Crown PZM-20R User manual

PZM-20R
PZM-20RW
PRESSURE
ZONE
MICROPHONE®
Fig 2A
®
The PZM-20R is a Pressure Zone
Microphone®designed for perma-
nent flush-mounting in tables, lec-
terns, pulpits, and judicial benches. Its un-
obtrusive 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) electrical 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 phan-
tom 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.
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 Pro-
cess™in which a miniature condenser mi-
crophone capsule is arranged very close to a
sound-reflecting plate or boundary, The cap-
sule is mounted in the “Pressure Zone”just
above the boundary, a region where sound
coming directly from the sound source com-
bines in-phase with sound reflected off the
boundary. The benefits are a wide, smooth
frequency response free of phase interfer-
ence, excellent clarity and “reach,”a hemi-
spherical 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. Be-
fore installing it, first 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.
Specifications
Type: Pressure Zone Microphone®.
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).
Power sensitivity: –43 dB re 1 mW/Pa. EIA sensi-
tivity –135 dBm.
Impedance: 240 ohms balanced. Recommended
minimum load impedance 1000 ohms.
Equivalent noise level: 20 dB SPL (0 dB = 0.0002
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
respect 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
microphone 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), Crown PH-4B phantom power
supply (4 channels, AC powered).
*1 pascal = 10 dynes/cm2= 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

Crown International, Inc.
P.O.Box 1000
Elkhart, IN 46515-1000
TEL: [phone]
FAX: [phone]FAX
@crown®
©1999 Crown International, Inc.
Specifications subject to change without prior notice.
Crown®, PZM®and Pressure Zone Microphone®are
registered trademarks of Crown International, Inc.
Pressure Recording Process™ is a trademark of E. M.
Long Associates.
3/99 102362-2
PZM-20R Schematic
MICROPHONE CAPSULE
▼
R1 R6
BLK T1
+ GRN BLU R4
R5
R2
R3
+
+
RED
ELECTRONICS
1
2
3
OUTPUT
SCREW
TERMINALS
2
3
1
C1
C2
C3
B+
AUDIO
RED
ORG
GRY
R1
Q1
PZM-20R
PZM-20RW
®
®
Fig. 2B
For small conference tables seating up to
eight people, mount the 20R in the center of
the table. For larger tables, use one 20R in
the middle of every four to six people. Ide-
ally no person should be more than 3 feet
from the nearest microphone. For maximum
clarity hold the conference in an acoustically
“dead”room with carpeting, acoustic-tile
ceiling and drapes.
Operating Instructions
Using two-conductor shielded microphone
cable, connect the output of the 20R to a
mixer microphone input that provides 12-48
volts phantom powering. This cable may be
of any length because the microphone out-
put is balanced low impedance.
The 20R has three screw terminals. Connect
screw #1 to the cable shield, #2 to the audio
in-polarity lead, and #3 to the audio-return
lead. On the equipment end of the cable, sol-
der the cable to the XLR-type connector as
follows: pin 1 –shield, pin 2 –audio in-
phase lead, pin 3 –audio return lead.
If your mixer or recorder does not provide
phantom powering, you’ll need a micro-
phone power supply. Crown offers a model
PH-4B power supply for powering up to four
PZMs. Also available is a single channel AC/
battery supply, Crown model PH-1A. Con-
nect the 20R output to the power-supply in-
put; connect the power-supply output to
your recorder or mixer mix input.
Architects’ and Engineers’ Specifications
The microphone shall be the Crown Model
PZM-20R or equivalent. The microphone
shall be a Pressure Zone, electret condenser
type, designed for permanent flush-mount-
ing in 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) electrical outlet box. A smooth
frequency response from 80 Hz to 20,000 Hz
shall be obtained. The microphone shall
have a sensitivity of –43 dBV/Pa (measured
on an infinite boundary). The microphone
shall accept a 150 dB SPL input while pro-
ducing no more than 3% THD (open-circuit
termination). Equivalent noise shall be typi-
cally 20 dBA (0 dB = .0002 dyne/cm2). The
Crown model PZM-20R is specified.
Warranty
Crown professional microphones are guar-
anteed unconditionally against malfunction
from any cause for a period of three years
from date of original purchase. Please refer
to the enclosed full warranty sheet for more
detail.
Service
If the microphone does not function prop-
erly, replace or repair mic cables and con-
nectors, check the power supply. If service
is required, return the microphone in its
original packaging to: Crown Service De-
partment, Plant 2 SW, 1718 W. Mishawaka
Road, Elkhart, IN 46517. For further assis-
tance or technical support call 800-342-
6939.
++
+
+
A
(4) PILOT HOLES FOR ROUTER
0.25 in. (0.635 cm) RADIUS
(USE 0.5 in. (1.27 cm) ROUTER BIT)
A
4.094 in.
10.399 cm
4.59 in. (11.659 cm) SQUARE
0.188 in. (0.476 cm) ROUTER DEPTH
2.75 in. (6.985 cm)
SQUARE
TABLE
TOP
4.094 in.
10.399 cm