Royer Labs
Model SF-24
Stereo Active Ribbon Velocity Microphone
Operation Instructions Manual
& User Guide
Made in U.S.A.
Model SF-24 Ribbon Microphone
Revised 2015
Active Ribbon Technology
Ribbons in the Digital World
User Guide
Using the SF-24 Active Ribbon Microphone
Using the RSM-24 Shock Mount Accessory
Properly Inserting the Microphone into the Shock
Removing the Microphone from the Shock
Connecting the SF-24
Amplification Considerations
Stereo Microphones and Ground Loops
Equalization and Ribbon Microphones
Hum, Noise and Mic Orientation
Microphone Techniques
General Tips for Using the Royer SF-24
Specialized Stereo Recording Techniques
Classic Blumlein Technique
Mid-Side (M-S) Technique
Care and Maintenance
Care for the Optical Black Finish
Wiring Diagram
Polar Pattern
Frequency Response
Congratulations on your purchase of a Royer Labs model SF-24 stereo active ribbon
microphone. The SF-24 is a handcrafted precision instrument capable of delivering superior
sound quality and exceptional performance. The SF-24 represents a new level of performance for
ribbon microphones, combining sophisticated technological advancements with old-world
craftsmanship. The SF-24 incorporates two independent head amplification systems that operate
on standard 48-volt phantom power, similar to standard condenser microphones. This enables the
SF-24 to deliver the same sensitivity that the recording industry has grown accustomed to with
modern condenser microphones. In addition, the active circuitry completely isolates the ribbon
element from impedance mismatches, short circuits and other anomalies that can degrade
microphone performance or damage the sensitive ribbon element. The SF-24 breaks the longstanding taboo associated with ribbon microphones and phantom power; it actually requires
phantom power to operate.
This instruction manual describes the SF-24, its function and method of use. It also describes the
care and maintenance required to ensure proper operation and long service life. The User Guide
section of this manual offers practical information designed to maximize the performance
capabilities of this microphone.
Royer Labs products are manufactured to the highest industrial standards using only the finest
materials obtainable. Your model SF-24 went though extensive quality control checks before
leaving the factory. Normal care is all that is required to assure a lifetime of trouble-free service.
Please read this manual thoroughly in order to become familiar with all of the SF-24’s
capabilities. It will assist you in making the most of your microphones’ superior acoustic
properties. This manual is a handy reference guide and we suggest you refer to it whenever
questions arise on the use and care of your SF-24 ribbon microphone.
Active Ribbon Technology
The heart of the SF-24 is its proprietary electronic system consisting of specially designed
toroidal transformers and electronic buffering stages. This system provides excellent frequency
response, extremely low noise and distortion, and high SPL handling (130 dB) without the use of
pads. It gives the SF-24 an output level comparable to that of condenser microphones, and its
buffer stages provide a low impedance output and present a perfect impedance load to each of
the ribbon elements. Unpowered ribbon microphones suffer substantially degraded frequency
response and lowered gain when they are paired to a preamp with too low an input impedance.
With the SF-24‘s active electronic system, the microphone’s frequency response and output are
much less affected by variations in the input impedance of the following preamp.
Sonically the SF-24 differs from the unpowered SF-12 in one subtle way; due to the extra iron in
the SF-24’s much larger transformers, low-end frequencies sound slightly tighter and more
Key Points:
No longer is it necessary to mate a ribbon microphone to an ultra-high gain, low noise
preamplifier for optimum performance. Any preamplifier of nominal gain will provide good
results with the SF-24.
No longer is it necessary to carefully consider impedance matching characteristics when
choosing a preamplifier. Microphone loading is a non-issue and consistent performance is
assured, regardless of the preamplifier’s impedance characteristics.
No longer is it necessary to be concerned about damaging the ribbon element with phantom
power. The active electronics need phantom power to operate - a first for ribbon
No longer is it necessary to worry about the effects of long cable runs degrading the
performance of your ribbon microphone. The active electronics provide a robust low
impedance signal that can handle long cable lengths with minimal loss of signal.
The SF-24 stereo coincident active ribbon microphone is the only microphone of its kind
available, combining high audio performance with outstanding separation and imaging. It is a
modern ribbon design, with no audible diffraction effects or cavity resonance. The SF-24's active
electronics produce an output comparable to phantom powered studio condenser microphones
and because the ribbon elements are electronically isolated from the outside world, the
possibility of ribbons becoming damaged as a result of faulty wiring, brownouts or phantom
power supply defects is virtually eliminated.
The SF-24 is a compact, stereophonic ribbon microphone array consisting of two matched
microphone elements that are placed one above the other. Each transducer is positioned at 45
degrees to the left and right of center, or 90 degrees from each other. When held vertically,
connector down and the “ROYER” logo facing the sound source, the upper element is the right
channel and the lower element is the left channel, from the perspective of an observer behind the
mic. The microphone elements are each bidirectional (figure-8) and may be addressed from
either side with equal sensitivity. The in-phase signals are achieved when the microphone is
addressed from the front, as indicated by the “ROYER” logo. If, however, the microphone is
suspended upside down, the connections to the preamplifier should be reversed since what was
the left transducer is now responding to signals from the right and vice versa.
Your SF-24 is equipped with a 5-pin XLR type extension cable and a splitter cable that fans out
to twin 3-pin male XLR connectors. As shipped from the factory, the connectors are marked
“upper” and “lower,” since referring to them as "left” and “right” could lead to confusion.
The SF-24 is reasonably tolerant of shock and vibration, but care should be taken to prevent
accidental stretching of the ribbon elements. This is covered in the Care & Maintenance section
of this manual. The performance of the microphone is unaffected by changes in temperature or
The SF-24 is a highly versatile microphone, ideally suited for a wide range of critical recording
applications. From drums, acoustic stringed instruments and stereo vocals to ensembles like big
band, orchestra and jazz groups, your SF-24 will capture performances with uncanny realism and
a beautifully full stereo image.
Because of the SF-24’s coincident crossed figure-8 pattern, M-S (mid-side) recording from one
microphone is easily achievable. Once a recording has been completed using the proper
orientation, the sound field can be adjusted from pure monophonic to “super wide.”
Although spaced microphones can produce similar stereophonic results, such recordings when
summed to mono can suffer from “comb filter” effects: peaks and dips in the frequency response.
When the SF-24 is used for M-S recording, the feeling of space changes but the sonic quality
does not. For more detailed information on the M-S technique, see the chapter Recording
Techniques: Mid-Side (M-S) Recording in this manual.
The SF-24’s small size and optical black chromium finish create minimal disturbance in the
visual field, which is especially important when the microphone must not obstruct the view of an
audience or of a motion picture or TV camera.
Ribbons in the Digital World
Digital recordings benefit greatly from the properties inherent in ribbon microphones. Since A to
D converters cannot distinguish between the sound source being recorded and the complex
distortion components often associated with condenser microphones, they sometimes have
difficulty tracking the signal, resulting in ringing and edgy-sounding tracks. With ribbon
microphones, ringing is almost nonexistent due to the ribbon’s lack of distortion artifacts and
high frequency peaks. A to D converters have less difficulty tracking the ribbon generated signal,
resulting in very smooth digital recordings free of microphone-related edginess.
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 3pin 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
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.
6. If the studio has the microphone lines brought to a patch bay (tie lines), never crosspatch a
microphone line when phantom power is applied or the monitor volume is raised. This could
cause damage to your microphone, preamplifier or monitor speakers.
There are a few important facts that are key to understanding how to use ribbon microphones
1. With ribbon microphones, rejection in the “dead” areas is very strong. Due to this
directionality, ribbon mics should be placed at 1.3 times the distance normally used with
omni-directional microphones, or at approximately the same distance used for cardioid
microphones. This method is used to achieve the same ratio of direct to reflected sound.
2. In the horizontal plane, ribbon microphones do not discriminate against the “highs” off axis,
nor do they boost them on axis. Therefore, several instruments or vocalists can be placed in
front of the microphone without favoring the performer in the center of the group.
Several performers can be grouped at both the front and the back of the microphone, with
one proviso: Since the outputs are out of phase at the front and back of the microphone,
cancellation can result if two tenors are placed on opposite sides at equal distances and are
singing in unison. Therefore, listen to the feed before committing to it.
3. The Royer model SF-24 is a phantom powered microphone and must be connected to a
preamplifier or console cable of delivering 48-volts at a minimum of 4-milliamperes per
channel. Faulty or improperly wired cables could cause your SF-24 to become inoperative.
Since the active electronics offer electrical isolation to each ribbon, miswired cables should
not cause damage to the ribbons themselves.
4. Never attempt to “test” the SF-24 (or any ribbon microphone) with an ohmmeter. Damage to
the delicate electronics could occur.
Always provide adequate protection for your SF-24 (or any ribbon microphone). If the
microphone is to remain set up on a stand when not in use, place a “mic sock” (provided)
over it until it is to be used. As even light wind can stretch the SF-24‘s ribbon elements, do
not carry the microphone around without placing a mic sock over it. Failure to follow this
commonsense practice may yield a stretched ribbon and compromised performance!
5. Avoid dropping the microphone. An accidental fall to a hard surface could stretch one or both
ribbons and, depending on the nature of the fall, possibly require a complete overhaul of the
Using the RSM-24 Shock Mount Accessory
Your SF-24 is supplied with a Royer RSM-24 suspension type shock mount designed specifically
for this microphone. The RSM-24’s specially formulated polymer mounts provide maximum
isolation from shock and vibration while holding the SF-24 securely in place, allowing the
microphone to be safely positioned at any angle.
The RSM-24’s Delrin support tubes are relieved on the inside to minimize contact with the
microphone. Teflon strips are bonded to the inside of the Delrin tubes and serve as a means to
slide the microphone in and out of the shock. It is normal for the Teflon strips to develop wear
marks with repeated use.
The shock easily accommodates standard 5/8"-27 female microphone stand threads. The support
frame is machined from solid T-6 hard aluminum, then black anodized for long life and a clean
unobtrusive appearance. The clutch mechanism provides easy positioning of the shock with
minimal pressure. There is also a relief button that enables the clutch handle to be repositioned
out of the way.
The shock mount has two orientation slots for easy X-Y and M-S positioning. The X-Y slot faces
forward and the M-S slot is 45 degrees to the left.
It is important to use the RSM-24 shock mount correctly. Making sure that the microphone is
inserted properly into the shock mount will minimize any chance of the mic coming loose and
will assure proper orientation of the transducer elements. It is also important to make certain that
the mic is inserted and removed gently to avoid unnecessary shock to the ribbons.
Properly Inserting the Microphone into the Shock
Examine the shock carefully. Observe that the upper Delrin support tube has one slot inside the
tube that faces forward, the same direction as the logo, and one slot
that faces 45 degrees to the left of center. The forward slot is used to
orient the center, on-axis position of the microphone. This is critical
in establishing accurate left/right (X-Y) positioning relative to the
sound source. The microphone is inserted in such a manner that the
"ROYER" logo on the microphone nestles comfortably in this slot.
The 45 degrees left of center slot is used to orient the microphone
for M-S recording. With the microphone logo inserted in this slot,
the upper ribbon element faces forward for the "Mid" signal and the
lower ribbon element faces sideways for the "Side" signal. (Figure
Hold the mic by placing the transducer (ribbon element) end in the
palm of one hand. While holding the shock mount in the other hand,
Figure 1
gently insert the microphone's base into the upper tube first. Be sure
that the logo on the microphone aligns itself with the slot in the
upper support tube as you feed the mic through. (Figure 2) Continue
to feed the microphone through the upper tube and into the lower
tube where it will stop when it reaches the lip at the bottom of the
lower tube. Do not force or jerk the microphone into position!
Removing the Microphone from the Shock
Removal is simply the reverse process. Firmly grip the microphone
with one hand and gently slide it out of the shock. (Figure 3) It may
help to gently push from the bottom of the microphone while
removing it from the lower tube. Again, be sure not to force or jerk
the microphone. Ribbon elements are sensitive to abrupt shocks and
blasts of air, so be gentle.
Figure 2
If, after a time, body oils or other contaminants make it difficult to
insert or remove the microphone from the shock mount, a small
amount of talc can be used to "lubricate" the microphone housing.
Use talc very sparingly and do not let any of it get into the ribbon
transducers, as it can compromise the ribbons’ performance.
Connecting the SF-24
The SF-24 is supplied with a cable set consisting of a 25-foot, 5-pin
male/female XLR microphone cable and a separate Y type splitter
Figure 3
cable. The splitter cable converts the stereo signals from the
microphone cable to a pair of standard 3-Pin male XLR plugs that
provide the RIGHT and LEFT signals to a stereo or two-channel
preamplifier. With the microphone positioned upright (logo facing sound source), the UPPER
element is RIGHT and the LOWER element is LEFT, as viewed from the observer's perspective.
The splitter cables are labeled UPPER and LOWER rather than RIGHT and LEFT to avoid
confusion when the microphone is suspended upside down.
Although the active electronics are robust and the ribbon elements are electronically isolated
from the outside world, it is wise to make all your electrical connections prior to activating
phantom power. Avoid cross-patching any microphone tie lines with phantom power activated, as
this is equivalent to having a momentarily "defective" cable as the patching cords are inserted.
This not only stresses the microphone's electronics but can harm a phantom power source and
produce loud thumps in your speakers.
Since the SF-24 is active, its low impedance output allows for long cable runs with minimal
affect on the microphone’s performance. High frequency response losses and noise pickup will
be minimal even with cable runs up to several hundred feet.
Amplification Considerations
Almost any stereo microphone preamplifier (or pair of mono preamplifiers) with nominal gain
characteristics and built in 48-volt phantom power sources will give excellent results with your
SF-24 active ribbon microphone. Unlike standard ribbon microphones, which depend on a proper
impedance match to deliver optimal performance, the input impedance of your preamplifiers will
have minimal affect on the SF-24’s performance because the ribbon elements are loaded
perfectly via the microphones’ internal electronics.
Careful consideration should be given to the quality of the microphone preamplifier. Studio grade
preamplifiers usually sound much better than cheaper ones. Headroom, noise floor, transparency
and coloration are all factors to consider in determining which preamplifier is suitable for your
studio or live applications. Other features are usually secondary and fall into the category of
conveniences or interface capabilities (such as digital or optical outputs).
A good preamplifier should sound natural, with no sign of edginess or excessive noise. Vacuum
tube preamplifiers sound warm, yet wonderfully airy and transparent. Do not expect a vacuum
tube preamplifier to be as quiet as a solid-state preamp, as electron emissions from tubes tend to
convey more “thermal” noise than transistors. Tube preamplifier noise is far less of an issue with
the SF-24 than with conventional ribbon microphones because the SF-24’s high output will
override the noise. Transformer coupled designs tend to sound punchy and full bodied and offer
the added benefit of true electronic isolation. This greatly enhances their ability to interface with
other equipment with minimal noise or hum. There are many excellent preamplifiers on the
market today. Choose one that fits your budget and offers good performance, but remember that
you get what you pay for. If you have the opportunity to audition one or more preamplifiers
before you buy one, do so. Microphones and preamplifiers work together as a team and some are
just better matches than others.
The SF-24 is capable of substantial output signal, especially when used for high SPL applications
like drum overheads. It will not overload or produce distortion up to its SPL handling capacity of
130 dB SPL. In actuality, the SF-24’s ribbons would stretch well before its electronics would
reach an overload condition. Due to the high output potential of the SF-24, it is recommended
that the microphone preamplifier you pair it with have a switchable pad to prevent the possibility
of overloading the preamplifier’s input stage electronics. Some preamplifiers are more
thoughtfully designed than others, with a suitable pad that is placed before the preamp’s active
electronics, not incorporated into a “feedback loop” as is sometimes found. The latter design
could still produce distortion due to overloading even if the pad were used. Although this is
rarely an issue, we felt that it was important to cover the subject.
In conclusion, preamplifier coloration is optional and a matter of personal taste. Some people
love the effect of coloration while others strive for absolute transparency.
Stereo Microphones and Ground Loops
Some preamplifiers are prone to developing ground loops when used in conjunction with stereo
microphones such as the SF-24. Ground loops can develop in the preamplifier with any stereo
microphone regardless of type (i.e. condenser, dynamic, ribbon). A ground loop manifests itself
as unwanted buzz or hum at 60 Hz and/or harmonics of 60 Hz.
The condition is brought on when the left and right transducer elements are plugged into two
inputs of a stereo or multi-channel preamplifier. The two three-pin male XLR connectors of the
stereo microphone cable usually share Pin-1 as ground, so they are grounded to each other
through the cable set. If the grounding scheme within the preamplifier is poorly designed, or the
distances to internal ground are too great, a ground loop develops.
You can perform a simple test to check for this condition (preferably done with a pair of
headphones to avoid feedback). Plug one side of the stereo microphone into either preamplifier
input. Listen to the output of the preamp. All should be quiet except for the mic signal. Now plug
the second side into the next preamplifier input. If a noise or buzz develops, you have a ground
loop. The ground loop may be very slight or more pronounced, depending on the preamp.
Battery powered preamps usually do not exhibit this problem, and neither do well designed, lineoperated mic preamps. The simple fix is to disconnect one of the microphone’s two Pin-1 ground
connections. A better method is to make a small ground-lift adapter fashioned from a malefemale XLR barrel adapter. Switchcraft makes a very nice one and it takes less than five minutes
to wire it up. Simply connect Pin-2 to Pin-2, Pin-3 to Pin-3, and leave Pin-1 disconnected.
Correcting the problem at the preamplifier is preferable, but is often more difficult and/or
Equalization and Ribbon Microphones
One of the great strengths of ribbon microphones is how well they take EQ. Even with
substantial amounts of equalization, ribbons retain their natural, “real” quality. For example,
when a lead vocal is being performed on a ribbon microphone, you can boost the upper-end
frequencies to the point where the ribbon mic emulates the performance curve of a condenser
mic with excellent results. This is not to say that a ribbon microphone can replace a quality
condenser mic, but the EQ friendliness inherent in ribbon microphones does allow for an
enormous amount of flexibility.
The reason that ribbon mics take EQ so well is their inherent low self-noise, unusually smooth
frequency response characteristics and freedom from off-axis coloration. Dialing in high
amounts of equalization on condenser or dynamic microphones also means dialing in extra
amounts of the microphone's distortion products and self noise contributing to an unnatural,
unpleasant sound. Because distortion and self-noise are almost nonexistent in ribbon
microphones, high levels of EQ can be used without adding harshness or excessive noise.
Hum, Noise and Mic Orientation
All dynamic microphones, including ribbons, are susceptible to picking up stray alternating
magnetic fields. Power transformers (such as those found in guitar amplifiers) and alternating
current motors are the most likely sources of hum. In-wall wiring and electrical utility
transformers are other likely sources. A well-designed microphone provides shielding to
minimize the effects of such stray magnetic radiation. In some cases complete isolation is
impossible and the result is usually hum or buzz. Unpowered ribbon microphones can manifest
this condition to a greater degree because of their higher gain requirements. With vintage ribbon
microphones that often employ large, bulky magnet structures and are often poorly shielded, the
problem can be worse.
The SF-24 reduces this condition because the essential gain is provided at the microphone,
negating the need for additional gain to be supplied by the preamplifier. In addition, the Royer
SF-1, SF-12 and SF-24 family of microphones are designed to minimize the effects of unwanted
radiation by integrating the transducer barrel as part of the magnetic return circuit. Royer’s SFseries ribbon microphones go one step further by incorporating toroidal impedance matching
transformers, which have a natural ability to repel magnetic radiation.
Unwanted noise (hum) can only come from external sources. Fortunately, simply repositioning a
ribbon microphone is the best way to get rid of unwanted noise. If hum is detected, the
microphone is in the proximity of an alternating magnetic field.
While listening (preferably with headphones) to the mic, move it around. The mic will “find” the
noise source quite easily. For example, if you are miking a guitar amplifier and suspect the
amplifier’s power transformer may be the source of unwanted hum, move the mic around the
amp. You will probably find that the hum is louder as you approach the amplifier’s power supply
and quieter when you move it away. Eliminating the hum can be fairly simple and requires
finding the “null” point of the hum. The “null” point is the position that places the microphone’s
magnetic components away from the lines of the noise's radiation. Slightly rotating the
microphone is usually all that is required to cancel out the hum. This is similar to the procedure
guitarists use to eliminate hum from single coil guitar pickups: turning around slowly while
listening for the hum. There will be a position where the hum disappears completely.
Hum and other noise is often picked up in microphone cables. Since the output of Royer Active
Series mics is 15 to 25 dB higher than with traditional ribbon microphones, any noise picked up
in the mic cables will be at a corresponding lower level, and hence less likely to be
Microphone Techniques
General Tips for Using the Royer SF-24
The following are good basic starting places for recording with the SF-24. These positions are
known to produce good results, but experimentation is the key to getting the most out of your
recordings! Photographs of many of the following techniques can be found on our website
It is important to remember that the SF-24’s ribbon elements can be damaged by wind. When the
SF-24 is mounted on a boom stand, be sure the stand is moved slowly. When the microphone is
taken down, put it in its box immediately or, if it is to remain in its shock mount, place the mic
sock over the ribbon end of the microphone. Leaving the microphone out unprotected is inviting
a re-ribbon.
Ensemble Performances
The SF-24 records ensemble performances beautifully. Simply find the point in the room where
you hear the best blend of the instruments and room sound and place the microphone there, with
its logo facing the performers.
For stereo recordings of stringed instruments, start by positioning the microphone a few feet off
the body of the instrument. Depending on the acoustics of the room, you may want to move the
microphone closer to or further from the instrument to add or minimize ambience. For violin,
position the SF-24 horizontally, two or more feet above the instrument. For larger string sections,
try placing the microphone slightly above the instrumentalists and angled down; a distance of
three or four feet will do the job nicely.
Drum Overhead & Room
Position the SF-24 horizontally over the center point of the kit, two to three feet above the
cymbals. For a centered snare drum, aim the Royer logo at the snare. Adjusting the height of the
SF-24 by even 6-inch increments will produce dramatic variations in how the cymbals sit with
the rest of the kit. Many times an overhead SF-24 is all that is
needed for tom-toms and cymbals.
For a single point stereo room mic, position the SF-24
vertically at four to eight feet in front of the kit. Compress to
taste for either a very natural drum sound (light compression)
or large rock drum sound (heavy compression).
For jazz recordings, EQ is generally not required. For more
aggressive drum tracks where cymbals need to sizzle, you can
brighten them by adding a few dB of 10 K to 12 K.
Brass records beautifully with ribbon microphones. For an
overall picture of a brass section within a larger recording
session, try placing the microphone two to three feet above the instrumentalists and angled down,
at a distance of three to eight feet from the section. For a solo brass section, position the SF-24
vertically at a height of four to eight feet and anywhere from five to 20 or more feet from the
Close miking brass is a job for the Royer R-121 or R-122 - we do not recommend close-miking
with the SF-24.
Reed Instruments
Normal working distances are about a foot or two from a solo reed instrument. For multiple
instruments, try placing the microphone slightly above the instrumentalists and angled down, at a
distance of two to four feet.
There are several positions that will give excellent results with the piano. Start with a distance of
one foot to several feet from the knee of the piano. A more direct “up front” sound will be
achieved when the microphone is placed closer to the soundboard. If it is possible to remove the
piano lid, an SF-24 suspended horizontally over the soundboard will give outstanding results. If
the room sounds good, try positioning the mic 10 to 20 feet from the piano.
If you position the SF-24 somewhere between the soundboard and the open lid of the piano,
there will be some amount of reflected sound from the lid. Careful positioning can minimize or
accent lid reflections, depending on what sound you’re striving for.
Choir and Orchestra
An SF-24 can produce dramatically good recordings of an orchestra or choir. If possible, position
the SF-24 at a height of ten feet or so and a few feet behind the conductor. The wide stereo
pickup will reproduce the orchestra or choir with a stunning you-are-there realism. The rear lobes
of the figure-8 elements bring the ambient qualities of the recording environment into the
recording, adding to the natural feel of the recorded performance.
The SF-24 records percussion instruments naturally, without upper frequency hype or low-end
boominess. Congas, bongos and the like can be recorded with left/right stereo effect by
positioning the mic within a few feet of the instruments. Shakers, bells, triangles and other
instruments that are often problematic in the upper frequencies will record naturally and nonabrasively.
Vocal with Acoustic Guitar
For recording a vocal with acoustic guitar, two separate mono
tracks are required with little leakage between the tracks. One stand
and one SF-24 can do the job nicely when the two axes of
sensitivity are correctly oriented (see illustration).
The SF-24 is not recommended for close-miking loud amplified
instruments. Its sensitive ribbon elements were not designed for
extremely high SPL applications like close-miked electric guitar.
For close-miking high SPL sound sources, ruggedness is a must
and we recommend using our R-121 or R-122 ribbon microphones.
Specialized Stereo Recording Techniques
Classic Blumlein Technique
For many years, “coincident” microphone setups have been widely used for picking up sounds in
stereo as naturally as possible. The “Blumlein” technique, named for A.D. Blumlein, involves the
use of two figure-eight microphones positioned as in
the sketch (see Figure 1); so that one faces left and
the other faces right, at an angle of 90 degrees (i.e.,
each displaced 45 degrees from center).
Each microphone ultimately feeds one speaker in a
stereo system, and due to the directionality of the
microphones, the result is a very well defined stereo
image on playback. For classical music, particularly,
the reproduction can be very satisfying.
Figure 1
The SF-24 stereo microphone is two identical ribbon
microphones in just this Blumlein orientation: if the
microphone is placed in front of the performance,
with the Royer logo facing the center of the ensemble
to be recorded, the microphone will give a stereo
recording as per the Blumlein technique. Because of
the togetherness of the SF-24’s ribbon transducers,
sound will arrive at both ribbon elements at the same time. This means that the two channels can
be summed to mono with no comb filter effects, and room reverberation (undesirable in mono) is
cancelled to a surprising degree.
For the sake of clarity, engineers commonly refer to similar stereo miking with cardioid mics as
“X-Y.” When figure-8’s are used, it is more commonly referred to as “Blumlein” recording.
Mid-Side (M-S) Technique
In the early days of stereo radio broadcasting, the Mid-Side recording technique was developed
to allow for 1) simultaneous stereo and mono feeds from the same mic array and 2) electronic
manipulation of the width of the stereo image. In M-S recording, one mic faces sideways, one
faces forward as shown in Figure 2, and they are connected as shown in Figure 3.
With the SF-24's logo facing the center of the
performance, the mic is positioned for X-Y
recording. Rotating the SF-24 counter-clockwise by
45¼ positions it for M-S recording.
By inserting your SF-24 with the logo in the left slot
of the RSM-24 shock mount (see Using the RSM-24
Shock Mount, page 9), then facing the shock mounts
logo directly at the center of the performance, the
microphone will be rotated 45 degrees counterclockwise and correctly positioned for M-S
recording. With the SF-24 in a vertical position,
Figure 2
cable end down, the upper ribbon element faces the
center of the performance and is the “mid”
microphone, and the lower ribbon element is at 90
degrees to the performance and is the “side”
microphone. If the microphone is to be mounted
upside down, make the proper adjustments in your wiring orientation.
If the outputs of the mid and side elements are made equal using gain controls, the stereo pickup
will be similar to that of two microphones placed as a Blumlein X-Y pair, delivering a wide
stereo image. As you reduce the level of the “side” element, the width of the stereo image will
narrow until, with the side element turned all the way down, you have just the “mid” element
panned center and giving a mono pickup.
If the outputs of the “mid” and “side” elements are recorded on separate tracks, the electrical
connections shown in Figure 3 can be made at the mixer outputs and the adjustment of the stereo
separation can be done during mixdown, rather than during the actual recording.
Space does not permit a fuller discussion of the M-S intensity stereo format, first described by
Alan D. Blumlein over 50 years ago. We suggest the following reading on the subject:
W. Dooley & R. Streicher
“M-S Stereo: A Powerful Technique for Working in Stereo”
Audio Eng. Soc., Vol. 30 pp.707 (1982 Oct.)
Figure 3
Care and Maintenance
The SF-24 is a solidly built, precision instrument. All that is required to ensure proper operation
of this microphone is to follow some commonsense rules.
1. To avoid transducer damage, do not expose the microphone to severe shock or vibration. If
the microphone is accidentally dropped, test it to see if damage has occurred before returning
it to service. Low output or a dull sound would indicate a stretched ribbon.
2. Do not expose the microphone to direct blasts of air or strong air currents. Use a windscreen
or suitable blast filter when close miking a vocalist or certain types of wind instruments. Ppopping does not necessarily damage the ribbon element but may produce unacceptable
preamplifier overload and could cause damage to speaker systems.
3. Do not expose the microphone to liquids or caustic smoke.
4. Do not expose the microphone to strong alternating electromagnetic fields, i.e. the power
transformers in amplifiers, or a hum may result.
5. Use a soft cloth to clean the microphone body. A small amount of denatured alcohol can be
used to remove fingerprints and other stains.
6. Keep metal filings away from the microphone at all times. The SF-24's powerful magnets can
attract minute ferris particles into the ribbon transducers, compromising the performance.
7. When not in use, store the microphone in its protective carrying case. If the microphone is to
remain set up on a mic stand between sessions, cover it with its mic sock (provided with your
8. Leave disassembly of the microphone to a trained technician. There are no user-serviceable
parts inside.
Care for the Optical Black Finish
The SF-24's optical black finish is a sophisticated surface treatment designed to refract light
rather than reflect it. This makes the microphone appear less conspicuous, especially when used
with high intensity lighting or within a camera shot. The finish requires occasional maintenance
to retain a smooth, even appearance and to maintain its unique optical qualities.
The SF24's body is comprised of a low carbon steel alloy. Its finish consists of black chrome
deposited over a nickel substrate, creating a finish that minimizes the reflective nature of the
metal surface. A small amount of oil has been worked into the finish at the factory to protect it.
Over time, some of this oil will be drawn out due to "wicking" action; the physical handling of
the microphone, absorbent materials it is exposed to (like the foam padding of the microphone
case), etc. As the oils are drawn out of the microscopic surface layer, the microphone finish may
develop an uneven appearance. If this happens, simply massage the microphone gently with a
lint free cloth treated with a few drops of light machine oil or WD-40 (apply the oil to the cloth,
not to the microphone). Be very careful whenever working around the transducers to avoid
contamination of the ribbon elements. Following this simple procedure will protect the finish and
renew it to its original luster.
Due to the transducer’s powerful magnets, keep recorded tapes, spring-wound watches and
personal credit cards with magnetic coding away from the microphone to prevent possible
Excellent stereo imaging and separation in one microphone
Smooth, wide frequency response
Active electronics offer greatly enhanced output and a constant, optimized impedance to the
ribbon element
X-Y, M-S or mono recording from one microphone
Extremely low residual noise
Ribbon elements are unaffected by heat or humidity
Absence of high-frequency phase distortion
Excellent phase linearity – even off axis
Equal sensitivity from front or back of microphone
Consistent frequency response regardless of distance
Compact size
Acoustic Operating Principle:
Electro-dynamic pressure gradient with active electronics
Polar Pattern:
Symmetrical Figure-8
Generating Elements:
Two 1.8-micron aluminum ribbons
Frequency Response:
30 Hz – 15,000 Hz ± 3 dB
>-38 dBv Ref 1 v/pa
Self Noise:
<18 dB
Output Impedance:
300 Ohms @ 1 kHz
Recommended Load Impedance: > 1500 Ohms
Maximum SPL:
> 130 dB
Output Connector:
Male XLR 5 pin
Power Requirements:
48-Volt Phantom (per channel) only
Supply Current:
4 mA per channel
270 mm X 39 mm (base) X 25 mm (top) (10 5/8" X 1.5"
wide (base) X 1" wide (top))
531 grams (18.7 ounces)
Optical Black Chrome 18K Gold (optional)
Protective carrying case, protective mic sock, 25’ shielded
5-conductor cable with 5-pin connectors, adapter cable
terminating in two (2) XLR 3-pin male connectors, RSM-24
shock mount
Optional Accessories:
WS-12 blast filter, 10 dB in-line pads
To learn more about Royer products and their usage, visit our website at
Wiring Diagram
Polar Pattern
Frequency Response
Royer Labs hereby warrants all Royer SF-series microphones with the following terms and conditions.
Body fit and finish
Transducer frames/magnets
Vacuum Tube
Cables & Cable Sets
Shock Mount Accessories
Ribbon Element
10 years Parts and Labor
2 years Parts and Labor
2 years Parts and Labor
1 year Parts and Labor
From the date of original purchase and for the respective periods specified above, Royer Labs agrees to
repair, at its sole expense, all Royer Labs products which are defective in material and workmanship.
This warranty does not cover the following:
Defects or damage caused by accident, fire, flood, lightning or other acts of nature.
Defects or damage caused by abuse, misuse, negligence or failure to observe the instructions
contained in the owner’s manual furnished at the time of original purchase.
Damage caused during shipping or handling.
Products that have had their serial numbers altered or removed.
Products purchased in “AS-IS” (used) condition.
Products that have been altered or repaired by anyone other than a factory authorized service station.
2711 Empire Ave.
Burbank, California 91504
Telephone 818.847.0121
Fax 818.847.0122