The SF-24V vacuum tube stereo ribbon microphone is the pinnacle of Royer's SF-series stereo microphones. The sound pickup is lush, smooth and natural, with outstanding stereo imaging and superb transient response. The tube electronics provide increased midrange reach, unmatched clarity and detail, and an airiness previously unheard of in ribbon mics. Utilizing the same proprietary tube electronics as in Royer's TEC Award-winning R-122V ribbon microphones, the SF-24V delivers the ultimate in stereo ribbon miking for the true connoisseur of recorded sound.

The SF-24V's independent tube circuits provide an output level of –38dB, suitable for use with any professional preamplifier. With self-noise of lower than 18dB, the SF-24V's ultraquiet operation is suitable for the most demanding classical and acoustic recording applications.

Like an SF-12, the SF-24V is actually two matched ribbon microphones, placed one above the other in a coincident pair, each aimed 45 degrees from center in the classic Blumlein configuration. The magnet/pole piece structure of each ribbon transducer delivers a wide, uniform frequency response with no substantial peaks or dips, and the 1.8-micron ribbons produce superb transient response. Frequency response is excellent regardless of the angle of sound striking the ribbons and off-axis coloration is negligible.

The Electronics
The SF-24V's twin-head amplifiers consist of low-noise, triode-connected military-grade 5840 vacuum tubes. Designed for a wide range of applications, the SF-24V delivers –38dB output and the drive capabilities only vacuum tube head amplifiers can provide. The circuits are devoid of typical vacuum tube coloration.

The SF-24V's triode-configured cathode follower circuitry enables the microphone to drive long cable runs without sonic degradation or high-frequency loss. This capability is further enhanced by the SF-24V's dedicated power supply, which provides ample current to the vacuum tube electronics. Induced noise is virtually eliminated by the microphone's fully balanced outputs, which are electrically isolated with special purpose Jensen output transformers.

The SF-24V has far more level than non-powered ribbon microphones and its impedance matching circuitry places a perfect load on the ribbon element at all times. This allows the use of a wide variety of mic preamps without concern for gain and impedance matches, two critical issues with ribbon microphones. In addition, the microphone's electronics shield the ribbon elements from any possibility of damage by phantom power, electrical glitches or miswired cables.

It is important to note that the SF-24V's higher sensitivity creates no additional self-noise. All of the SF-24V's increased level comes from its large, specially wound toroidal transformers, so there is no additional noise associated with the microphone's higher output. The tube system operates at less than unity, adding no noise of its own.