Royer Labs SF24

Royer Labs SF-24 is a phantom-powered active stereo ribbon microphone — a direct counterpart to the passive SF-12, with Royer's proprietary Active Ribbon electronics built in. Two matched 1.8-micron aluminum ribbon transducers are mounted one above the other in a true coincident Blumlein configuration, each aimed 45 degrees off center, delivering a single-point stereo capture with crossed figure-eight patterns. Ultra-low noise FET circuits and custom-wound toroidal transformers provide a sensitivity of -38 dB, placing the SF-24 on par with phantom-powered condenser microphones. Royer Labs is a Grammy Award recipient, recognized for their contributions to ribbon microphone technology.

Active electronics eliminate the preamp problem

Passive ribbon microphones require 15–30 dB more gain than condensers and are sensitive to preamp input impedance — improper loading results in loss of low end, diminished body, and reduced sensitivity. The SF-24 resolves both issues at the source: two fully balanced, discrete head amplifier systems per capsule maintain a constant, optimal load on each ribbon element regardless of what follows in the chain. The higher output level is not the result of an amplification stage — the active circuit operates below unity gain, with the increased sensitivity coming entirely from the high-efficiency toroidal transformers (free gain). Self-noise remains below 18 dB, unchanged despite the higher output. The low-impedance output (200 ohms) allows for very long cable runs without high-frequency loss, and the ribbon elements are fully protected against phantom power, miswired cables, and electrical transients.

Recording configurations and applications

The SF-24 supports two coincident stereo techniques from a single mic position: classic Blumlein (two figure-eights at 90 degrees) and M/S — requiring only matrix processing in the console or DAW. Each channel can be used independently as a standalone mono figure-eight microphone; phase compatibility between the two channels is complete, allowing stereo-to-mono summing without artifacts. Off-axis coloration is negligible — frequency response stays consistent regardless of the angle of the incoming sound. Primary applications include full orchestra and choral recording, classical piano, drum overheads, acoustic instruments of any kind, vocal ensembles, and room ambience capture. The microphone ships with an extension cable terminating in a Y-splitter to two standard 3-pin XLR connectors, labeled Upper and Lower for the respective capsules.

KEY FEATURES

• Two matched 1.8-micron aluminum ribbons in Blumlein configuration (crossed figure-eights, 45° off axis)
• Active Ribbon electronics: -38 dB sensitivity — on par with phantom-powered condenser microphones
• Two discrete head amplifier systems with high-efficiency toroidal transformers (free gain)
• Self-noise below 18 dB — no increase despite higher sensitivity
• Constant optimal ribbon load impedance regardless of preamp characteristics
• 200-ohm output impedance — suitable for long cable runs without HF loss
• Ribbon elements protected against phantom power, electrical transients, and miswired cables
• Supports Blumlein and M/S configurations from a single mic position
• Each channel usable independently as a mono figure-eight microphone
• Full phase compatibility — stereo summing to mono without artifacts
• Negligible off-axis coloration; consistent frequency response regardless of angle
• Maximum SPL above 130 dB with no distortion
• Power: 48V phantom only, 4 mA per channel
• Includes: extension cable with Y-splitter (XLR5 to 2x XLR3), Sling-Shock shockmount

TECHNICAL SPECIFICATIONS

• Acoustic operating principle: electrodynamic pressure gradient with active electronics
• Polar pattern: crossed figure-eights (Blumlein)
• Generating element: 1.8-micron aluminum ribbon
• Frequency response: 40–15,000 Hz +/- 2 dB
• Sensitivity: -38 dB (re. 1V/Pa +/-1 dB)
• Self-noise: below 18 dB
• Output impedance: 200 ohms
• Rated load impedance: 1k ohm
• Maximum SPL: above 130 dB
• Output connector: male XLR 5-pin (stereo)
• Power requirements: 48V phantom only, 4 mA per channel
• Dimensions: 270 mm x 39 mm (base) x 25 mm (top)
• Weight: 583 g (20.5 oz)
• Finish: Optical Black; optional 18K Gold