Selectable diaphragm condenser microphone

Selectable diaphragm condenser microphone
US 20080152174Al
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2008/0152174 A1
Marshall
(54)
(43) Pub. Date:
SELECTABLE DIAPHRAGM CONDENSER
(52)
Jun. 26, 2008
US. Cl. ...................................................... .. 381/172
MICROPHONE
(76) Inventor:
Leonard Marshall, El Segundo,
(57)
CA (U S)
A condenser microphone having a capsule With a cardioid
pattern diaphragm on opposite sides of a back plate Wherein
COrreSpOndenCe AddreSSI
WELSH & FLAXMAN LLC
2000 DUKE STREET, SUITE 100
ALEXANDRIA, VA 22314
(21) APP1- NOJ
each diaphragm is selectively activated via a sWitch to com
plete the audio circuit. The microphone employs tWo different
diaphragm materials to produce tWo different sound repro
duction characteristics. A ?rst diaphragm produces a “Warm
and lush” sound output, While the second diaphragm pro
11/641,948
duces a “bright and airy” sound output. The microphone
Dec‘ 20’ 2006
behind the grill indicating Which capsule diaphragm is acti
_
includes the use of a pair of light emitting diodes located
(22) Flled:
_
_
_
_
Pubhcatlon Classl?catlon
(51)
ABSTRACT
Int, Cl,
H04R 19/04
(200601)
vated. The dual diaphragm arrangement is mounted on a
standard microphone body and includes conventional elec
tronics for connection to an associated piece of audio equip
ment producing phantom poWer.
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Patent Application Publication
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Patent Application Publication
Jun. 26, 2008 Sheet 2 0f 4
US 2008/0152174 A1
Patent Application Publication
Jun. 26, 2008 Sheet 3 0f 4
US 2008/0152174 A1
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Patent Application Publication
Jun. 26, 2008 Sheet 4 0f 4
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US 2008/0152174 A1
5:25
US 2008/0152174 A1
Jun. 26, 2008
SELECTABLE DIAPHRAGM CONDENSER
MICROPHONE
[0012] 3) Bidirectional, Which picks up sound from tWo
opposite directions.
BACKGROUND OF THE INVENTION
describe the response of a microphone to sound sources from
1. Field of the Invention
The present invention relates to sound producing
various directions. Each type of polar pattern has its oWn
[0013]
[0001]
[0002]
In other Words, the term polar pattern is used to
place and usage in the recording process. Generally, micro
microphones and more particularly to a condenser micro
phones tend to become more directional in focus as frequen
phone formed With tWo different sound producing dia
phragms on opposite sides of a back plate, Which are operable
independently to produce different sound reproduction char
cies increase. In other Words, diaphragms are generally less
sensitive to high frequencies off axis. The cardioid is the most
common polar pattern found in microphones. Cardioids pick
up sound primarily from the front of the diaphragm. The back
acteristics.
[0003]
2. Description of the PriorArt
of the diaphragm rejects sound, alloWing the engineer to
[0004]
It is often desired that an audio system produce a
isolate the signal source from other performance elements or
background noise. Omni is used to capture room ambience
and re?ections along With the source, thereby yielding a more
open sound compared to the more focused quality of cardioid.
Wide variety of sounds depending upon the particular material
being played, the location of the sound system and/or the
mood desired by the listeners. Most often, these types of
changes in audio output are generated and regulated by
adjustments to the ampli?er audio settings of the base and
Omni is desirable for vocal groups, Foley sound effects, and
realistic acoustic instruments. Omni also exhibits signi?
treble circuits, in addition to adjusting the volume control.
[0005] In the recording process, the diaphragms of the
cantly less proximity effect than cardioids.
microphones generate the original sound. Diaphragms of dif
may be used, of the same or different materials, hoWever, all
diaphragms are polariZed and operate at the same time to
ferent materials, conductive coatings, thicknesses or stiff
nesses have a marked effect on the character of the sound that
is ultimately heard by the listener. Recording engineers select
a particular microphone to enhance, or make more pleasing to
the listener the voice or instrument being recorded.
[0006] In a condenser microphone, the capsule includes a
diaphragm spaced from a back plate. The diaphragm acts as
[0014] In multi-pattem microphones, plural diaphragms
create the multi-pattem.
[0015] With the foregoing in mind, a need exists for an
improved condenser microphone providing the user With the
added versatility of tWo different sounding cardiod pattern
microphones in one. The present invention provides such a
microphone.
one plate of a capacitor and the diaphragm vibrates When
struck by sound Waves, changing the distance betWeen the
tWo plates and therefore changing the capacitance. Speci?
cally, When the plates are closer together, capacitance
increases and a charge current occurs. When the plates are
further apart, capacitance decreases and a discharge current
occurs. A voltage is required across the capacitor for this to
Work. This voltage is supplied either by a battery in the
microphone or by external phantom poWer source from the
equipment to Which the microphone is connected.
[0007] Since the plates are biased With a ?xed charge (@Q,
the voltage maintained across the capacitor plates changes
With the vibrations in the air, according to the capacitance
equation:
QICXV Where
QIcharge
in coulombs,
CIcapacitance in farads and Vrpotential difference in volts.
The capacitance of the plates is inversely proportional to the
distance betWeen them for a parallel-plate capacitor.
[0008] Condenser microphones produce high quality audio
signals and are a popular choice in laboratory and studio
recordings and range in co st from inexpensive to very expen
sive. Condenser microphones are available With tWo capsules
Wherein the signals from each are electrically connected to
provide a range of polar patterns. Polar patterns are a graphi
cal representation of the microphone’s directionality.
[0009]
Every microphone has a property knoWn as direc
tionality. This describes the microphone’s sensitivity to sound
from various directions. Some microphones pick up sound
equally from all directions, While others pick up sound only
from one direction or a particular combination of directions.
The types of directionality are divided into three main cat
egories:
[0010]
l) Omnidirectional, Which picks up sound evenly
from all directions.
[0011]
2) Unidirectional, Which picks up sound pre
dominantly from one direction and includes cardioid,
i.e., heart shaped patterns.
SUMMARY OF THE INVENTION
[0016] The present invention is a condenser microphone
having a capsule With a cardioid pattern diaphragm on oppo
site sides of a back plate Wherein each diaphragm is selec
tively activated via a sWitch to complete the audio circuit. The
microphone employs tWo different diaphragm materials to
produce tWo different sound reproduction characteristics. A
?rst diaphragm produces a “Warm and lush” sound output,
While the second diaphragm produces a “bright and airy”
sound output. The user selects the particular diaphragm via a
sWitch mounted on the microphone body such that the polar
iZing voltage running through the back plate is active on only
the diaphragm selected. The microphone includes the use of a
pair of light emitting diodes located behind the grill indicat
ing Which capsule diaphragm is activated. The dual dia
phragm arrangement is mounted on a standard microphone
body and includes conventional electronics for connection to
an associated piece of audio equipment producing phantom
poWer.
[0017] It is an object of the invention to provide a backplate
formed of tWo pieces screWed together in a back-to-back
con?guration or formed of one integral piece With dia
phragms on both sides Wherein the back plate is polariZed
during operation.
[0018]
Another object is the provision of a microphone
Wherein one diaphragm is formed from a thicker material than
the other diaphragm.
[0019] Still another object is to provide a microphone
Wherein the indicator lights are LEDs located behind the grill
and re?ect upon the diaphragms.
[0020] Still further it is an object to locate the LEDs in close
proximity to a respective diaphragm in order to provide heat
thereto and aid in controlling moisture on the diaphragm.
US 2008/0152174 A1
Jun. 26, 2008
[0021] Still another object is the provision of a microphone
having different sounding outputs controlled by a sWitch
output. Thus, the user Will knoW Which side of the micro
phone 10 to face depending on the sound quality desired When
mounted on the microphone body to activate one diaphragm
or the other independently.
operating.
[0022] Another object is the provision of a microphone
capable of providing a visual indication of the type of sound
With a suitable bracket 22 and support post 21 extending from
the top closure 15. A rubber isolation grommet 23 acousti
output produced by the microphone and Which diaphragm of
the microphone is activated, thus indicating to the user Which
side of the microphone to orate into.
cally isolates the capsule assembly 20 from the metal parts of
the microphone 10.
[0032] The capsule assembly 20 includes an integral back
[0023]
plate 27 or a pair of back plate sides 27a, 27b screWed
Other objects and advantages of the present inven
tion Will become apparent from the folloWing detailed
description When vieWed in conjunction With the accompa
nying draWings, Which set forth certain embodiments of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a front perspective vieW of the “Warm” side
of a microphone in accordance With the present invention.
[0025] FIG. 2 is a rear vieW of FIG. 1 shoWing the “bright”
side of the microphone in accordance With the present inven
tion.
[0026] FIG. 3 is a sectional vieW of FIG. 2 With the micro
[0031]
The capsule assembly 20 is mounted to the body 12
together in a back-to-back relation to form a common back
plate, a ?rst cardioid pattern diaphragm 24 and a second
cardioid pattern diaphragm 26 mounted on opposite sides of
the back plate 27. The capsule components are secured
together via screWs 29 to form the capsule assembly 20. The
back plate 27 is generally made from a metal such as brass and
is about 0.5 inches thick When side 2711 is screWed to side 2711.
The ?rst and second diaphragms 24, 26 are made from mate
rials having different re?ective properties. The second dia
phragm 26 on one side of the capsule assembly 20 is designed
from a thin material to provide a lush Warm or bassy sound,
Whereas the ?rst diaphragm 24 is designed from a thicker
material to provide a bright and airy sound. Since thick mate
phone rotated 90 degrees.
rials do not move as easily as thin materials When subjected to
[0027] FIG. 4 is a schematic draWing of the sWitching cir
cuit of the microphone.
[0028] FIG. 5 is a top perspective vieW With the grill
removed.
acoustic Waves they produce different sounds. Thicker mate
rials have a brighter sound because the loW frequencies roll
DESCRIPTION OF THE PREFERRED
EMBODIMENTS
[0029] The detailed embodiment of the present invention is
disclosed herein. It should be understood, hoWever, that the
off sooner than they do on a thinner material While high
frequencies shoW a rising response at a certain point in the
upper midrange. The preferred diaphragm material is mylar.
[0033] In audio applications diaphragm materials betWeen
2-30 microns can be used, but professional condenser micro
phones subjectively sound best betWeen 3-10 microns.
[0034]
The chart beloW shoWs differences in three different
mylar diaphragm materials:
disclosed embodiment is merely exemplary of the invention,
Which may be embodied in various forms. Therefore, the
details disclosed herein are not to be interpreted as limiting,
but merely as the basis for the claims and as a basis for
teaching one skilled in the art hoW to make and/or use the
invention.
[0030] Referring to the draWings, a condenser microphone
10 includes a cylindrical body 12 having a bottom ring 14 and
6 micron
8 micron
12 micron
50 HZ
100 HZ
lKhZ
3.5 kHz
—1 dB
—2 dB
—4 dB
0 dB
—1 dB
—2 dB
0 dB
0 dB
0 dB
+3 dB
+l dB
+2 dB
15 kHz
+3 dB
+1.5 dB
+l dB
a top closure 15 secured thereto. The body 12 can be made of
[0035]
various plastics, hoWever, metal is the preferred material. A
thin metal sheets like titanium. The plastic diaphragms are
coated With a loW resistance conductive coating such as gold,
female XLR cable connector 1 6 is mounted in the bottom ring
Diaphragm materials usually are polyester, mylar or
14 for attachment to a male XLR cable connector at the end of
a cable (not shoWn) going to an ampli?er, poWer source or
nickel or similar materials Well knoWn in the art. Any com
other audio equipment used to reproduce the sound. That is,
rials Will change the characteristics of the diaphragm reaction
the cable functions to connect the microphone 10 to an input
on an electronic sound system piece of equipment, such as a
to the incoming acoustical sound Waves. Even small differ
mixer, tape player, etc. A frame 18 connects the bottom ring
14 and top closure 15, and holds a printed circuit board PCB
good studio or home audio equipment.
[0036] The net effect of the tWo different diaphragm mate
(not shoWn). The PCB includes a circuit that connects to the
capsule assembly 20 on one side and the XLR output connec
tor 16 on the other side. The circuit functions to amplify or
rials mounted on opposite sides of a back plate 27 is that you
convert the voltage from the high impedance capsule signal to
a loWer impedance signal used in or compatible With profes
sional audio applications. The circuit board could also be put
under or on top of the top closure 15 in a smaller version of the
same microphone. A suitable grill 19 cooperates With top
closure 15 and covers the top of the microphone 10. The top
closure 15 includes indicia areas 13a, 13b thereon to indicate
Which side of the capsule assembly 20 is to be used for a Warm
sound output and Which is to be used for a bright sound
bination of plating and thickness of the plastic or metal mate
ences in the diaphragm structure or properties can be heard on
get tWo microphones With different sound reproduction char
acteristics in a single unit Which operate independently. Fur
ther, While being mounted in a back-to -back con?guration the
diaphragms do not interfere With each other When one is
active and the other is not. This is a result of the sound being
produced on only one side of the polariZed back plate 27 at a
time. Since the sWitch 30 only connects one diaphragm at a
time to the preampli?er no sound is produced on the opposite
side of back plate 27. That is, back plate 27 is alWays polar
iZed through the voltage running through the DC converter 52
and one diaphragm at a time is connected via sWitch 30 to
US 2008/0152174 A1
preampli?er 31. Preampli?er 31 is internal to the microphone
and ampli?es the received acoustic signal and sends the signal
out to a microphone input, shoWn as pins 1, 2, 3 in FIG. 4 on
a piece of audio equipment 55 from Which the voltage con
verter 52 receives its phantom poWer. The other diaphragm
has no connection to the preampli?er 31 at this point. There
fore, it strictly acts as the back of the capsule and does not
interfere With the front, thereby not affecting the cardioid
pattern of the other diaphragm.
[0037] The back plate 27 is connected to a resistor R6 at one
end and a capacitor C4 Which runs to ground G at its other
end. R6 is connected to the voltage converter 52 that increases
the voltage from the phantom poWer supply to that required
by the microphone 10. The voltage converter 52 draWs very
Jun. 26, 2008
moisture from accumulating on the diaphragm assembly 20.
Moisture is knoWn to cause unWanted noise. Lastly, the LED
When lit indicates What side of the microphone the user should
orate into.
[0041]
While the preferred embodiments have been shoWn
and described, it Will be understood that there is no intent to
limit the invention by such disclosure, but rather, is intended
to cover all modi?cations and alternate constructions falling
Within the spirit and scope of the invention as de?ned in the
appended claims.
1. A condenser microphone providing different sound
reproduction characteristics, comprising:
a body;
little current so it does not affect the voltages needed to run the
a capsule assembly extending from said body including a
other part of the circuit. The capsule itself does not draW any
current so it does not load doWn the output of the voltage
converter 52. As previously stated, the phantom poWer is
obtained from the audio equipment to Which microphone 10
material having different re?ective properties than the
back plate With a ?rst side and a second opposite side
With a cardioid pattern diaphragm on each side thereof,
Wherein the diaphragm on the ?rst side is made from a
diaphragm on the second side; and
is connected via a XLR cable connection.
[0038]
PoWering a microphone via phantom poWer is Well
knoWn in the art and the circuit diagram in FIG. 4 is just one
example of hoW a condenser microphone obtains its poWer, as
such those skilled in the art Would appreciate that a variety of
circuits could be used. U.S. Pat. No. 4,757,545, Which is
incorporated herein by reference, shoWs yet another phantom
poWer supply for a condenser microphone.
[0039] Leads 28a, 28b are connected to a double pole,
double throW sWitch 30 that is used to activate either the ?rst
diaphragm 24 or the second diaphragm 26 in accordance With
the selected sWitch position, such that When lead 28a is acti
vated, the second diaphragm 26 Will be operative and send
signals to preampli?er 31, and When lead 28b is activated the
?rst diaphragm 24 Will be operative and send signals to
preampli?er 31. When the ?rst diaphragm 24 is activated by
sWitch 30 to complete the circuit a user can then hold the
“Bit” side near his/her mouth during use and the opposite
occurs When the second diaphragm 26 is activated. Thus, only
one side of the microphone 10 is used at a time. The circuit
diagram in FIG. 4 illustrates the double pole, double throW
sWitch 30 connected betWeen the diaphragms 24 and 26 and
a preampli?er 31, located on the circuit board to perform
a sWitch mounted to the body to selectively activate one of
said diaphragms independent of the other to produce a
microphone With tWo different sound reproduction char
acteristics.
2. The microphone of claim 1, Wherein backplate is formed
of tWo pieces screWed together in a back-to-back con?gura
tion.
3. The microphone of claim 1, Wherein backplate is formed
of one integral piece.
4. The microphone of claim 1, further including at least one
indicator light providing visual indication of Which dia
phragm is activated.
5. The microphone of claim 4, Wherein the at least one
indicator light is a plurality of light emitting diodes With one
of each of said light emitting diodes being associated With a
single diaphragm.
6. The microphone of claim 1, further including a grill
connected to the body for covering the capsule assembly.
7. The microphone of claim 1, Wherein one diaphragm is
thicker than the other.
8. The microphone of claim 4, Wherein the at least one
indicator light is located behind the grill and re?ects upon the
amplifying of the audio signal received from the activated
diaphragm.
diaphragm.
9. The microphone of claim 4, Wherein the at least one
indicator light is located in proximity to one of said dia
phragms and provides heat to aid in controlling moisture on
[0040] A pair of resistors R11, R12 and light emitting
diodes (LEDs) 32, 34 are mounted on opposite sides of the
dual diaphragm capsule assembly 20. The resistors function
to prevent the LEDs from receiving too much current. The
LEDs are electrically connected through the double pole,
double throW sWitch 30, Wherein one side of the sWitch 30a
controls Which diaphragm goes to the preampli?er 31 and the
other side of the sWitch 30b controls Which LED is energiZed.
The ?rst diaphragm 24 and LED 34 are connected on opposite
sides of the isolated sWitch 30 so they do not interfere With
each other. When a diaphragm 24, 26 is activated by the
sWitch 30, the associated LED 32, 34, respectively, is also
activated by sWitch 30 and Will be lit, providing a visual
indication of Which diaphragm 24, 26 is sWitched to an opera
tional mode. Each LED is positioned behind the grill 19 and
the diaphragm.
10. The microphone of claim 1, Wherein the back plate is
polariZed during operation.
11. A condenser microphone providing different sound
reproduction characteristics, comprising:
a body;
a capsule assembly extending from said body Wherein the
capsule includes a back plate With a ?rst side spaced
from a ?rst cardioid pattern diaphragm and a second side
spaced from a second cardioid pattern diaphragm of a
different thickness than the ?rst diaphragm; and
a sWitch mounted to the body to selectively activate one of
said diaphragms independent of the others to produce a
microphone With tWo different sound reproduction char
shines light on re?ecting surfaces of the diaphragms 24, 26,
providing a gloWing effect behind the grill 19, particularly in
loW ambient light conditions. Also, because of the position of
each LED 32, 34 behind the grill 19, and in proximity to the
formed of tWo pieces screWed together in a back-to-back
diaphragms 24, 26, heat is generated Which helps prevent
con?guration.
acteristics.
12. The microphone of claim 11, Wherein back plate is
US 2008/0152174 A1
13. The microphone of claim 11, wherein back plate is
formed of one integral piece.
14. The microphone of claim 11, further including at least
one indicator light providing visual indication of Which dia
phragm is activated.
15. The microphone of claim 14, Wherein the at least one
Jun. 26, 2008
17. The microphone of claim 14, Wherein the at least one
indicator light is located behind the grill and re?ects upon the
diaphragm.
18. The microphone of claim 14, Wherein the at least one
indicator light is located in proximity to one of said dia
phragms and provides heat to aid in controlling moisture on
the diaphragm.
19. The microphone of claim 1, Wherein the back plate is
indicator light is a plurality of light emitting diodes With one
of each of said light emitting diodes being associated With a
polariZed during operation.
single diaphragm.
are formed from different thickness of mylar.
16. The microphone of claim 11, further including a grill
connected to the body for covering the capsule assembly.
20. The microphone of claim 1, Wherein the diaphragms
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