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

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: (1) a vented cabinet having a volume of 28 liters (1 cubic foot); (2) 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; and (3) 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 + or - 3 dB from 56 Hz to 15kHz and the maximum sound level is 100 dB(A) at 1m on axis measured in a typical listening room using light music.