BBC RD 1983/10

RESEARCH DEPARTMENT REPORT

The design of the prototype LS 5/9 studio monitoring loudspeaker

K.E. Randall, M.I.E.E., C.D. Mathers, M.Sc., M.I.E.E., M.I.O.A.

Research Department, Engineering Division THE BRITISH BROADCASTING CORPORATION August 1983

BBC RD 1983/10 UDC 621.395.623.8.001

THE DESIGN OF THE PROTOTYPE LS 5/9 STUDIO MONITORING LOUDSPEAKER

K.E. Randall, M.I.E.E., C.D. Mathers, M.Sc., M.I.E.E., M.I.O.A.

Summary

The prototype of a new medium-power studio monitor is described which is physically small enough to be accommodated in areas where a large high-power monitor would be inappropriate.

The main design and performance features are as follows: - A vented cabinet having a volume of 28 litres (1 cubic foot). Two drive units; a proprietary 34mm soft-domed high frequency unit and a BBC-designed 200mm low-frequency unit having a polypropylene diaphragm and a high temperature voice-coil. A low-level cross-over circuit feeds a 50 watt stereo amplifier which drives the units separately; the cross-over frequency is 2.4 kHz. The axial frequency response is ±3 dB from 56 Hz to 16 kHz and the maximum sound level is 100 dB(A) at 1m on axis measured in a typical listening room using light music.

Issued under the authority of

Research Department, Engineering Division, BRITISH BROADCASTING CORPORATION Head of Research Department August 1983 (PH-245)

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