POLAR
PATTERN
PRESSURE
ZONE
MICROPHONE
®
PZM-20R
PZM-20RW
he Crown® PZM-20R is a Pressure
Zone Microphone® designed for per
T
manent flush-mounting in tables,
lecterns, pulpits, and judicial benches. Its
unobtrusive appearance and hemispherical
pickup pattern make it ideal for conference
table use. The microphone fits into a 4.59-in.
(11.659-cm) square hole or in a standard
4.0-in. x 4.0-in. (10.16-cm x 10.16-cm) elec-
trical outlet box.
Features
•
•
•
Frequency response tailored for speech
clarity
•
•
For permanent flush-mounting in tables
Low-frequency rolloff reduces air-handling
noise
Hemispherical polar pattern picks up every-
one around the microphone
Electronics in the base of the 20R adapt the
microphone for phantom powering. No ex-
ternal power-supply interface is required. The
microphone plugs directly into a phantom
power supply providing 12 to 48 volts.
The wide-range frequency response of the
20R is emphasized at high frequencies for
clarity and articulation. Low frequencies be-
low the voice range are filtered out to reduce
rumble.
Screw terminals provide low-cost connec-
tions
Fig. 1
Specifications
Frequency Response
Type: Pressure Zone Microphone.
+15
+10
Element: Electret condenser.
Frequency response (typical): 80 Hz to 20 kHz (see
Fig. 1).
Polar pattern: Hemispherical on an infinite plane.
Open circuit sensitivity: 7 mV/Pa* (–43 dB re 1
volt/Pa).
+5
dB 0
–5
–10
–15
–20
Three small guard-posts prevent papers from
sliding underneath the cantilever arm and
altering the frequency response.
Power sensitivity: –43 dB re 1 mW/Pa. EIA sensitiv-
–25
–30
ity –135 dBm.
–35
20
Impedance: 240 ohms balanced. Recommended
minimum load impedance 1000 ohms.
10K
100
Frequency in1HK z
Like other Pressure Zone Microphones,
the 20R utilizes the Pressure Recording
Process™ in which a miniature condenser
microphone capsule is arranged very close
to a sound-reflecting plate or boundary, The
capsule is mounted in the “Pressure Zone”
just above the boundary, a region where
sound coming directly from the sound source
combines in-phase with sound reflected
off the boundary. The benefits are a wide,
smooth frequency response free of phase
interference, excellent clarity and “reach,” a
hemispherical polar pattern, and uncolored
off-axis response.
Equivalent noise level: 20 dB SPL (0 dB = 0.0002
Low frequency response depends on size of surface.
dyne/cm2), A-weighted.
S/N ratio: 74 dB at 94 dB SPL.
Maximum SPL: 150 dB SPL at the microphone pro-
duces 3% THD.
Polarity: Positive pressure on the diaphragm pro-
duces positive voltage on terminal 2 with respect to
terminal 3 of the output terminal strip.
Operating voltage: Phantom power, 12 to 48 volts
DC, positive voltage on terminals 2 and 3 with re-
spect to terminal 1 of the output terminal strip.
Current drain: 1.1 mA.
Color: Black.
Connector: Screw terminals. #1 shield, #2 audio in-
polarity, #3 audio return.
Cable: None supplied; use 2-conductor shielded mi-
crophone cable.
Fig. 2A
.250 in.
.635 cm
.187 in.
.475 cm
1.1 in.
2.695 cm
4.58 in.
11.63 cm
Suggestions For Use
Weight: 8.1 ounces (230 grams).
Dimensions: See Figs. 2A and 2B.
Optional accessories: Crown PH-1A phantom power
supply (single channel, battery or AC adapter
powered).
The PZM-20R differs from other PZMs in that
it is a stationary microphone, generally not
moved from one location to another. Before
installing it, first check that the pickup will
be adequate by testing a regular PZM placed
where you plan to install the 20R.
3.42 in.
8.69 cm
4.58 in.
11.63 cm
Avoid areas where items might be placed on
top of the microphone. Once you’ve decided
on the microphone position, rout a recessed
hole according to the dimensions in Fig. 2B
on the reverse side.
3.42 in.
8.69 cm
*1 pascal = 10 dynes/cm2 = 10 microbars = 94 dB SPL.
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