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UNIDIRECTIONAL DYNAMIC MICROPHONE
222 HARTREY AVE
,
EVANSTON, IL, 60204 U.S.A.
AREA CODE 31 21866-2200
CABLE: SHUREMICRO
.M.IOTII..O--LI
-.-...-
TWX:
91 0-231 -0048 TELEX. 72-4381
MICROPHONES
AND
ELECTRONIC
COMPONENTS
I
GENERAL
This microphone is designed especially for use in com-
puter voice recognition applications. It
is also suitable
for other uses such as paging, talkback, and other
communication-type applications where excellent voice
fidelity and reduction of background noises are needed.
DATA
SHEET
MODEL
VR300
A
The frequency response is tailored to produce an essen-
tially constant output voltage over the voice spectrum
when used close to the sound source. The transducer is
a low-impedance, moving coil type with integral
hum-
bucking coil.
m
The microphone case is aluminum with
a
black enam-
eled finish. It has a standard
5/a"-27 thread suitable for
mounting on a flexible gooseneck, fixed pipe, or micro-
phone stand. The unit is supplied with an attached
two-conductor shielded cable with a built-in strain
relief.
SPECIFICATIONS
m
-
+I0
Z
-
W
U1
:
0
3
W
$
-10
W
20
50
100 1,000 l0,OOO 20,000
FREOUENCY
IN
HERTZ
*Distance from lips to microphone grille
TYPICAL FREQUENCY RESPONSE
FIGURE
1
Impedance
170 ohms actual
Output Level
Open Circuit Voltage*
...........
-41.0 dB (8.9 mV)
Power Level**
.................
-59.5dB
*O
dB
=
1V1100 @bar
**0 dB
=
1
mWI10 ybar
Phasing
Positive pressure on diaphragm produces positive
voltage on white conductor with respect to black
conductor (see Figure 2)
VOICE
HUMBUCKING CABLE
COIL COIL
,-,---------
-
[,r
;
BLACK
Ti;
-I
WHITE
I
-
-
- -
- -
-
-
-
:
SHIELD
=,
INTERNAL CONNECTIONS
FIGURE
2
Hum Pickup
Maximum 15 dB equivalent SPL in 1 mOe field
Cable
1.2m (4 ft) two-conductor shielded
Case
Aluminum with black enameled finish; stainless
steel screen
Dimensions
See Figure
3
Net Weight
128 grams (4.5 oz)
OPERATION
To obtain the best performance with the VR300, the
microphone must be used in a close-talking manner.
Type
The lips should be as close to the microphone grille as
--Dynamic, Unidirectional (cardioid), Close-Talking
comfort permits, with a distance of 1 to 5 cm (0.4 to 2 in.)
Frequency Response
100 to 7,000
Hz
(see Figure 1)
providing the greatest discrimination between voice
and background noise.
Copyr~ght
1982,
Shure Brothers
Inc
27A8048
(BL)
Pr~nted
In
U.S.A.