User Guide
Using the SF-24 Active Ribbon Microphone™
The head amplification system utilized in the SF-24 was designed to operate with standard 48
volt simplex phantom power sources only. The microphone will not work at all if
phantom
power is not provided to the microphone!
This aspect of an active ribbon microphone is in sharp
contrast to the common wisdom normally applied to ribbon microphones, in which phantom
power usually spells danger or destruction to the ribbon element. Royer’s active series ribbon
microphones require phantom power to operate.
To ensure long service life of your SF-24 active ribbon microphone™, care should be taken
when connecting the microphone to a phantom power source. We have prepared a few tips to
ensure that your SF-24 will perform perfectly for many years. We offer the following
information as a general set of good habits that apply to both active ribbon mics and solid-state
condenser microphones as well.
1. Always be certain to use the SF-24’s five-lead stereo cable, which splits out to two short 3-
pin cables with male XLR connectors labeled “Upper” and “Lower.” Do not substitute
extension cables of unknown wiring! The SF-24’s pin-out is Pin-1 shared ground for both
ribbon transducers, Pin-2 signal hot (in-phase) for the upper transducer, Pin-3 signal cold
(reverse phase) for the upper transducer, Pin-4 signal hot for the lower transducer, Pin-5
signal cold for the lower transducer. If additional extension cables are used, be sure they are
in good serviceable order. Standard microphone cables provide a shielded ground carried
along to Pin-1 and a balanced differential signal carried along Pins-2 and 3, with Pin-2 signal
hot and Pin-3 signal cold.
2. Although it is usually safe to “hot plug” most phantom powered microphones to a
preamplifier or console with the phantom activated, we suggest that if it is possible to
deactivate the phantom power prior to plugging in the microphone, do so. This minimizes
any chance of random voltage surges entering the microphone. More importantly, it reduces
the possibility of loud pops being transmitted to your monitor speakers should the volume
control be raised. Serious damage to your speakers could result from this mistake.
3. Be certain that the input channel fader or volume control is set to minimum before plugging
in any microphone. Preamplifier gain trim should be set to minimum. Plug the microphone in
and activate the phantom power switch. The microphone’s electronics will stabilize in a few
seconds.
4. When the microphone becomes operational, bring the two channel faders to 0-dB (unity) and
use the trims to set the desired level. This technique maximizes the signal-to-noise
performance of the preamplifier or console input channel.
5. When disconnecting the microphone, bring the channel faders down and unplug the
microphone cable ends. It is also advisable to turn off the phantom power before unplugging
the microphone whenever possible.
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