Abstract: Conventional analog loudspeakers have a limited dynamic range as compared to the available dynamic range of digital recordings. Digital recordings use up to 24 bits and this implies a dynamic range of 141 dB. Digital loudspeakers, involving 2N single bit devices (with N=24, this number is 1.7×107) have been proposed. The present improvement is the provision of at least one loudspeaker, a plurality of analog drivers and the audio input supplied to a control processor which in turn drives one or more of the plurality of independent analog drivers. The number of drivers in operation at any one time is determined by the amplitude of the input audio signal to the control processor.

Abstract: Conventional analogue loudspeakers have a limited dynamic range as compared to the available dynamic range of digital recordings. Digital recordings use up to 24 bits and this implies a dynamic range of 141 dB. Digital loudspeakers, involving 2?N single bit device (with N=24, this number is 1.7×107) have been proposed. Complexity and poor performance associated with the interaction effects between the different devices have discouraged widespread use of such systems, along with the inability, of most loudspeakers to reproduce realistic absolute levels of sound (up to say 120 dB at 1 m without distortion), so such digital loudspeakers cannot take full advantage of the 24-bit fidelity. This invention provides a loudspeaker with improved dynamic range over prior art systems.

Abstract: A panel-form loudspeaker has a resonant multi-mode radiator panel which is excited at frequencies above the fundamental frequency and the coincidence frequency of the panel to provide high radiation efficiency through multi-modal motions within the panel, in contrast to the pistonic motions required of conventional loudspeakers. The radiator panel is skinned composite with a honeycomb or similar core and must be such that it has a ratio of bending stiffness to the third power of panel mass per unit area (in mks units) of at least 10 and preferably at least 100. An aluminum skinned, aluminum honeycomb cored composite can meet this more severe criterion easily.

Abstract: To overcome acoustic distortion caused by local resonance in panel core cells, a resonant multi-mode radiator element is provided for a panel form loudspeaker with a functional upper frequency limit ƒmax. The element has skins and a cellular based core, the skins have a thickness h, a Young's modulus &Egr; a Poisson's ratio of &ngr; and a material density &rgr; and the core has a cell size lcell characterized in that the cell size lcell is less than equation (2).