AEA R44CX

AEA R44CX is a passive ribbon microphone — a museum-quality replica of the RCA 44BX with the X-Motor modification. Two additional neodymium magnets in the motor increase output by 6 dB over the R44C and the original RCA 44BX with no active electronics. All mechanical and acoustic components — the 1.8-micron ribbon at 59.7 mm × 4.7 mm made from material produced for RCA, the transformer, the motor parts — are interchangeable with an original 1936–1938 RCA 44BX. The R44CX is externally identical to the R44C (bronze investment cast yoke, hand-polished cushion mount, cloth-covered Accusound Silver Studio Pro cable) and distinguished only by a red badge in place of the black-and-silver one.

X-Motor and 4.47 mV/Pa — Wide Dynamic Range Without Active Electronics

The X-Motor modification — invented by AEA — adds two permanent magnets to the ribbon motor, raising sensitivity from 2.25 mV/Pa (R44C) to 4.47 mV/Pa (–47 dBV), a 6 dB increase with no change in tonal character. The undamped, long ribbon at 59.7 mm tuned to 16.5 Hz — the longest and lowest-tuned ribbon in current production — preserves full dynamic headroom without clip at SPLs above 165 dB. In practice the higher output translates to better SNR on quiet sources, a wider dynamic range in scoring and orchestral sessions, and broader preamp compatibility without specific high-impedance or high-gain requirements. The tonal character — rich low end, relaxed top, smooth midrange with a characteristic 2 dB/octave tilt from low to high — is unchanged from the R44C.

Museum-Grade Construction and Preamp Requirements

The bronze investment cast yoke is superior to the original RCA zinc yokes, which corrode over decades. The cushion mount is hand-polished; the cable is cloth-covered Accusound Silver Studio Pro. The R44CX requires no phantom power — 48 V can damage the ribbon. Sensitivity of 4.47 mV/Pa and 270 Ω output impedance still require a preamp with at least 60 dB of gain and input impedance above 1.2 kΩ, though the higher X-Motor output broadens compatible preamp options compared to the R44C. The microphone ships with a 3-meter captive cable, an AEA 44VC vertical carrying case, and a zippered canvas bag.

KEY FEATURES

• Passive RCA 44BX replica with X-Motor modification (+6 dB output vs. R44C)
• 1.8-micron aluminum ribbon — 59.7 mm × 4.7 mm, ribbon material originally produced for RCA
• Undamped ribbon design — 16.5 Hz resonant tuning, longest ribbon in current production
• Polar pattern: figure-8 (bidirectional)
• Max SPL: 165+ dB (1% THD harmonic distortion >1 kHz)
• Sensitivity: 4.47 mV/Pa (–47 dBV) into unloaded circuit
• Output impedance: 270 Ω broadband
• Recommended load impedance: ≥1.2 kΩ
• Phantom power: not required or recommended
• All parts interchangeable with original RCA 44BX
• Bronze investment cast yoke, hand-polished cushion mount
• Red badge distinguishes X-Motor version from standard R44C
• 3 m cloth-covered Accusound Silver Studio Pro captive cable, XLR-3M
• Accessories: AEA 44VC vertical case, zippered canvas bag
• Dimensions: 311 mm (H) × 117 mm (W) × 83 mm (D); weight: 3.43 kg with cable
• Handmade in Pasadena, California, USA

TECHNICAL SPECIFICATIONS

• Operating principle: pressure gradient transducer (passive, undamped)
• Polar pattern: figure-8 (bidirectional)
• Frequency range: <20 Hz – >20 kHz
• Max SPL: 165+ dB (1% THD >1 kHz)
• Sensitivity: 4.47 mV/Pa (–47 dBV) into unloaded circuit
• Output impedance: 270 Ω broadband
• Recommended load impedance: ≥1.2 kΩ
• Phantom power: not required or recommended
• Polarity: Pin 2 + for positive pressure at front
• Off-axis rejection: up to 90 dB at 90°/270° (horizontal)
• Ribbon thickness: 1.8 µm; width: 4.7 mm; length: 59.7 mm
• X-Motor modification: +2 magnets, +6 dB output vs. R44C
• Connector: XLR-3M on 3 m cloth-covered Accusound Silver Studio Pro captive cable
• Dimensions: 311 mm (H) × 117 mm (W) × 83 mm (D)
• Weight: 3.43 kg (with cable)
• Made in: USA (Pasadena, CA)