaker and Method for Producing Low Distortion Sound

US Patent: 4,152,552
Date Filed: January 23, 1978
Date Issued: May 1, 1979
Inventors: John D. Meyer
When he first started working in concert sound reinforcement in the late 1960s, John Meyer realized that only horn-based systems could offer both the high efficiency and precise directional control required for large-scale sound reinforcement systems. However, horn-loaded systems inevitably introduced far more distortion than direct radiating systems operating at the same levels.

A primary cause of distortion in conventional drivers comes from their typically having low-compliance suspensions and a diaphragm excursion substantially of a linear constant displacement. While the low-compliance suspension can help flatten frequency response, it interacts with the inherently non-linear characteristics of air in the driver throat to generate distortion.

Meyer began to work intensively on this problem while working at the Institute for Advanced Musical Studies in Switzerland in the 1970s, setting a goal of bringing the distortion in horn-based systems down within the same range as direct radiators. As described in this first, foundational patent, Meyer succeeded in developing a new, integrated approach to horn-based loudspeakers that reduced distortion by a factor of ten when compared to comparable horn/driver combinations of that era.

The patent reflects Meyer's underlying commitment — continuing to this day — to solving problems through an integrated systems approach. Prior to this patent, most drivers and horns were designed separately and then mated together after the fact. The drivers were designed to achieve linear response within a specified pass band, while the horns were designed separately to achieve specified directional characteristics. When the two were put together (often coupled by acoustically problematic adapters), the combination usually produced substantial increases in overall distortion.

In contrast, Meyer's patent describes an integrated system wherein the characteristics of the horn are specifically designed to limit nonlinearities. In Meyer's patented system, the horn-driver combination compensates for these characteristics, thereby greatly reducing distortion. This technology led to construction of the first horn-based systems suitable for highly demanding applications such as opera and classical concerts.