Audio Engineering Associates AEA R44 User manual

AEA R44 and A440
Owner’s Manual
one of the quietest mics on the market and the quietest ribbon microphone ever. The 7 mA version has
a 9 dBA noise floor and handles 136 db SPL. The custom 9 mA version has a 6 dbA noise floor and
handles 132.5 db SPL. The A440 can drive very long mic cables without signal loss.
It’s Only a Microphone. Why Do I Need an Owner’s Manual?
Your new ribbon microphone, like all of the equipment in your recording system, is an investment in
your future. It also may be the most sensitive and delicate item in your studio. Knowing how to use it
properly will enable you to maintain its performance and value for decades to come — long after most
of your other equipment has become obsolete.
Your Microphone Needs Good Support.
By now, you have discovered that this is a large, rather heavy microphone. In fact, it is more than 12
inches long and weighs about 8 pounds. In order to support it safely, you need a strong and sturdy mi-
crophone stand, such as the Atlas MS20 or MS25. If you want to use a boom arm, you could add an
Atlas PB21X or better yet, use the Atlas SB36 studio boom stand. While there are many suitable stands
from other manufacturers, conventional “musicians’ series” folding tripod-based microphone stands are
not recommended because they are not robust enough to support this microphone safely. If you do need
a portable stand for your mic, check out the Modular Microphone Stands page at the AEA website:
http://www.ribbonmics.com/aea/modular_microphone_stands.html.
The AEA model R44 and A440 ribbon microphones carry forward the classic
tradition of the venerable 1930s RCA-44 into the 21st century. AEA’s range
of Big Ribbon™ mics offer the same warm, rich “long ribbon” sound of their
ancestors. The R44 series even uses “new old-stock” RCA ribbon material
and features a re-engineered output transformer that recaptures the sonic
signature of the original RCA-44 and surpasses it in frequency response and
dynamics. The R44C is a visual and sonic reproduction, taking the best of the
RCA-44B and BX design, while the R44CX is the high-output version.
The A440 marries the high-output CX motor to a phantom-powered discrete-
JFET impedance buffer with a very high turns-ratio transformer. The result is
Audio Engineering
Associates
1029 N. Allen Ave. Pasadena CA 91104 www.ribbonmics.com Phone: [phone] Fax: [phone]

Phantom Power: Friend or Foe?
The AEA R44, like most ribbon microphones, neither needs nor wants phantom power. (More about
the A440 Active Studio Ribbon Microphone in the next paragraph.) What will happen if you connect
this microphone to a phantom-powered input? In a perfect world, nothing will go wrong, and the mi-
crophone will work just fine. However, if there is any defect in the integrity of the microphone cable or
connection, or if the phantom power is not properly balanced, this could produce a voltage differential
across the output of the microphone which can cause the ribbon to stretch or snap. The best prevention
against this type of damage is to be certain that the phantom power has been turned off for at least two
minutes before you connect your microphone. This will allow time for any stored voltage to drain from
the blocking capacitors inside the mixing console.
The AEA A440, on the other hand, has internal electronics to amplify the signal and provide more
output. This circuit requires conventional P48 phantom power (48 VDC, 9mA) to operate. Although a
defective cable or unbalanced phantom power also can cause this microphone to perform poorly, just as
they would with any condenser microphone, these will not damage the ribbon of the microphone.
Environmental Hazards
The ribbon is a thin strip of aluminum foil, 59.7 mm long, 4.7 mm wide, and 1.8-microns thick. It is
tensioned lightly so that it can respond to even the most delicate high-frequency soundwaves, yet be
able to withstand a sustained sound pressure level of more than 130 dB. What can damage the ribbon,
however, is a strong gust of air, such as from a nearby open door, window, or air conditioning vent, the
close pulse from a bass drum, the turn-on thump from a guitar or bass amplifier, moving or carrying the
mic unprotected swiftly through the studio, or someone blowing into it to test if it is working.
While it is unlikely that such a blast of air will break the ribbon, it certainly can cause it to stretch.
When this happens, the performance of the microphone will be degraded until the ribbon is replaced.
When it is in use, avoid any situation where volumes of moving air can blow directly into the micro-
phone. To prevent wind from damaging the ribbon, keep the mic covered with a plastic or cloth bag
when it is not in use.
Covering the mic will prevent it from attracting “tramp iron” from the environment into the magnet
structure. These tiny filaments of metal are all around us, resting on most flat surfaces. The strong
magnetic field inside a ribbon microphone can draw these through the grille and into the gap where the
ribbon is located. Eventually, enough of them can build-up to form whiskers in the gap that will rub
against the ribbon, causing distortion and crackling noises. Bagging the mic whenever it is not being
used will keep these out.
Gravity also can have its effects. The ribbon in your microphone is supported at its ends, but is free
over its 2+ inch length. If stored horizontally over a very long period of time, the ribbon might sag due
to its own weight. Microphone ribbons have no inherent life cycle. Good ribbon elements that are over
30 years old are not uncommon. The custom case provided with your new microphone provides proper
support for the microphone when in storage or transit, and keeps it in the recommended vertical orien-
tation.

Getting the Most Out of the Bidirectional Pattern
As described earlier, pressure-gradient microphones are inherently bidirectional, with equal sensitivity
to the front and back of the diaphragm. In a well designed mic, the only difference is the absolute po-
larity of the signal. (ref. Figure-1A)
1Several paragraphs and diagrams in this manual have been adapted from: The Bidirectional Microphone: A Forgotten
Patriarch – by Ron Streicher and Wes Dooley; Journal of the Audio Engineering Society, Vol. 51, No. 4, pp. 211-225, 2003
April. A complete copy can be downloaded from the AEA website: www.ribbonmics.com.
Because the polar response of a pressure-gradient microphone obeys a cosine-law, the sensitivity
decreases evenly as the soundsource moves away from the primary 0° (or 180°) axis, until it reaches
90° (or 270°) where the microphone has a very steep null. (ref. Figure-1B) This is the deepest null of
all polar patterns — nearly -90dB in the plane of the diaphragm — with a well designed model. It is
important to realize that this null plane extends both laterally and vertically with respect to the princi-
pal axis of pickup.
Most people, when using a directional microphone, just aim it at the subject, giving little thought to the
overall polar response pattern. While this “point and shoot” approach might work in a simple recording
or PA situation, there is much more to consider when “the going gets rough.”
Careful aiming of the “nulls” of a microphone’s pattern often can be more critical to the quality of the
sound pickup than where the principal axis is pointing. Intrusive sounds, such as PA, monitor, rein-
forcement speakers, other nearby instruments, noisy air conditioning equipment, or other environmen-
tal noises, can be reduced significantly by proper aiming of the nulls of the microphone. By reducing
these unwanted sounds, the clarity of the pickup will increase dramatically. Your new AEA ribbon
microphone has a very deep null plane. Use it wisely and to your advantage.

Minimizing Feedback
Deep nulls mean good rejection of unwanted sounds. This can be most beneficial in sound reinforce-
ment situations, where feedback is always threatening.
Figure-2 shows a typical concert setup, where a performer is downstage-front and a central loudspeaker
cluster is directly overhead. In this situation, the loudspeaker cluster will be 90° off-axis (vertically) to
the microphone. Because a cardioid microphone is only -6dB down at 90° the potential for feedback
can be high. By using a bidirectional microphone, however, with the deep null plane aimed directly at
the cluster, the potential for feedback can be eliminated almost completely. With the performer directly
on-axis, the rear lobe will be aimed out into the audience, which is so much farther away that the in-
verse square law will prevent their pickup by the microphone.
Similarly, if side-fill stage monitors are used, because these also are at ±90° to the performer, a bidirec-
tional microphone again will provide optimum rejection of these for the prevention of feedback.

Reducing Environmental Noise
Out of doors or in large interior spaces such as soundstages, factories, or warehouses, environmental or
general background noise tends to approach a microphone along the plane of the horizon if its source
is either reasonably distant or random in nature. Because this soundwave will, in effect, produce equal
pressure on both sides of the diaphragm of a vertically-oriented bidirectional microphone (i.e. the
diaphragm is horizontal) this noise will self-cancel and sound sources that are closer and more directly
on-axis will prevail. Jim Tannenbaum, a very active film dialog mixer in Hollywood, explained at an
AES Workshop how he uses this to good effect in recording actors in a noisy environment: By placing
a bidirectional microphone just below the camera’s view and orienting its pattern vertically, the actor’s
voice is picked-up by the front lobe while the rear lobe is aimed at his feet — which presumably are
not making any noise at all. (ref. Figure-3) The result is that the environmental noise pickup is signifi-
cantly less than the direct sound of the talent, producing clean and useable dialog.

Minimizing Pickup of Nearby Instruments
A significant and ever-present problem in contemporary studio recording is minimizing leakage from
nearby instruments into the various microphones. While gobos (portable isolation walls) can be ef-
fective in isolating performers from each other, they often introduce their own set of problems. To be
effective, gobos are usually very bulky and occupy valuable floor space. They also inhibit the ability
of the musicians to hear each other, thus requiring complex and often cumbersome headphone monitor
mixes for the musicians.
One solution to this problem is to use bidirectional microphones and arrange the musicians so that they
are at right-angles to each other, thus placing nearby musicians in the null of their neighbor’s micro-
phone, and vice versa. Although this won’t entirely eliminate the need for gobos, it will reduce the
number you need. As a result, the studio can be less crowded, and because the musicians now will be
better able to hear each other directly, the need for numerous monitor headphones also can be reduced.
Another common problem in both recording and sound reinforcement situations occurs when a singer
is also playing an instrument, such as guitar or piano. The need to provide good isolation between the
singer’s voice and the instrument usually leads to the use of separate microphones for each, but this can
lead to problems of balance and phase interference between the microphones. In both of these situa-
tions, the use of a single bidirectional microphone can provide the solution.
Vocal ensembles, such as duets, trios, and quartets, also can use these microphones to good advantage
by grouping around the mic and balancing their voices to achieve a proper natural blend. This can elim-
inate the need to rely on a mixing engineer to make them sound right: the musicians do it themselves!
For Announcers, Dialog, and Radio Plays
Ever since the “golden days of radio” in the 1930s and ‘40s actors have appreciated working with bi-
directional microphones such as the RCA-44. Not only does this have an unsurpassed quality with the
human voice, the two-sided pickup helped to create the art of radio acting because it allowed the actors
to work on either side of the microphone so they were able to face and act to and with each other. Com-
ing into a scene meant doing little more than starting with one’s head turned slightly away from the
mic and then turning back toward the mic as dialog began. If a more distant approach was required,
beginning the scene just a step or two back and then moving towards the mic would produce this effect.
Coming in from an even greater distance could be accomplished by starting the dialog from the side
of the microphone and then moving around to be on-axis. Throughout all of this, the script could be
held directly to the side of the microphone allowing the actors to read, yet minimizing the sound of the
pages rustling as they were changed.
Proximity Effect
Proximity effect or “bass tip-up” is a characteristic of all directional microphones, but none exhibits
more than the single-diaphragm velocity microphone. In fact, it is the pressure-gradient component in
all directional microphones that renders them susceptible to proximity effect. Pressure response micro-
phones, on the other hand, are not subject to it and retain relatively flat low frequency response at any
distance.
Although this is generally considered the result of working at a very close distance to the microphone,
the AEA R44 and A440 exhibit measurable proximity effect at distances closer than six feet. (ref. Fig-
ure-4) This rising low-frequency response at closer working distances can be used to good effect, par-

ticularly with male voices to give them an almost “superhuman” richness and depth. Like most things
in audio, however, the potential tradeoff is reduced articulation or clarity that can result from excessive
bass response or “boominess.” Proximity effect should be treated like any other form of equalization
and, as such, used with care and moderation.

THE AEA R44 BIG RIBBON™ MICROPHONE
Design Concept:
The AEA R44 is an exacting reproduction of the original RCA-44B/BX velocity microphone originally
produced in the mid-1930s. After producing replacement parts and repairing these venerable classics
for more than a decade, AEA decided to reissue a new version of the microphone — one that would be
as close as possible to the original in every respect.
After consulting with many engineers, it was decided that the earlier versions, built from the late 1930s
to the mid-1940s, were the ones most prized by both users and collectors alike. Under the guidance
of a few of the engineers retired from the RCA production team, AEA began to build painstakingly
accurate, hand-assembled reproductions. Other than the magnets, even the parts of the AEA R44C and
R44CX are interchangeable with the original RCA microphones. The only caveat was magnet technol-
ogy. AEA microphones utilize Neodymium instead of Alnico magnets to provide increased output. The
R44CX is about 5 dB “hotter” than an original RCA-44 and the AEA R44C.
Features:
The R44 design runs contrary to all current ribbon microphone manufacturing. It is large and heavy
while other microphones are smaller and lighter. The internal ribbon element is by far the longest, and
its resonance tuning the lowest of today’s ribbon microphones. Because the ribbon is tuned to a very
low resonant frequency, it exhibits none of the upper midrange high-Q resonance peaks common to
large diaphragm condensers. This ribbon design delivers extremely fast and accurate transients. Such a
lightly-tensioned, ultra low mass ribbon is almost perfectly damped by the air itself. This approach had
been out of production for over 50 years despite remaining in continuous studio use. It is different, and
its sound is unique.
Characteristics of these microphones are their “warm” and “rich” sound when used to pickup vocals. It
is easy to hear why the original RCA44 was the microphone of choice for most of the singers through-
out the “golden age” of the big bands: Bing Crosby, Frank Sinatra, Ella Fitzgerald, Billy Holliday, and
many others. Similarly, instrumentals benefit from the “ribbon sound” that put Glenn Miller, Benny
Goodman, Tommy Dorsey, Harry James, Stan Kenton, and so many others on the air.
The single ribbon diaphragm provides an almost perfect figure-of-eight polar pattern, with even and
accurate frequency response as the sound source approaches from off-axis. The null at ±90° is almost
-90dB down relative to the front or rear of the microphone, providing it excellent rejection of unwanted
environmental noise.
The Big RibbonTM design provides very low self-noise and enables the microphone to handle high
SPL with wide dynamic range — maximum 140 dB/SPL above 200 Hz.
Because the AEA R44C and R44CX microphones neither need nor want phantom power, they can be
used with any high-gain, low-noise preamplifier. Check out the AEA TRP and RP48Q on the AEA
website: www.ribbonmics.com.

Specifications:
Operating Principle: Velocity microphone
Frequency Response: 20 Hz to 20 kHz
Maximum SPL: 165 + dB SPL above 1 kHz for 1% third
harmonic
Output Sensitivity: 2.25 mV / Pa into unloaded circuit
Output Impedance: 270 Ω broadband
Recommended Load: 1.2 kΩ or greater
Powering: Not required or recommended
Polarity: Pin 2 high for positive pressure on the front of the
microphone.
Connector: XLR-3M wired to a 3 meter captive cable
Off Axis Response:
Polar Pattern: Native bi-directional pattern
Horizontal: Level changes with angle, frequency
response is consistent, –90 dB null at 90° / 270°
Vertical: Level changes with angle, reduced HF
response above and below 0° / 180° axis, null at 90° / 270°
Transducer element
Ribbon Thickness: 1.8 µ (0.0000018 m) of pure
aluminum
Ribbon Width: 4.7 mm
Ribbon Length: 59.7 mm
Accessories:
Included: Custom storage / shipping case, stand adapter,
manual
Optional: Any length cable, inquire for price and delivery.
Custom transformer case laser engraved with your art or
logo
Limited Warranty:
Three years parts and labor, shipping not included.
Displayed range from 100 Hz up due to measurement room size limitations.
Weight: 7 pounds, 9 ounces in storage case
Length: 12.25 inches, Width: 4.62, Depth: 3.25”

THE AEA A440 ACTIVE STUDIO MICROPHONE
Design Concept:
The AEA A440 is based on the model R44CX Big Ribbon™ microphone, but uses a transformer with
a higher turns ratio and adds an internal phantom powered JFET low noise buffer amplifier. These in-
crease the output level by 20 dB and reduce the self-noise, making the A440 ideally suited for the most
critical recording applications.
Features:
The A440 shares many features and sonic qualities of its non-powered cousins, but has a character of
its own. It is often described as being more “open and transparent” than any other ribbon microphone.
With a high sensitivity of -33.5 dBV/Pascal and a low output impedance of 92 Ohms, it can be used
where other ribbon mics cannot — anywhere that low-noise, high immunity to RF or EMI noise fields,
and/or long cable runs are required.
The A440 is one of the quietest mics around and is the quietest ribbon microphone. At 7 mA current
draw, it has a 9 dBA noise floor and handles 136 db SPL. A custom 9 mA version has a 6 dbA noise
floor and handles 132.5 db SPL. Such wide dynamic range is equal to the best studio condenser mics.
Specifications:
Operating Principle: Velocity microphone
 Frequency Response: 20 Hz to 20 kHz
 Maximum SPL: 136 dB SPL with a 1 kΩload for < 1% THD
 Output Sensitivity: 30 mV (-33.5 dBV)/Pa, 1 Pa = 94 dB SPL
 Output Impedance: 92 Ωbroadband
 Recommended Load: 1 kΩor greater
 Powering: P48 phantom power, 7 mA
 Polarity: Pin 2 high for positive pressure on the front of the microphone.
 Connector: XLR-3M wired to a 3 meter Accusound cable
Off Axis Response: (level changes with angle, frequency response is consistent)
 Polar Pattern: Native figure-eight bi-directional pattern
 Horizontal: Level changes with angle, frequency response is consistent, null at right angles to major
axis 90°/270°
 Vertical: Level changes with angle, reduced HF response above and below 0°/180° axis, null at
right angles to major axis 90°/270°
Transducer element
 Ribbon Thickness: 1.8 µ (0.0000018 m) of pure aluminum
 Ribbon Width: 4.7 mm
 Ribbon Length: 59.7 mm

Displayed range from 100 Hz up due to measurement room size limitations.

WARRANTY
Audio Engineering Associates warrants the AEA R44C, R44CX, and A440 against defects in materials
or workmanship for three (3) years from the date of purchase. Ribbons damaged by phantom power or
excessive air turbulence are not covered by the warranty. For repairs to units exhibiting ribbon damage,
abnormal physical abuse, or that are out-of-warranty, AEA will provide a repair estimate and will not
proceed with service without the customer’s authorization. Shipping and insurance costs both ways are
the responsibility of the customer. Please contact AEA prior to sending the unit in for repair. A form for
requesting service may be found at www.ribbonmics.com.
No user serviceable or adjustable parts inside. Do not open the case.
Audio Engineering Associates
1029 North Allen Avenue, Pasadena, CA 91104
Phone: [phone] Fax: [phone]
URL: www.ribbonmics.com e-mail: [email protected]
References and Recommended Reading:
BASIC STEREO MICROPHONE PERSPECTIVES - A REVIEW, first published in the AES
Journal, vol. 33, no. 7/8, pp. 548-586, 1985 July/August; republished in the STEREOPHONIC
TECHNIQUES ANTHOLOGY, pp. 297-305
THE BIDIRECTIONAL MICROPHONE: A FORGOTTEN PATRIARCH, was first presented at
the 113th AES Convention in Los Angeles, 2002 October, Preprint no. 5646; it is scheduled for
publication in the AES Journal in the 2003 April issue (vol. 51, no. 4)
THE NEW STEREO SOUNDBOOK, third edition, by Ron Streicher and F. Alton Everest, published
by Audio Engineering Associates, 1998; www.stereosoundbook.com.
RIBBON MICROPHONE ESSAYS by Wes Dooley, Ron Streicher and Philip Merrill published by
Audio Engineering Associates, June 2003; www.wesdooley.com.

Appendix 1
1. THE PHYSICS OF RIBBON PRESSURE-GRADIENT MICROPHONES
All microphones respond to the minute changes in air pressure as a soundwave arrives at their dia-
phragm. As transducers, they convert this acoustical energy into electrical energy that can be amplified
and recorded or broadcast. Some microphones respond only to variations in the absolute pressure —
the compressions and rarefactions that travel through the air as a soundwave — as they arrive the sur-
face of the diaphragm. These are called pressure-response pickups and have an omnidirectional polar
pattern because absolute pressure is not dependent on the direction of approach. (ref. Figure-5)
The first microphones were developed by the infant telephone industry in the late 19th Century. These
were intended for close-talking and were omnidirectional because there was little need for a more di-
rectional polar response pattern.
The Physics of the Bidirectional Microphone:
With the rapid growth of the broadcast and talking-picture industries in the 1920s and early 1930s, mi-
crophones were needed that could be kept out of the camera’s view yet discriminate against extraneous
studio or environmental sounds and favor the talent that was in front of and more distant from them.

The first directional microphones responded to the difference in pressure between the front and back
of the diaphragm as the soundwave passed by. These were termed pressure-gradient microphones
and exhibited a figure-of-eight polar pattern. The diaphragm in these early microphones was a very
thin aluminum ribbon that was exposed on both sides; as the soundwave moved past it created a very
slight but nonetheless distinct difference in the air pressure on either side of the ribbon. This ribbon
was suspended in a magnetic field and thus generated a small electric current in direct response to its
movement. (ref. Figures 6A and 6B) The term velocity microphone also is commonly applied to ribbon
microphones because the current in the ribbon is directly proportional to the velocity of its motion in
the magnetic field.
Because these were dipoles, if a soundwave approached the diaphragm directly from either the front
or back, the ribbon would move equally. The only difference was the absolute polarity of the electrical
output: sounds arriving from the back produce polarity opposite to those arriving from the front. (ref.
Figure 7A and 7B)

The significant operational difference between the bidirectional and omnidirectional microphone is that
while the omni responds with equal sensitivity to sounds arriving from any and all directions, with a
properly designed single-diaphragm bidirectional microphone, a response null of almost -90dB will oc-
cur at precisely ±90° from the principal pickup axis. Figure-8 shows that this null exists both vertically
and horizontally because a soundwave approaching the microphone along the plane of the diaphragm
will produce equal pressure on both sides of the diaphragm. If there is no difference in pressure on the

While many other polar patterns are available from condenser microphones, and even some ribbons, it
is this bidirectional pickup that brought the classic RCA-44s early fame and kept them in the forefront
of the recording, broadcast, and motion picture industries from their introduction in the 1930s until
today.
Since the early 1980s, Audio Engineering Associates has been proud to spearhead the reintroduction of
these venerable classics to the industry, and to continue their tradition with new and improved models.
Visit www.ribbonmics.com for a full list of all of the models and accessories available.
front and back of the diaphragm, there will be no output signal. Because this null plane affects both
sides of the diaphragm equally, the “figure-of-eight” polar response will be uniform with respect to
frequency.

Appendix 2
Evolution of an Icon
1932 RCA-44A to the 2008 AEA A-440
The oldest piece of pro audio equipment still in regular use is the RCA 44. A revolutionary microphone
design, it became the standard of reference for live sound, broadcast, film sound, and recording. It was
developed when audio tests were difficult and critical listening was crucial to the process. More than
70 years later, the 44B and BXs are still first rank microphones used daily in music, voice, broadcast
and cinema applications.
Dr. Harry Olson is credited as the inventor of the ribbon microphone. He adapted the concept of the
ribbon loudspeaker, invented in 1924 by Erwin Gerlach, by reversing the transduction process. He
realized one could use a conductive ribbon lightly suspended in a transverse magnetic field, as either
a speaker or a microphone. That insight led him to develop of the first high-performance directional
microphone in the world, the bi-directional 44A.
The 1932 RCA model 44A was Olson’s first commercial success. “Two major characteristics of this
type of microphone are particularly attractive from the standpoint of high fidelity sound reproduction,
namely a uniform response frequency characteristic over the entire audio frequency range and a uni-
form directivity pattern over the entire audio frequency range. The ribbon-type velocity microphone
was the first wide-frequency-range and high-quality microphone which exhibited a uniform directivity
pattern over the entire audio frequency range.” (Olson, Journal of the Audio Engineering Society, June
1970)
The rapid advancement of permanent magnet technology in the 1930s had freed Olson’s ribbon micro-
phones from the constraints of using an electromagnet. The 44 had an accurate full-bandwidth figure-
eight pattern, a transparent wide-range sound, excellent dynamics, required no external power, and was
immune to humidity. These characteristics made the audio engineer’s job much easier, and set a stan-
dard to which others aspired.
The 44A was soon joined by the 77A, the first cardioid microphone. The 44A was replaced in 1936 by
the 44B which had more output and a gorgeous black and silver Art Deco case. The 1938 BX revision
kept the 44B’s high-output, double Alnico magnet design, but had a less reflective umber finish suitable
for the newly emerging medium of television. The 44BX remained in production until the mid 1950s.
In the mid 1970s RCA ceased all microphone production. However both the 44B and BX and its cous-
ins the RCA-77D and DX remain in continuous use in recording studios and on scoring stages.
As magnetic tape became the dominant media for recording, ribbon microphones fell out of favor.
Magnetic recording with its greater linearity and dynamic range solved many disc and optical re-
cording problems and pioneers such as Les Paul and the Beatles became quite creative with multi-
generational magnetic recording. However there was always a slight loss of highs from generation to
generation. Large capsule condenser microphones helped resolve this problem as they have a number
of high-Q resonances in the 8 to 12 K Hz range. The treble ‘tizz’ this imparts became popular, because
after a couple of transfers these recordings sounded just right on the radio or juke box.

With the advent of digital recording, ribbon microphones made a major comeback. Their ability to
record fast transients accurately without adding upper-range resonances became a positive attribute, as
high-frequency transfer loss was no longer a problem. Users have also become more familiar with the
usefulness of a ribbon microphone’s native figure-eight polar pattern and proximity effect bass tip-up.
With fundamental tunings as low as 16 Hz the 44 is the king of bass. The 44 is flat down to 20 Hz from
a distance, and if used closer than six feet starts to have bass tip-up. No wonder announcers love them.
AEA began restoring and repairing RCA ribbon microphones soon after RCA ceased production and
service. In the early 1980s AEA also began servicing and importing STC/Coles 4038 studio ribbon
microphones. Over the next two decades AEA started making replacement RCA parts, and finally
developed a complete set of external parts for the 44 based on the classic RCA 44BX built in Camden,
NJ. During this period appreciation for the 44’s sonic character continued to grow. Antique and radio
collectors also admired them which decreased their availability and increased their price.
Mentored by Jon Sank, one of the last engineers who worked for the RCA microphone division, Wes
Dooley (AEA’s owner and chief engineer) began work on reproducing the interior parts. The 44 had
been produced in Camden, New Jersey; Hollywood, California; London, England; and Australia. While
repairing and analyzing these different versions, Wes and his team correlated which design elements
had the most “pleasing” sound quality for their owners. The AEA R-44C incorporated those design ele-
ments.
The primary difference between the AEA R-44C and the RCA-44B/BX is in the magnets. The RCA-
44B/BX used high-output Alnico magnets, the best available at the time. By the 1990s, neodymium
had replaced Alnico as the best material for this purpose, so it was used in the AES R44C. True to their
origins in providing repair services for these classic microphones, all of the assemblies of the AEA
microphone are directly interchangeable with the original RCA.
AEA’s service department was already fortunate to be using New-Old-Stock (NOS) ribbon mate-
rial from the 1970s that had been made for RCA. Once a custom microphone output transformer was
developed that matched the original RCA sonics, the culmination of this work was the introduction of
the AEA model R44C at the 1998 AES Convention in San Francisco. AEA has continued to make use
of modern technology to create new versions so as to bring this classic microphone closer to Olson’s
ideal: the best microphone possible for music and voice work.
The AEA R-44CNE was released in 2001 to celebrate the 100th anniversary of the NAMM (National
Association of Music Merchants, now named the International Music Products Association). As with
RCA 44s produced in England and Australia, the R44CNE has a simplified shell and cushion-mount
assembly. The internal parts are the same as the ‘museum quality” R44C series. By simplifying the
shell and cushion-mount this version sells at a lower price than the model R44C, the 1936 museum rep-
lica.
AEA developed the ‘X’ motor option using higher energy magnets to increase the output of the micro-
phone by 6 dB. This version was developed at the request of scoring mixers who needed a lower noise
floor, and did not need to match exactly the sound of original RCA 44s. This allowed “Lord of the
Rings” scoring engineer John Kurlander to mix his AEA R44 string pair almost as high in the mix as
his main Neumann M-50 tube microphones on the Decca Tree.

Detail changes continue to be made to the AEA 44 series as AEA gains more experience. The most dra-
matic technical revision was changing the internal wiring from the top of the ribbon to the transformer
input leads. Examination of the RCA 44 production from England revealed that their wiring scheme
reduced hum sensitivity by 20 dB without altering the sound. This wiring was immediately adopted for
all R44 microphones. More recently the yoke material casting on the R44C was changed from zinc to
bronze. The original RCA zinc yokes were found to fail when the plating wears through and the zinc
is exposed to moisture. More recently the R44C cushion-mount cable-clamps were changed from cast
zinc to machined brass.
Recalling Olson’s prediction that a well designed ribbon microphone might have the lowest self-noise
of any microphone type, AEA next focused its attention on lowering the noise and extending the linear-
ity of the ribbon microphone / microphone preamplifier interface. The 2005 AEA model TRP ribbon
microphone preamplifier was designed specifically to deliver high gain while reducing noise and in-
creasing linearity. This JFET design has a low noise floor, is DC coupled for wide bandwidth, and has
a no load, ultra-high input impedance design that delivers exceptional frequency response linearity and
better signal to noise with ribbon microphones.
Following on the widespread acclaim for the TRP, the next logical step was to incorporate similar
circuitry inside the microphone itself. The AEA model A-440 debuted at the NAB Show in April 2008.
Its internal phantom-powered JFET buffer amplifier is combined with a new, higher-ratio transformer
to provide 12 dB more gain than the ‘X’ motor alone. The equivalent acoustic self-noise of the combi-
nation is 9 dB (A) or less – making it among the quietest microphones made. Although the acoustic fre-
quency response of an A440 is the same as an R44CX, the sonic character is different. This character is
often described as “warmer” or “more tube-like.” and the bass is reported as having more weight.
Placing a buffer amplifier inside the A440 radically reduces the distance between the ribbon step-up
transformer and the first electronics stage. This decreases mic-line noise interference. It also buffers
the microphone preamp from possible low frequency EQ effects as a ribbon’s output impedance rises
at resonance. The A440’s audio-band output impedance is a constant 92 ohms for flatter low frequency
response when driving typical microphone preamps.
The trade off with such an active studio ribbon designs is a reduction of the 165 dB SPL capabilities
of the AEA’s passive R series ribbon microphones. While microphone positions that exceed 135 dB SP
are rare two examples are extremely close horn and percussion microphone positions pickup . Under
such circumstances, moving the microphone back three to six inches can solve the problem.
The A440 has the ability to drive a 1,000 ohm load at SPLs up to 135 dB and a high sensitivity of -33.5
dBV at 94 dB SPL (30 mV/Pa). The A440 matches conventional microphone preamplifiers quite well.
The A440 draws 7 mA of P48 phantom power. This amount of current allows it to achieve a noise floor
of 9 dB (A) or less with a headroom limit of 135 dB SPL.
Knowledgeable engineers never stopped using the 44. In the mid 1960s remote recording pioneer Wal-
ly Heider always used RCA ribbons on big bands and horn sections. Capitol Records Studios maintains
a large collection of 44s and has used them continuously on projects since the 1940s. Performers such
as Bing Crosby owned their own personal 44s. Young Frank Sinatra’s use of a 44 in live performances
was brilliant. He understood how to work the 44 to change his sound dynamically during a song and
increase its dramatic impact.

Contemporary scoring engineers also consistently use the 44. Scoring engineer Shawn Murphy typi-
cally records his string solos with a Blumlien pair of ribbons forward, and a pair Schoeps MK2H om-
nis further back.. Itzhak Perlman’s solos in “Memoirs of a Geshia” (2005) were recorded using AEA
R44Cs as the Blumlein pair. In 2005 EmmyLou Harris won a best female country vocal Grammy with
“The Connection” which Nashville producer/Engineer Brian Ahern recorded using a single an ‘X’ mo-
tor AEA R44. In 2008 The Turtle Island String Quartet album “A Love Supreme” won a Grammy for
Best Classical Crossover album. All the closer microphones were AEA ribbons, with the electric cello
on an AEA R44CNE. http://www.wesdooley.com/pdf/PR_Turtle_Island_String_Quartet2.doc
Is the A440 the best 44 incarnation ever? Time will tell. The A440 is a very useful development of the
44. Engineers who have considerable experience with both RCA and AEA 44s like it very much. On
Hollywood scoring stages and at world class studio facilities such as Blackbird in Nashville it is being
used on major projects. The 44 is an astonishingly good microphone which is why AEA started repro-
ducing it in 1998. It has been evolving for over 75 years, and has adapted amazingly well to contempo-
rary studio needs. There is likely a lot more that will happen in this ongoing story, and AEA is honored
to be part of it. Your ears get to decide.