Off-axis frequency response in a dual diaphragm, uniphase moving coil microphone

Abstract

When the rear port in a uniphase, unidirectional condenser microphone is modified to include a series compliance element (dual diaphragm) the low frequency performance can be improved. The benefit is most notable in the off-axis response as it relates to source/receiverproximity (proximity effect). Due to the significant operational differences between uniphase moving coil and condenser microphones, incorporating a dual diaphragm element into the rear port of a moving coil microphone requires careful attention to the design. Simplified network models of the uniphase system, proximity effect, and dual diaphragm moving coil design are presented. Measured results of a dual diaphragm, uniphase moving coil microphone are presented with off-axis response comparisons to a single diaphragm, uniphase moving coil microphone.