Abstract: A microphone has first and second differentially interconnected capsules angularly and linearly displaced from each other by a predetermined amount.

Abstract: A loudspeaker and enclosure assembly, comprising: a load bearing member exhibiting good thermal conductivity; at least one loudspeaker mounted on the load bearing member and in thermal engagement therewith; and, an enclosure having walls formed of rigid light-weight material mounted on the load bearing member to enclose the at least one loudspeaker, whereby the assembly is easily moved and mounted and thermal energy generated by operation of the loudspeaker is effectively dissipated through the load bearing member. The enclosure may be a rigid foam-filled member defining a generally funnel-shaped bore therein to form a horn for the loudspeaker, whereby a modular construction of interchangeable integrally formed enclosures and horns can be achieved.

Abstract: A loudspeaker horn has a throat section with a rectangular cross section to which the driver unit is coupled. The throat section has substantially parallel side walls joined together by diverging top and bottom walls. The horn has a rectangular mouth which is formed by a bell section which runs between the throat section and the mouth with an angular divergence corresponding to the desired horn dispersion pattern. If the mouth is made square, equal horizontal and vertical low frequency directivity roll off can be provided. On the other hand, with the speaker of the present invention, various relative horizontal and vertical directivity control can be obtained with different aspect ratios for the mouth. The walls of the bell section may be additionally flared outwardly at a portion thereof near the mouth to provide improved midrange directivity control. The use of planar sides between the throat section and the mouth also makes for an improved directivity pattern.

Abstract: A method and apparatus for determining the directivity index (DI) and directivity factor (Q) of a loudspeaker is described. A microphone is placed in the throat of a horn-type loudspeaker to measure the acoustical pressure at this point. A second microphone is placed along an extension of a central axis of a loudspeaker at a predetermined distance from the mouth of the loudspeaker to measure the acoustical pressure at this point. The output of each of the microphones is rectified and converted to decibel form. The decibel signal representing acoustical pressure at the throat is subtracted from the signal representing the measured pressure at the predetermined distance. A signal (in decibel form) representing the distance of the second microphone from the mouth of the horn is added to the difference signal and a signal (in decibel form) in accordance with the diameter of the loudspeaker throat is subtracted from the difference signal to provide a signal in accordance with directivity index.

Abstract: An acoustical transformer or "phasing plug" for coupling sound from a speaker diaphragm to the throat of a horn. The phasing plug of the invention is in the general shape of a dome on one side and a truncated cone on the other, and has evenly spaced radial slots or channels formed therein, these slots forming air passageways for propagation of the soundwaves. The walls of the slots are tapered exponentially from their inlet ends at the speaker diaphragm towards a flat plane outlet at the throat of the horn, to provide an optimum impedance match between the output of the diaphragm and the input of the horn; the sound channels formed by the slots exponentially increasing in area between their inlets and outlets. Transformation from a spherical wave front at the input to a plane wave front at the outlet is assured by the shaping of the channels to make the distances between corresponding points at the channel inlets and outlets equal to each other.

Abstract: The coil form for a loudspeaker voice coil is made of a material having high thermal conductivity. The coil form is attached to or integrally formed with a highly thermally conductive spider member which resiliently supports the coil form on the frame structure of the speaker, which also has high thermal conductivity. In one embodiment of the invention a heat sink member to facilitate the dissipation of the thermal energy is attached to the speaker frame structure. In an embodiment involving a horn type speaker, the horn element, which is made of a thermally conductive material, is attached to the speaker frame and also functions as a heat dissipator. In this manner, the likelihood of overheating of the speaker voice coil is greatly diminished.