AUDIO ENGINEERING ASSOCIATES
AUDIO ENGINEERING ASSOCIATES
1029 No. Allen Avenue, Pasadena, CA 91104
Phone: (626) 798-9128 / Fax: (626) 798-2378
E-mail: [email protected]
COLES 4038
STUDIO RIBBON MICROPHONE USERÕS GUIDE
By Ron Streicher and Wes Dooley
QUICK START
I F YOU CAN'T WAIT TO USE YOUR NEW COLES 4038, PLEASE READ THESE
PRECAUTIONS FIRST SO YOU DON'T ACCIDENTALLY TRASH YOUR NEW TOY.
1 . KEEP YOUR 4038 COVERED BY THE SUPPLIED PLASTIC BAG WHEN NOT
ACTUALLY BEING USED.
A. THIS KEEPS THE STRONG MAGNET INSIDE THE 4038 FROM ATTRACTING
"TRAMP" IRON PARTICLES WHICH POLLUTE THE INSIDE OF THE MIC.
B. THIS ALSO PROTECTS THE VERY THIN (.6 micron) AND FAST ALUMINUM
RIBBON INSIDE THE 4038 FROM BEING STRETCHED IF THE MIC CASE LID
SNAPS SHUT OR IF THE MIC'S STAND IS MOVED TOO QUICKLY ACROSS THE
STUDIO.
2 . NEVER PLUG THE 4038 INTO PHANTOM OR "T" POWERED MIC INPUTS.
"T" POWER WILL INSTANTLY DESTROY A RIBBON (AND ALSO CAN HURT A DYNAMIC
MIC). PHANTOM POWER CAN DO THE SAME IF YOU HAVE A BAD MIC CABLE. IT IS BEST
TO PLAY IT SAFE BY TURNING OFF THE MIC POWERING AND WAIT A MINUTE. AFTER
THIS IT IS SAFE TO PLUG IN YOUR RIBBON MIC. (THIS WILL ALLOW BOTH OF THE MIC
PREAMPS' INPUT CAPACITORS TO DISCHARGE FULLY AFTER YOU TURN POWERING OFF.)
3 . TO INSERT THE CONNECTOR, LINE UP THE PINS AND PUSH IT IN. TO REMOVE THE
CONNECTOR, SQUEEZE THE SILVER OVAL-SHAPED RING AT ITS WIDEST POINTS AND PULL
THE CONNECTOR STRAIGHT OUT.
4 . WHILE THE COLES 4038 CAN HANDLE VERY LOUD SOUNDS AT HIGHER
FREQUENCIES, IT CAN BE DAMAGED BY STRONG AIR GUSTS.
SO AVOID KICK
DRUMS AND LOUDSPEAKER BASS PORTS BECAUSE THEY CAN STRETCH EVEN A WELL
PROTECTED RIBBON. IF YOU CAN FEEL THE AIR MOVE, DON'T PLACE THE MIC THERE.
THE 4038 HAS A 1% DISTORTION POINT AT 110 Hz OF 125 DB SPL; AT 55 Hz THIS 1%
POINT DROPS TO 110 DB SPL. THUS LOUD HORN SECTIONS ARE NO PROBLEM, BUT ON
BASS GUITAR AMPS YOU SHOULD KEEP BACK TWO FEET OR MORE. ALSO REMIND THE
PLAYER TO TURN DOWN THE AMP BEFORE CHANGING GUITARS OR SPL AT! (JOE
CHICARELLI SUGGESTS THAT ON THE BIG MARSHALL STACKS, IT CAN BE USEFUL TO USE
A 6" POPPER STOPPER IN FRONT OF THE 4038 AND/OR SET IT AT AN ANGLE TO THE
SPEAKER.)
5 . WHEN USED AS A VOCAL MIC, USE A 6" POPPER STOPPER.
THIS HELPS PROTECT THE RIBBON FROM BREATH BLASTING, POPPING, AND MOISTURE.
Coles 4038 UserÕs Guide
November, 1997 ©
Page 1
A QUICK TOUR OF THE 4038
It has been said that the railroads built America in the nineteenth century.
These Òiron horsesÓ ran on Òribbons of steelÓ and carried commerce from one
end of the country to another. In their own way, some of the classic early
microphones also helped build America in the twentieth century. From their
iron horseshoe magnets and ribbons of aluminum, the sounds they produced
traversed the airwaves of the nation. These venerable microphones by such
companies as RCA and Western Electric brought us the guiding voices that
carried us through the ÒGreat Depression,Ó World War II, and the
entertainment that sustained us through these troubles during the ÒGolden
Age of RadioÓ in the 1930Õs and Õ40Õs.
Thus it comes as no surprise that when in the early 1950Õs the BBC wanted
a new microphone for FM broadcast which could continue in this tradition,
they chose the principle of the ribbon as the basis for their new design. The
proven quality of the ribbon was exemplified by its smooth frequency and
excellent transient response, and the ÒrichÓ quality it imparted to both voices
and music. However, the BBC also wanted an affordable microphone which
would better withstand the rigors of use and would be smaller than its
predecessors . The result was the Coles 4038 studio microphone.
SO HOW DOES THE COLES 4038 SOUND?
Very good indeed for a wide variety of users. In fact, the BBC / STC design
team intended the 4038 to become the principal studio microphone for the
BBC É and that it did. Functionally this means that, as with a classic Neve
console, nothing sounds bad on a 4038 and many things sound just glorious.
As with all mics, the choice of a preamp influences the final sound, although
it's hard to find a combination that actually sounds bad with the 4038. (Jim
Boyk, the artist in residence at California Institute of Technology has gone as
far as building a transformerless all tube mic preamp for his pair of 4038's.
He reports that he has yet to find 4038's resolution limit; the better he's
been able to tweak his mic preamp, the more he hears. As a concert pianist,
he records an instrument that is challenging to all microphones.)
W h a t o t h e r i n s t r u m e n t s s o u n d g o o d w i t h a 4 0 3 8 ? S a x players
(and recordists such as Keith Johnson of Reference Recordings) report that the
4038 is their mic of choice. LA area b rass player Malcolm McNab personally
owns several pairs of 4038's, as does the award-winning scoring mixer Shawn
Murphy, who has been using as many as ten 4038's at a time on the b r ass
sections down at the Sony Pictures Scoring Stage. A comment received from
Philadelphia was that the 4038 is the choice for sounds that are bigger than
life. D r u m s a n d a m p l i f i e d g u i t a r would fit that description. From way
down south in New Orleans came news about capturing the o r i g i n a l B e a t l e s
Coles 4038 UserÕs Guide
November, 1997 ©
Page 2
d r u m s o u n d with a good big room and a single 4038 with a tube preamp as
the overhead mic. From New York we received an update on that sound,
utilizing solid state mic preamps with a pair of 4038's for s t e r e o d r u m
overheads, a large diaphragm dynamic for the kick, and a large room to
record it in. Bob Rock recently used a pair of 4038's on Metallica as the air
mics on a Marshall stack of g u i t a r a m p s . Steve Albini uses the 4038 on
single g u i t a r a m p s at a distance of about two feet out.
Acoustic instruments in general seem record well with the 4038. When
one high end studio in LA got its first pair of 4038's the chief engineer
wondered what in the world they sounded like. He had a pair of Avalon mic
preamps available and an a c o u s t i c g u i t a r was what he first tried. He
became another immediate convert. V i o l i n virtuoso Itzhak Perlmann
recently completed a recording at for Telarc Digital, engineered by Jack
Renner, where a coincident pair of 4038's were the principal pickup.
Michael Bishop, also of Telarc Digital used the 4038's on sax and flute
the following week with very pleasing results. Doug Sax of The Mastering
Lab used them for a Sheffield direct to disk project to record a brass choir.
Voices record well too. One producer was having problems with a female
voice on a U47; they liked the midrange, but she was having sibilance
problems. Then they tried a 4038, and got exactly the sound they wanted.
If you have ever heard a southern gospel quartet and liked that deep,
deep sound on the bass voice, you'll want to try a 4038 close up while using a
6" popper stopper. Bi-directional ribbon mics are the king as far as
proximity-effect bass boost is concerned.
This space reserved for your contribution.
Coles 4038 UserÕs Guide
November, 1997 ©
Page 3
AN IN-DEPTH TOUR OF THE 4038
The 4038 has been in continuous production for over 40 years. That's way
longer than even the Shure SM58. As they say in the film business, ÒIts got
great legs.Ó What has given the 4038 such staying power? Audio quality,
reliability and versatility are the key elements. It's a classic that just never
went out of production. So let's start with a quick physical tour of the
microphone and then think about how to use it on a session.
Starting at the bottom, you'll notice that the Coles 4038 uses a different
output connector than you are used to. This is the original Western Electric
(as in AT&T's manufacturing division) Type-4069 microphone connector. For
vintage mic collectors this means there is still a source for this connector; for
you it means learning about a new one. If you took the 4069 apart you
would find that the three female sleeves are actually individual miniature
single-circuit patch bay jacks. This is definitely a legacy from the earlier
telephone era. Inserting the 4069 into the base of the microphone is fairly
easy: it just slides and snaps in. Releasing it again after use takes a
moment's reflection. Look for the silver band around the base of the mic.
Notice that a screw holds it in place and that it slightly bulges 90 degrees
either side of the screw? By squeezing this band on either side where it
bulges out, you'll lift the internal latch pin and then you can slide out the
connector. While this can be a careful two handed operation, it's easy to get
the hang of it. The BBC owned a number of microphones that employed the
4069 connector and they intended that the connector be permanently left on
a mic stand so that it functioned as a quick disconnect mic mounting system
somewhat like we use the Atlas LO-2 mic stand quick disconnect adapter.
The advantages of the BBC / Western Electric system is that it includes the
audio connection and locates the reflective surfaces as far away from the mic
element as possible. AEA offers a custom stand adaptor (4069 SA/XLR) for
the 4069 connector which provides American standard 5/8"-27 female
thread and is wired with a 16" cable and XLR-male connector. Alternatively,
the 4070 adaptor directly converts the output to a conventional XLR-male.
Up a bit from the silver connector release band, you will find a rotating
ring assembly with three eyelets that protrude around the circumference.
Two are opposite each other on the ring and the third is offset about 60
degrees. This mounting system is intended for flying or hanging the 4038.
The two eyelets opposite each other are for flying the mic in a concert hall or
large studio where the cables can come from opposite sides of the room. The
eyelets at zero and sixty degrees are intended for hanging the mic from a
large studio boom stand such as the Atlas BS 36W. The AEA 4038ES custom
elastic suspension mount uses all three of these eyelets to safely and securely
isolate the microphone from mechanical shock when boom mounted.
Coles 4038 UserÕs Guide
November, 1997 ©
Page 4
AEA also uses this rotating ring assembly for our multipurpose 4038SA
stand adapter. This mounts to the 180 degree eyelets using 10-32 Allen head
screws. The adapter itself accommodates both a 5/8"-27 mic stand and the
European style 3/8" mic stud. The European mic mounts are provided both
on the centerline and offset to one side to allow symmetrical stereo setups
when using our SMP series of stereo microphone positioners Ñ heavy duty
stereo bars specifically designed to securely handle the weight of the Coles
4038. The SMP will also support AKG, Neumann, or other large format
microphones Ñ in all standard coincident or near coincident arrays.
Next, above the rotating ring, you will find the 4038's yoke assembly. You
can use this to adjust the angle of the mic head relative to the connector
assembly. While the yoke provides a range of over a 90 degrees from the
vertical (it's normal side address mode) all the way to being in line with a mic
boom arm, because this is a bi-directional (figure eight) mic, it is generally
advisable to angle it to minimize the ÒplumbingÓ in the way of the rear pickup
lobe. The front (positive pressure lobe) of the 4038 is the side opposite the
yoke assembly. The yoke assembly mounts to the microphone head through
two short metal pads that penetrate the microphone's acoustical case. These
pads are epoxied directly to the magnet assembly. If the microphone is
dropped, these pads can be broken loose from the magnet. The good news is
that the mic is designed so that even if things start rattling around, the mic
does not fall apart. The bad news is that putting the whole thing back
together is tedious bench work and if the yoke's pivot rod has been bent, the
only way to fix it, is to replace it. Hint: Be careful and donÕt drop the mic!
The yoke supports the mic head which contains the 4038's motor
assembly and acoustical case. The unique shape of this acoustical casing was
carefully worked out for best high frequency response, both on and off the
centerline axis. The center top indentations on the front and rear grilles form
an acoustic lens for the ribbon behind it. There is a fine mesh protective
metal screen on the inside of the perforated metal outer case. Another fine
mesh metal screen is positioned only a tenth of an inch either side of the
ribbon to provide more mechanical protection and tame the low frequency
resonance peak. Finally, there are acoustical wings inside the 4038's case
that help extend the low frequency response down to 30 HZ while reducing
the mic's sensitivity to mechanical shock.
As with all bi-directional microphones, the principal pickup axes are
straight to the front and back. While the amplitude at the rear is the same as
the front, it is important to remember that the polarity is reversed. This is
equivalent to hitting the "phase switch" on a consoles input Ñ not something
we usually do without thinking about it. At right angles to the front/rear
Coles 4038 UserÕs Guide
November, 1997 ©
Page 5
main axis is the null plane. Think of it as a slice of silence. In this 90 degree
plane, a figure-8 mic just does not hear much at all. Remember, however,
that since the 4038 is a bi-directional microphone, the room tone it picks up
from the rear becomes an important part of the overall sound. Therefore,
using the 4038 in a room that you hate the sound of can be troublesome at
best, unless you use the "slice of silence" to tune most of the room out.
A LITTLE BIT OF THEORY
The operating principle of the ribbon microphone is actually quite simple.
A thin corrugated ribbon of aluminum foil (In the 4038's it's 0.6 microns
thick, less than the thickness of a human hair, by 0.23" wide and 1" long) is
suspended vertically between the north and south poles of a permanent
magnet. When sound waves strike this ribbon Ñ or diaphragm Ñ and set it
in motion, a small current is generated. This current is the electrical analog of
the sound wave. Thus, a ribbon microphone can be considered as a
motor/generator type of transducer, which converts one form of energy
(sound) into another form of energy (electricity). Like a Honda power
generator, it's just an electrical conductor being pushed through a magnetic
field. Completing the system, an internal transformer matches the ribbon's
very low output voltage and impedance (0.24 ohm for the 4038) to an
impedance and level appropriate for use with microphone preamplifiers.
Because the ribbon is fixed at both ends and very thin compared to its
width and height, it is only free to move fore-and-aft in response to the
presence of a sound wave. Thus, the ribbon responds to differences in air
pressure between its front and back surfaces. If the sound wave approaches
the microphone from directly along its principal axis Ñ perpendicular to the
plane of the ribbon Ñ this differential pressure on the ribbon will be at its
maximum and so will the microphone's electrical output. There are two such
maxima, directly to the front and directly to the rear of the ribbon. A well
designed bi-directional (figure-8) ribbon mic will have similar frequency
response on both the front or rear axis, only the polarity changes. (Keeping
polarity straight can be important with both microphones and loudspeakers.
When observing many sounds such as plucked strings, drums, brass, and
voices on a scope or DAW waveform display, you may see that the signal goes
positive higher above the zero line than negative below it (or vice versa).
These are asymmetrical waveforms. If you change the polarity (marked
phase on most consoles) of these signals, it tends to sound as if you made an
EQ change. However if you try to EQ back to the original sound, you never
can get it back. Thus it is a good idea to watch polarity in microphones,
cables, electronics and speakers.).
As the sound source moves from the central axis, the differential pressure
Coles 4038 UserÕs Guide
November, 1997 ©
Page 6
on the ribbon decreases, as will the electrical output. Thus it is easy to
understand why a well designed bi-directional microphone has almost no
output from sounds arriving from an angle of 90¡ off-axis: these sound
waves strike the ribbon edgewise and exert equal pressure on both the front
and rear surfaces of the diaphragm. The result is that there is no difference
in the pressure exerted on the two surfaces of the ribbon; hence there is no
motion, and no output signal is generated.
The term velocity or pressure gradient is often used when describing
ribbon microphones, because as noted above, as a sound wave passes the
ribbon, minute differences in air pressure are created between the front and
rear surfaces of this diaphragm. The classic ribbon microphones were the
first to have a directional pattern, what we call a figure-of-eight or bidirectional polar response pattern. Earlier microphones were
omnidirectional pressure microphones and responded only to the variations
in the absolute air pressure of a sound wave without any particular regard to
the sound's direction or distance of origin. Ribbon (velocity or pressure
gradient) microphones have a well defined figure-of-eight directional
pattern and their bass frequency response varies depending on whether the
sound source is near or far. A near source will sound bass heavy compared
with a far source. This bass boost proximity effect is characteristic of all
directional mics.
DESIGN OF THE COLES 4038 MICROPHONE
ÒThe BBC-Marconi Type A microphone, believed to be the first of this
type to be manufactured in Great Britain, was produced in 1934 É The
performance of this microphone is still good, even by modern
standards, but the instrument is bulky and there has long been a
demand É for a smaller version giving an equal or better performance.Ó
With these criteria as the goal, the engineering division of the BBC went
about designing a new microphone to meet the growing demands of their FM
radio and television production departments. The end result was the BBCÕs
model PGS bi-directional ribbon microphone. Size and weight reductions
were relatively easy to accomplish. But along the way, the additional
problems of extended frequency response, ribbon fragility, and susceptibility
to wind noise, were carefully addressed.
The commercial realization of this microphone is the Coles 4038. The 4038
is first mentioned in print in December of 1955 in the excellent BBC
monograph by D. E. L. Shorter and H. R. Harwood on the design of the PGS.
The 4038 has a smooth response from 30 Hz to above 15 KHz, exhibiting an
ideal 6 dB per octave roll-off at high frequencies. A symmetrical polar
response in the vertical direction was achieved through the unique shape of
the microphone housing which is designed to function as an acoustic lens. Its
Coles 4038 UserÕs Guide
November, 1997 ©
Page 7
standard electrical output impedance of 300 ohms remains nearly constant
throughout the audio passband. Special attention was paid to reducing hum
pickup through the use of a shielded toroidal output transformer and
starquad style wiring around the ribbon itself.
The 4038's ribbon diaphragm has a very low mass and high internal
damping, so transient response is exceptional. The ribbon is made of a special
beaten aluminum and is about one third the thickness of ribbons used in the
RCA 44s and 77s. The BBC PGS and STC 4038 design team developed a ribbon
corrugation pattern that did not quickly lose it's tension. In constructing the
4038, particular attention was given to special internal protection for the
ribbon which greatly reduces its susceptibility to damage from either
mechanical shock or excessive wind velocity Ñ problems to which earlier
ribbon microphones such as the RCA 44 were particularly vulnerable. The
practical benefit for 4038 users is that they rarely have to re-ribbon the mics
unless damaged by external forces.
ÒCARE and FEEDINGÓ of RIBBON MICROPHONES
Although the Coles 4038 has been designed to withstand the normal rigors
of the recording studio, as with any precision device certain precautions
should be taken when handling and using it. These notes apply to using any
ribbon microphone. The first (and this should be the most obvious but, alas,
is not) is that the microphoneÕs greatest enemy is a strong air current. It is
extremely foolish to blow into any ribbon microphone to test if it is working!
Not only does this present a very high wind stress to the diaphragm Ñ one
potentially strong enough to tear the ribbon from its mounting Ñ but it also
forces moisture and dust particles from the breath and/or air into the
microphone housing and onto the diaphragm. This defeats the two fine mesh
metal screens which protect the ribbon. If simply talking into it is not
sufficient, the safest way to test whether a microphone is working is to snap
your fingers in front of it or, if necessary, to gently scratch the microphone
grille with your finger nail.
Similarly, a ribbon microphone is best used only indoors, away from
strong air currents such as air conditioning vents or open windows. Rapid
movement of the microphone while unsheathed (panning on a studio boom or
even while carrying) should likewise be avoided. If the microphone must be
used where it will be subject to strong air currents, it should be protected
with an external windshield or screen. (In an emergency, even a clean sock
or handkerchief will suffice.) With vocalists we recommend the use of the
two layer 6" ÒPopper Stopper.Ó This provides good pop blast / breath
moisture protection and allows you to set a minimum working distance to
limit proximity bass boost. When not actually in use, a ribbon microphone
should be stored in a protective plastic or close weave cloth bag.
Coles 4038 UserÕs Guide
November, 1997 ©
Page 8
Second, and equally important, is to avoid any microphone powering.
Remember that a ribbon microphone is nothing more than a conductor
suspended in a magnetic field: when the conductor moves, it generates
current and vice versa, a current presented to the conductor will force it to
move. The voltage appearing on a badly wired microphone cable from a
ÒphantomÓ or other powering system can instantly rip the ribbon from its
mounting. This problem is not unique to ribbon microphones. Even rugged
dynamics such as Shure SM57s can be damaged by such exposure, even
through they might still produce sound. Such exposure also can magnetize
and permanently degrade the mic's output transformer.
With ÒphantomÓ or simplex powering schemes, the two conductors (pins 2
and 3) are supposed to be at the same voltage potential. However, should
there be any fault in the cable between the mixing console or power supply
and the microphone (such as a shorted or poorly soldered connection) this can
produce a voltage differential which then will be presented to the connector
of the microphone and back into the ribbon. One quick zap, and the ribbon
will be stretched or blown out of existence! "T" microphone power is even
more dangerous, since it inherently presents a differential of 12 volts
between pins 2 and 3. Therefore, before connecting a ribbon microphone, be
absolutely sure that the powering is turned OFF for this input channel. DonÕt
take chances: if you canÕt turn it off, itÕs best not to plug it in.
Even after you have actually turned off microphone powering, wait a
minute or two before you actually plug the mic in. Most modern microphone
preamps are transformerless and protect the preamp electronics with a pair
of large capacitors. These capacitors are energy storage devices, so it can take
a while for the voltage charge to dissipate. If you should happen to plug in a
mic when both of the capacitors are not equally discharged, you might lose or
stretch a ribbon, even through the powering has been turned Òoff.Ó
The 4038 is a sensitive studio microphone designed for voice and music
pickup. It is not intended for pickup of sound effects such as gunshots or
explosions, use in the wind or in situations where the low frequency SPL is
extremely high. Like most full range ribbon microphones the 4038 will
handle very high SPL at high frequencies and is displacement limited at low
frequencies. For example the 4038Õs 1% THD point at 110 Hz is 125 dB SPL
while further down at 55 Hz this 1% point is reduced to 110 dB SPL. For use
in high wind or outdoor situations there are specialty announcer microphones
such as the Coles 4104 which will withstand 20 to 25 mph wind streams.
There is also the old RCA BK5 podium voice mic which some claim with it's
rolled off bottom end was designed to survive the sound of a 45 caliber
automatic discharged from 5 feet. In the early 1960s, Electro Voice
introduced the robust model 664 dynamic mic. (Lou Burrough's was famous
for demonstrating that it could be used to pound nails and would then still
Coles 4038 UserÕs Guide
November, 1997 ©
Page 9
function as a microphone. Commented a studio microphone manufacturer
when asked how well their microphone would handle this treatment: ÒYou
buy my microphone, I'll buy you a hammer.Ó)
PRACTICE GOOD HOUSEKEEPING
Put your mics away in their cases when not in use, or cover them when
left out on stands. Keep your environment clean so as to protect mics in it
from being exposed to more dust, dirt, and smoke than absolutely necessary.
Microphones are expected to be able to respond to the very minute variations
in air motion or pressure which define a sound wave. They just don't do this
as well when encrusted with dust, dirt, or a mixture of smoke and hot, moist
breath. Studio microphones are designed to deliver original performance
levels for a long time under normal conditions. We suggest the the use of an
external breath filter (such as a nylon screen) for close vocals. Such a pop
filter sets a consistent working distance and limits the amount of proximity
bass boost. They are also easier to clean than the microphone's own internal
windscreen.
It is also critical that a dynamic (ribbon or otherwise) microphone never
be placed directly on any surface without wrapping it in a clean cloth or
plastic bag for protection. Dynamic microphones employ powerful magnets
and any loose iron dust will be attracted to the microphone. Minute iron dust
particles are a fact of life and exist everywhere; some are so micro-fine they
can pass directly through both the outer and inner screening and be drawn
directly inside, collecting in the magnet gap. When there is a sufficient buildup of foreign matter inside a microphone it restricts the diaphragm's free
movement and causes distortion.
If you leave your 4038 in the studio between sessions, cover it with the
supplied plastic bag when not in use. Even better, keep the microphone
safely stored in its original case and plastic bag. This will protect it from
wind and mechanical shock. Try to develop good ribbon habits such as
moving your mic only when it's in a protective plastic bag and always closing
its case gently. To a microphone, slamming the cover of the case is like like a
Òsmack upside the head.Ó It can hurt.
Coles 4038 UserÕs Guide
November, 1997 ©
Page 10
AEA and the COLES 4038 MICROPHONE
Since the early 1980s, Audio Engineering Associates has been importing
and promoting the Coles 4038 and its companion, the 4104 close-talking Òlip
ribbonÓ microphones. In this time, the 4038 has gained a wide reputation in
North America in all fields of recording and broadcast, from motion picture
scoring stages and announce booths to concert halls, and rock-and-roll
studios. Sheffield Labs, George Massenberg, and Steve Albini use them
regularly on their projects. Keith Johnson of Reference Recordings reports
that they are the only mics he owns that he has not felt the need to modify.
Scoring mixer Shawn Murphy owns a half-dozen and on occasion has added
another four for large brass dates. And the list is growing É
AEA supplies the Coles 4038 microphone system in a rugged foam-lined plastic
carrying case. Standard output impedance is 300-ohms. A 30-ohm version is
available as an option for use with 1000'+ cable runs or special mic preamps. The
standard output connector is the Western Electric type-4069. Four mounting options
are available:
1 . T h e 4 0 6 9 S A / X L R is a vertical hard-mount stand adaptor, attached to the
4069 connector assembly, through which we wire an 16 inch length of Mogami Òstar
quadÓ mic cable with a male Switchcraft XLR-type connector, pin 2 high. This
ÒstandardÓ option offers the optimum acoustical configuration for vertical stand
mounting and is a convenient one piece solution.
2 . A E A ' s 4 0 3 8 S A is a custom-machined hard-mount that bolts to the rotating
suspension ring for either vertical mounting to a 5/8"-27 stand or horizontal
mounting to a European 3/8"-16 mic stud. The horizontal mount is used with our
Stereo Microphone Positioner for vertical coincident setups, and features offset
mounting holes for proper alignment. With this setup, either a short, rigid 4069 to
male XLR-3 adaptor or the short XLR pigtail is used.
3 . T h e 4 0 3 8 E S is an elastic suspension mount that allows the microphone's angle
and rotation to be adjusted when hung from a boom. With this setup, either a
short, rigid 4069 to male XLR-3 adaptor or the short XLR pigtail is used.
4 . Overhead suspension in an auditorium or concert hall by using the built in
rotating suspension ring. This allows the 4038 to be oriented as needed. The short,
rigid 4069 to male XLR-3 adaptor is most appropriate for this situation.
Parts and accessories:
AEA maintains a stock of spare parts and accessories for the 4038, such as ribbons,
connectors, various types of stand adaptors, speciality shock and stereo mounts and
protective screens. We also do in-house replacement of ribbons.
AEA warrants the Coles 4038 to be free of defects in materials and
w o r k m a n s h i p f o r a p e r i o d o f o n e - y e a r f r o m d a t e o f p u r c h a s e . This
warranty is transferable but you must retain the original invoice for proof of purchase.
Contact us immediately if your mic has a problem. Repair or replacement is at our
option. Damage resulting from modification, unauthorized service, repair, or abuse is
not covered by this warranty. AEA shall be the sole determinant of what constitutes
Òabuse.Ó (Exposure to rough handling, wind, excessive low frequency SPL, moisture or
liquids, and microphone power such as phantom or "T" are some examples of abuse.)
Coles 4038 UserÕs Guide
November, 1997 ©
Page 11
SPECIFICATIONS of the COLES 4038
P o l a r r e s p o n s e : Bi-directional (cosine, figure-of-eight)
I m p e d a n c e : 300-ohm is standard; also 30-ohm by special order
F r e q u e n c y r e s p o n s e : 30 Hz to 15,000 Hz (see spec. sheet curve)
S e n s i t i v i t y :-65dB re: 1 Volt/dyne/cm2
D i s t o r t i o n : Inversely related to frequency. Like most ribbon
microphones the 4038 will handle very high SPL at
high frequencies and is displacement limited at low
frequencies. For example the 1% THD point at 110 Hz
is 125 dB SPL while further down at 55 Hz this 1%
point is reduced to 110 dB SPL.
C o n n e c t o r : Western Electric type 4069
Dimensions:197 mm x 83 mm x 61 mm; 7 1/4" x 3 1/4" x 2 3/8 "
Weight: 1.08 Kg; 2 lb. 6 oz.
F i n i s h : Black textured enamel over heavy gauge brass; grille
woven monel mesh
H u m r e j e c t i o n :Internal hum neutralizing balanced wiring coupled
with magnetic shielding of the toroidal ribbon-tomicrophone line transformer reduces response to stray
magnetic fields by 30 to 40 dB.
MATCHED PAIRS
Matched stereo pairs of 4038's are selected on an "as available" basis.
(The curves above: H2 and H4 are pulled from one such pair.)
Coles 4038 UserÕs Guide
November, 1997 ©
Page 12
AEA PRODUCTS
AEA manufactures a range of equipment that is complementary to the 4038.
The Stereo Microphone Positioner is a heavy duty multi-microphone
mounting system that allows pairs of heavier microphones such as the Coles
4038, AKG 414, and Neumann TLM-170 to be easily rigged in any semicoincident or coincident stereo perspective. The system is designed to be
stand mounted, boom mounted, or flown. Useful information about these
stereo perspectives can be found in our review paper on basic stereo
microphone perspectives cited at the end of this manual.
Other AEA products include recording and processing electronics: an MS
(Mid-Side) stereo line level dual matrix processor; a robust stereo headphone
beltpack amplifier that also incorporates a MS stereo decoder; and a
Stereophile "Recommended" stereo microphone preamplifier with dual mode
MS matrix and Jensen input and output transformers.
TELL US YOUR 4038 EXPERIENCES
As you've already discovered, we're personally involved with these
microphones and are interested in hearing about your experiences with them
as well. We welcome any specific discography information on recordings
you've made and would like to know how the mics were set up, processed,
and mixed. Any general comments about the 4038, accessories, and
operating manual, either positive or negative, are invited.
ADDITIONAL REFERENCES
1. Wes Dooley and Ron Streicher, ÒBasic Stereo Microphone Perspectives, A Review,Ó
July/August 1985 Journal of the Audio Engineering Society. This is a tutorial about the
basic stereo microphone techniques, who developed them, and comments about when
you might want to use them or avoid them.
2
F. Alton Everest and Ron Streicher ÒThe New Stereo Soundbook,Ó 1992 by TAB Books.
This is perhaps the best general review book available on the ins and outs (no pun
intended) of stereo recording and reproduction. It reflects on the effect of the acoustic
environment on both recording and playback perceptions. This book is the easiest to
read and most comprehensive introduction to stereo published. We try to keep
autographed copies in stock.
3. D. E. L. Shorter and H. D. Harwood, ÒMonograph No. 4, The Design of a Ribbon Type
Pressure-Gradient Microphone for Broadcast TransmissionÓ December 1955 published by
the British Broadcasting Corporation. This is the definitive treatment on the design of
the BBC PGS microphone, the prototype for the commercial 4038.
4. Michael Gayford editor, ÒMicrophone Engineering Handbook,Ó published 1994 by
Focal Press, Oxford, England. This is a serious reference book. Michael Gayford writes
an excellent chapter on Microphone Technique and Gunter Rosen from Beyer Dynamic
writes a chapter on Ribbon Microphones. A number of other subjects such as Standards,
Microphone amplifiers and transformers, Microphone testing and High-Quality RF
condenser (Sennheiser) microphones are covered.
Coles 4038 UserÕs Guide
November, 1997 ©
Page 13
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