recording industry in the 1920s and 1930s, studio monitors were used primarily to check for noise interference and obvious technical problems rather than for making artistic evaluations of the performance and recording. Musicians were recorded live and the producer judged the performance on this basis, relying on simple tried-and-true microphone techniques to ensure that it had been adequately captured; playback through monitors was used simply to check that no obvious technical flaws had spoiled the original recording. As a result, early monitors tended to be basic loudspeaker cabinets. The state-of-the-art loudspeakers of the era were massive horn-loaded systems which were mostly used in cinemas. High-end loudspeaker design grew out of the demands of the motion picture industry and most of the early loudspeaker pioneers worked in Los Angeles where they attempted to solve the problems of cinema sound. Stereophonic sound was in its infancy, having been pioneered in Britain by an engineer who worked for EMI. Designing monitors for recording studios was not a major priority. 1940s and 1950s The first high-quality loudspeaker developed expressly as a studio monitor was the Altec Lansing Duplex 604 in 1944. This innovative driver has historically been regarded as growing out of the work of James Bullough Lansing who had previously supplied the drivers for the Shearer Horn in 1936, a speaker that had rapidly become the industry standard in motion-picture sound. He had also designed the smaller Iconic and this was widely employed at the time as a motion-picture studio monitor. The 604 was a relatively compact coaxial design and within a few years it became the industry standard in the United States, a position it maintained in its various incarnations (the 604 went through eleven model-changes) over the next 25 years. It was common in US studios throughout the 1950s and 60s and remained in continuous production until 1998. In the UK, Tannoy introduced its own coaxial design, the Dual Concentric, and this assumed the same reference role in Europe as the Altec 604 held in the US. The British Broadcasting Corporation researchers conducted evaluations on as many speakers as they could obtain in around 1948, but found commercial loudspeaker makers had little to offer that met their requirements. The BBC needed speakers that worked well with program material within real professional and domestic settings environments, and not just fulfil technical measurements such as frequency-response, distortion, monitors in anechoic chambers. Above all,