Tannoy Type 1

Established in London in 1926 as the Tulsemere Manufacturing Company, Tannoy initially gained prominence for its public address systems. By the 1940s, the company expanded into microphone manufacturing, introducing the Type 1 ribbon microphone. This model featured a heavy cast iron body and large cylindrical magnets. Type 1 was not adopted by the BBC for broadcast use, as it did not meet their stringent standards compared to higher-end models like the Marconi AX. In their report they wrote:

"In view of the poor performance so far measured, it was decided not to continue the investigation of the Tannoy microphone at present. Inspection of the casing and magnet system suggests that the polar response is not likely to be any better than that of our Type AXB. The instrument has therefore nothing but its small size and weight to recommend it."

In response to feedback, Tannoy made changes to the design while leading to the development of the Type 2 (MR425) model in the early1950s. The MR425 featured a completely new motor design and was smaller in size.

Sensitivity: -74db at 1V / dyne / cm²

Output impedance: 600 ohms (750 ohms measured by the BBC)

MoMics note - the potential of the earliest Tannoy ribbon microphone is limited by the ribbon clamping design which involved putting a screw through the centre of the aluminium foil. This provides a weak point for failure and may be prone to noise due to increased ribbon and clamp resistance.

Xaudia blog post about Tannoy's figure-8 ribbon microphones.

A BBC R&D report from 1947 which investigated this Tannoy ribbon microphone.