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POLAR
PATTERN
PZM-20R
PZM-20RW
Fig. 2A
®
T
he Crown
®
PZM-20R is a Pressure
Zone Microphone
®
designed for per
manent fl ush-mounting in tables,
lecterns, pulpits, and judicial benches. Its
unobtrusive appearance and hemispherical
pickup pattern make it ideal for conference
table use. The microphone fi ts 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.
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 fi ltered out to reduce
rumble.
Three small guard-posts prevent papers from
sliding underneath the cantilever arm and
altering the frequency response.
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-refl ecting 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 refl ected
off the boundary. The benefi ts are a wide,
smooth frequency response free of phase
interference, excellent clarity and “reach,” a
hemispherical polar pattern, and uncolored
off-axis response.
Suggestions For Use
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, fi rst check that the pickup will
be adequate by testing a regular PZM placed
where you plan to install the 20R.
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.
Specifi cations
Type: Pressure Zone Microphone.
Element: Electret condenser.
Frequency response (typical): 80 Hz to 20 kHz (see
Fig. 1).
Polar pattern: Hemispherical on an infi nite plane.
Open circuit sensitivity: 7 mV/Pa* (–43 dB re 1
volt/Pa).
Power sensitivity: –43 dB re 1 mW/Pa. EIA sensitiv-
ity –135 dBm.
Impedance: 240 ohms balanced. Recommended
minimum load impedance 1000 ohms.
Equivalent noise level: 20 dB SPL (0 dB = 0.0002
dyne/cm
2
), 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.
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).
*1 pascal = 10 dynes/cm
2
= 10 microbars = 94 dB SPL.
Fig. 1
–20
–25
–30
–35
20 100 1K
+15
+10
+5
dB 0
–5
–10
–15
10K
Frequency Response
Frequency in Hz
Low frequency response depends on size of surface.
4.58 in.
11.63 cm
3.42 in.
8.69 cm
.187 in.
.475 cm
.250 in.
.635 cm
1.1 in.
2.695 cm
4.58 in.
11.63 cm
3.42 in.
8.69 cm
Features
• For permanent fl ush-mounting in tables
• Hemispherical polar pattern picks up every-
one around the microphone
• Frequency response tailored for speech
clarity
• Low-frequency rolloff reduces air-handling
noise
• Screw terminals provide low-cost connec-
tions
PRESSURE
ZONE
MICROPHONE