The AEA KU4 Supercardioid Ribbon Microphone is a modern replica of the legendary RCA KU3A used for Hollywood movies.

The AEA KU4 is a high-sensitivity ribbon microphone designed to provide all the smooth characteristics associated with ribbon mics with a supercardioid polar pattern offering superior rejection and wider sweet spot. As a result the AEA KU4 can be used in many instances where a traditional figure-of-eight ribbon microphone would pick up too much undesirable sound. A consequence of this unusual polar pattern is a reduced bass proximity effect, meaning that the KU4 can be used for closer mic’ing techniques. A low-tuned, low mass ribbon delivers a frequency response beyond 20kHz and accurate transient response.

The polar pattern on the AEA KU4 is achieved through the use of an acoustical labyrinth made of precision-milled aluminium and filled with material to delay the sound waves at the rear of the ribbon creating frequency-dependent phase cancellation. The rear of the 1.8 micron standard aluminium material is then blocked by a tube feeding into the labyrinth below the ribbon motor creating the necessary delay. The result is a superb supercardioid pattern with clear nulls between 120° to 150° and an attenuation of 24dB at 1kHZ at the 180° point. From 5kHz the polar pattern widens yet still manages to maintain 10dB of reduction at 180°.