Royer Labs SF-2 is a compact, monaural, phantom-powered active ribbon microphone — the active successor to the passive SF-1, designed primarily for classical recording, scoring stages, and acoustic instruments. At the core of the microphone is a proprietary crossfield motor assembly: four Neodymium magnets with Permendur iron pole pieces arranged in a geometry that minimizes the front-to-rear acoustic path length inside the capsule, which directly extends the high-frequency ceiling of the design. The 1.8-micron aluminum ribbon element's low mass delivers fast transient response. Twenty SF-2 prototypes circulated in major studios and scoring stages for years prior to the microphone's commercial release, establishing its reputation in classical and orchestral recording circles before the product ever appeared in a catalog. Active electronics deliver -38 dB sensitivity, placing the SF-2 on par with phantom-powered condenser microphones.
Crossfield motor assembly — architecture built for high-frequency extension
In a conventional ribbon motor, the ribbon is suspended between two pole pieces and the front-to-rear acoustic path length constrains high-frequency response. The SF-2's crossfield motor solves this differently: four Neodymium magnets surrounding the ribbon with Permendur iron pole pieces minimize the effective acoustic path to the shortest possible distance, allowing a flat frequency response across 30 Hz – 15 kHz +/- 2 dB without artificial high-frequency boost. The 1.8-micron ribbon's low mass produces fast transient response — audible on strings, woodwinds, and percussion. The stainless steel body forms part of the magnetic return circuit, actively containing stray flux, which matters when the microphone is positioned near other sensitive equipment on a recording session.
Active electronics and preamp independence
The SF-2's active electronics — identical in architecture to the R-122 and SF-24 — consist of a custom toroidal step-up transformer delivering 14 dB of free gain, followed by an active impedance conversion stage operating below unity gain and contributing no noise of its own. Self-noise is below 18 dB. The circuit maintains constant, optimal impedance loading on the ribbon element regardless of the downstream preamp's input characteristics — the SF-2 performs equally with a broadcast console and a studio tube preamplifier. The 200-ohm output impedance supports long cable runs without HF loss. The ribbon element is fully protected against phantom power, miswired cables, and electrical transients. Primary applications: choir and orchestra, classical piano, strings, woodwinds, harp, acoustic guitar, mandolin, ambient miking, voice-over. The symmetrical figure-eight pattern enables use as the Side microphone in an M/S array. Lifetime warranty to original owner; first ribbon replacement free.
KEY FEATURES
- Compact, monaural active ribbon microphone, phantom powered
- Proprietary crossfield motor: 4x Neodymium magnets + Permendur pole pieces — minimal acoustic path, maximum HF extension
- 1.8-micron aluminum ribbon — low mass, fast transient response
- Active Ribbon electronics: -38 dB sensitivity — condenser microphone output level
- 14 dB free gain from toroidal transformer — zero added noise from active circuit
- Self-noise below 18 dB
- Constant optimal ribbon load impedance regardless of preamp characteristics
- 200-ohm output — long cable runs without HF loss
- Flat frequency response: 30 Hz – 15 kHz +/- 2 dB
- Negligible off-axis coloration; consistent response regardless of incidence angle
- Symmetrical figure-eight — usable as Side microphone in M/S configurations
- Stainless steel body with internal baffle and damper; low external magnetic leakage
- Gold-plated XLR output connector
- Ribbon element protected from phantom power, miswired cables, and electrical transients
- Lifetime warranty to original owner; first ribbon replacement free
TECHNICAL SPECIFICATIONS
- Acoustic operating principle: electrodynamic pressure gradient with active electronics
- Polar pattern: figure-8
- Generating element: 1.8-micron aluminum ribbon
- Motor assembly: crossfield — 4x Neodymium magnets + Permendur iron pole pieces
- Frequency response: 30–15,000 Hz +/- 2 dB
- Sensitivity: -38 dBv re. 1V/Pa
- Self-noise: below 18 dB
- Output impedance: 200 ohms @ 1 kHz
- Rated load impedance: above 1,500 ohms
- Maximum SPL: above 130 dB
- Output connector: XLR 3-pin (Pin 2 Hot), gold-plated
- Power requirements: 48V phantom, 4 mA
- Dimensions: 142 mm (L) x 39 mm (base) x 25 mm (top)
- Weight: 448 g (15.8 oz)
- Finish: Matte Black
- Includes: SF-2 microphone, SFS-2 shockmount, mic sock, aluminum carrying case
