AEA KU4

Supercardioid ribbon microphone

• Passive ribbon microphone with a supercardioid polar pattern
• High rejection of reflections and ambient noise
• Extended high-frequency response with the classic warmth of AEA ribbon microphones
• Designed for near-field applications
• Reduced proximity effect compared to traditional bidirectional ribbon microphones
• Balanced response at distances ranging from approximately 3 to 45 cm
• A modern redesign of the historic RCA KU3A
• Ideal for vocals, percussion, strings, woodwinds, and solo instruments
• Sound pressure handling capacity exceeding 140 dB SPL
• 1.8 μm pure aluminum ribbon element

The AEA KU4 is a passive ribbon microphone with a supercardioid polar pattern, designed to deliver the warmth, naturalness, and harmonic richness typical of ribbon microphones, along with superior control of ambient sound.

The KU4 is a modern reinterpretation of the legendary RCA KU3A and stands out for its versatility in close-up recording. It can be positioned just a few centimeters from the sound source while maintaining a balanced, defined response that is easy to manage in the mix.

Supercardioid polar pattern for greater isolation

Unlike traditional ribbon microphones with a bidirectional polar pattern, the AEA KU4 uses a supercardioid pattern that prioritizes sound coming from the front and significantly reduces reflections and ambient noise in the recording environment.

This feature makes the microphone particularly well-suited for small studios, recording booths, live performances, and situations where it is necessary to better isolate the sound source from other instruments.

High off-axis rejection

The KU4’s polar pattern features maximum rejection at approximately 135°, allowing the microphone to be strategically positioned relative to monitors, nearby instruments, and unwanted reflections.

Rear sensitivity is reduced by approximately 12 dB compared to the front, offering greater focus on the main sound source without completely eliminating the natural sense of space.

Near-field-optimized ribbon microphone

The AEA KU4 is designed to operate at distances ranging from approximately 3 to 45 cm from the sound source. Its controlled proximity effect allows you to position the microphone close to the source without causing an excessive and unmanageable boost in low frequencies.

This feature facilitates placement on individual instruments and allows you to achieve a full, present, and balanced sound right from the recording stage.

Balanced sound even at close range

The KU4 maintains a consistent frequency response even when positioned close to the sound source. The result is a rich and natural recording, with solid low frequencies, detailed mids, and smooth yet well-extended high frequencies.

The ability to position the microphone close to the instrument also reduces room acoustic influence, delivering a more direct and defined signal.

Extended high end and classic AEA character

The AEA KU4 preserves the warmth and musicality that have made ribbon microphones a standard in major recording studios, while adding greater openness in the high frequencies compared to many traditional ribbon models.

The response extends beyond 20 kHz, allowing the microphone to accurately capture transients, articulation, and performance details without introducing harshness or excessive brightness.

Ideal for solo instruments

The AEA KU4 is particularly effective on percussion, strings, woodwinds, vocals, acoustic guitar, amplifiers, and other solo instruments. The combination of a supercardioid polar pattern, controlled proximity effect, and extended frequency response delivers a focused and musical recording.

The microphone is capable of capturing the dynamic and harmonic nuances of the sound source, maintaining a natural and three-dimensional sound.

High Sound Pressure Level Handling

The AEA KU4 can handle levels exceeding 140 dB SPL above 200 Hz, making it suitable even for powerful sources such as guitar amplifiers, brass instruments, percussion, and drum kits.

This wide dynamic range allows the microphone to be used on both delicate instruments and high-volume sources without compromising signal clarity.

Passive Design and Ribbon Transducer

The KU4 is a passive microphone and does not require phantom power. AEA does not recommend using phantom power with this model.

The transducer uses a 1.8 μm-thick corrugated pure aluminum ribbon. Its extremely low mass allows the microphone to respond quickly to changes in the sound source, preserving transients, harmonics, and performance details.

Professional Construction

Its rugged construction and integrated 1.5-meter cable make the AEA KU4 suitable for professional studio use. The microphone comes with a carrying case, a boom arm adapter, and a user manual.

Technical Specifications

• Type: Passive ribbon microphone
• Main application: near-field recording
• Operating principle: pressure gradient transducer
• Polar pattern: supercardioid
• Frequency response: below 30 Hz – above 20 kHz
• Maximum SPL: greater than 140 dB SPL above 200 Hz, with 1% third-harmonic distortion
• Sensitivity: 2.5 mV/Pa, -52 dBV at 1 kHz with an unloaded circuit
• Output impedance: 300 Ω nominal
• Recommended load impedance: 1.5 kΩ or higher
• Phantom power: not required and not recommended
• Polarity: Pin 2 positive for positive pressure on the front side
• Rear-to-front output ratio: -12 dB at 180°
• Maximum rejection angle: 135°
• Diaphragm material: corrugated pure aluminum
• Diaphragm thickness: 1.8 μm
• Diaphragm width: 2.1 mm
• Strip length: 28.6 mm
• Height: 32 cm
• Width: 11.68 cm
• Depth: 9.4 cm
• Weight: 2.15 kg
• Shipping weight: 3.2 kg
• Connector: XLR-3M with integrated 1.5 m cable
• Included accessories: carrying case, boom arm adapter, and user manual