Royer Labs SF-12

Royer Labs SF-12 is a passive stereo coincident ribbon microphone, hand-built in Burbank, California. A single enclosure – dimensionally identical to the mono R-121 – houses two matched ribbon transducers arranged in the classic Blumlein configuration: each rotated 45 degrees from the vertical axis, stacked one above the other. The SF-12 is based on Bob Speiden's original design, developed by Royer Labs with improved toroidal transformers and a lower-mass ribbon.

Blumlein on One Stand – Geometry Two Separate Mics Cannot Replicate

The Blumlein technique requires zero acoustic distance between two figure-8 elements crossed at 90 degrees. Two separate microphones can never fully satisfy this requirement due to the physical offset between their housings. The SF-12 solves this structurally: both ribbons share the same vertical axis, eliminating inter-channel phase delay and delivering stereo imaging with exceptional depth and mono coherence. Summing both channels to mono produces no phase artifacts – the SF-12 can be collapsed to mono in a mixer without consequence. The lower element is the left channel, the upper the right, referenced from the rear of the microphone.

Passive Ribbon in Studio and Live Applications

The absence of internal active electronics means there is no circuit inside the microphone capable of overloading regardless of SPL – the 130 dB ceiling is a mechanical ribbon limit, not an electronic one. The 1.8-micron aluminium ribbons at approximately 1/3 milligram each respond to transients with an accuracy unavailable from higher-mass condenser diaphragms. High-efficiency toroidal transformers with a gold-plated 5-pin XLR output connector – with a Y-cable splitting to two standard XLRs included in the box – deliver low self-noise and a stable 300 Ω output impedance. The ingot iron case forms part of the magnetic return circuit, minimising flux leakage and contributing to the relatively high sensitivity in a compact package.

KEY FEATURES

• Two matched ribbon transducers in 90° Blumlein configuration – coincident stereo from one stand position
• Full mono compatibility – channel summing without phase artifacts
• M-S recording possible by re-routing channels
• No internal active electronics – no electronic overload up to maximum SPL rating
• 1.8-micron aluminium ribbons, approx. 1/3 mg each – exceptional transient response
• High-efficiency toroidal transformers with gold-plated 5-pin XLR output connector
• Ingot iron case – forms part of the magnetic circuit, very low flux leakage
• 5-pin XLR to dual 3-pin XLR Y-cable (Upper / Lower) included
• Ribbon element unaffected by temperature and humidity changes
• Hand-built in Burbank, CA

TECHNICAL SPECIFICATIONS

• Acoustic operating principle: electrodynamic pressure gradient (passive)
• Polar pattern: symmetrical figure-8 (both elements)
• Generating element: 1.8-micron aluminium ribbon
• Frequency response: 30–15,000 Hz ±3 dB
• Sensitivity: >-52 dBV re. 1 V/Pa
• Output impedance: 300 Ω @ 1 kHz (nominal)
• Rated load impedance: >1500 Ω
• Maximum SPL: >130 dB
• Output connector: 5-pin male XLR (stereo)
• Dimensions: 206 mm L x 25 mm W
• Weight: 369 g (13 oz)
• Finish: matte black chrome (standard) / dull satin nickel (optional)