AEA KU4

The AEA KU4 is an homage to the RCA KU3A, taking inspiration but updating the design with modern technologies. These updates include neodymium magnets rather than AlNiCo, a fiberglass-filled labyrinth rather than horse hair, Cinemag transformer, and a baffle for low frequency control. The AEA KU4 is distinct from other ribbon mics in that it has a super-cardioid polar pattern, making it ideal for stage and full band recordings.

The KU4 is a surprisingly bright microphone for being a ribbon, due to its motor design, baffle system, and super-cardioid polar pattern. It shines on a variety of sources, but is particularly a favorite on stand-up bass. The super-cardioid polar pattern is achieved by blocking the back (negative) polarity of the ribbon, with the exception of a small aperture, and sending the sound that travels through the ribbon gap down into an acoustical labyrinth, which basically acts like a little anechoic chamber to prevent resonances behind the ribbon. 

• Operating Principle: Pressure gradient transducer
• Directional Pattern: Supercardioid
• Frequency Range: <30 Hz to >20 kHz
• Maximum SPL: 140+ dB SPL above 200 Hz for 1% third harmonic
• Sensitivity: -52dBV (2.5 mV/Pa) (at 1 kHz into unloaded circuit)
• Output Impedance: 300 Ω nominal
• Load Impedance: 1.5 kΩ or greater
• Phantom Power: Not required or recommended
• Polarity: Pin 2 high for positive pressure on front of mic
• Off Axis Response: Relative Output: -12 dB at 180°
• Angle of Max Rejection: 135°
• Transducer Element: Pure aluminum corrugated ribbon, thickness 1.8 µm, 0.082 in (2.1 mm) x 1.25 in (28.6 mm)

Thanks to Joey Krieger and Paul Pegas at AEA for additional information.

The official AEA KU4 web page.

View the AEA KU4 owner's manual.

A review of the AEA KU4 ribbon microphone by Sound on Sound magazine.