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AEA KU4 Unidirectional Ribbon Microphone with a Supercardioid Pattern - B-Stock

by AEA
Save 33%
Original price £5,758.56 inc. vat
Current price £3,838.80 inc. vat
£3,199.00 ex. vat
Please contact us for availability.

AEA KU4 - Unidirectional Ribbon Microphone - B-Stock

The  AEA KU4 is an ultra detailed ribbon microphone that provides the user with a smooth sound when capturing vocals and strings. This microphone features a lightly-tensioned, low mass ribbon with a frequency response beyond 20 kHz, an accurate transient response, and no upper midrange resonances common to large condenser mics meaning you get a clear accurate sound so you will have little to change in post. The feature of a supercardioid polar pattern instead of a figure-eight means this mic is set apart from other ribbon mics allowing you to use it for different applications.

This is a B-Stock, Ex-Demo item.

The KU4's suppressed rear lobe reduces the pickup of room ambience and is especially useful when the rear of a figure-eight pattern would pick up undesirable sounds. The KU4's reduced bass proximity effect facilitates closer miking, while its low-tuned ribbon does not exhibit bass distortion. These characteristics make the KU4 well-suited for the modern studio. It is currently the only supercardioid ribbon microphone in commercial production.

The KU4 is a re-vision of the legendary RCA KU3A, a unidirectional microphone originally designed for the Hollywood movie studios. Also known as the “10001” (for its RCA manufacturing number), it was RCA’s most expensive ribbon microphone and fewer than 600 units were ever manufactured. The KU3A combined the smooth ribbon sound of a 44 with a unidirectional pattern, a wide sweet spot, and reduced proximity bass boost. Expanding an engineer's variety of placement choices, it became a standard at film studios around the world.

AEA KU4 Features

Unidirectional (supercardioid) pickup pattern
Reduced proximity effect and room ambience
Extended top end with classic ribbon smoothness
Modern, consistent version of the RCA KU3A


  • Operating Principle: Pressure gradient microphone
  • Directional Pattern: Supercardioid
  • Frequency Range: Below 30 Hz to 20 kHz
  • Maximum SPL: 140+ dB SPL (1% third harmonic > 1 kHz)
  • Output Sensitivity: 2.8 mV/Pa (-51 dBV) into unloaded circuit
  • Output Impedance: 300 Ohms nominal
  • Recommended Load Impedance: 1.2 kOhms or greater
  • Polarity: Pin 2 high for positive pressure at the front of the microphone
  • Connector: XLR-3M wired to a 1.5 meter captive cable
  • Off Axis Response (Vertical): Level changes with angle, reduced HF response above and below 0° / 180° axis
  • Ribbon Thickness: 1.8 microns (.0000018 meter) of pure aluminium
  • Ribbon Width: 0.082” (2.1 mm)
  • Ribbon Length: 1.25” (28.6 mm)
  • Limited Warranty: One year parts and labour, shipping not included. Three year extended warranty if the product is registered.
  • Weight with Cable: 4 lb 11 oz (2.15 kg)
  • Weight with case: 7 pounds (3.2 kg)
  • Height: 12.65” (32.4 cm)
  • Width: 4.62” (11.7 cm)
  • Depth: 3.75” (9.5 cm)