38. Ground-Plane CBT Loudspeakers: Constant Beamwidth Transducer (CBT) Loudspeaker Circular-Arc Line Arrays

AES Convention: 119 Paper Number:6594
Publication Date: 2005-10-06

This paper describes a design variation of the Ground-Plane CBT Loudspeakers line array that is intended to operate very close to a planar reflecting surface. The original free-standing CBT array is halved lengthwise and then positioned close to a flat surface so that acoustic reflections essentially recreate the missing half of the array. This halved array can then be doubled in size which forms an array which is double the height of the original array. When compared to the original free-standing array, the ground-plane CBT array provides several advantages including: 1. elimination of detrimental floor reflections, 2. doubles array height, 3. doubles array sensitivity, 4. doubles array maximum SPL capability, 5. extends vertical beamwidth control down an octave, and 6. minimizes near-far variation of SPL. This paper explores these characteristics through sound-field simulations and over-the-ground-plane measurements of three systems: 1. a conventional two-way compact monitor, 2. an experimental un-shaded straight-line array, and 3. an experimental CBT Legendre-shaded circular-arc curved-line array.

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Button, Douglas J.; Keele, Jr., D.B. (Don); 2005; Ground-Plane Constant Beamwidth Transducer (CBT) Loudspeaker Circular-Arc Line Arrays [PDF]; Harman International Industries; JBL Professional; Paper 6594; Available from: https://aes2.org/publications/elibrary-page/?id=13350