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External Microphones
3.09 When the background noise level is so high that
the called party may have difficulty hearing,
external microphones located in closer proximity to the
participant may improve the transmission
quality.
When more than one external microphone (
customer-
provided) is essential, a standard microphone mixer
(customer-provided) is required.
Notes: Customer-provided microphones should
meet the following specifications:
• Dynamic
• 10,000 ohm impedance
•
1/4
in.
(6.4mm)
plug.
Although 600-ohm, electret-type lapel micro-
phones perform well, the battery requirement
(3- to 6-hour operational use) may lead to frequent
battery replacement.
3.10 The microphone mixer should be centrally
located, adjacent to the acoustic unit. This ensures
that the external microphones are positioned approxi-
mately equidistant from the acoustic unit.
Note: Commercially available active mixers
( equipped with self-contained amplification cir-
cuits) can be connected to the CONFERENCE
2000 mixer jack located at the back of the control
unit. When external microphones are in use, the
microphone switch on the front of the control unit
must be set to the mic ext position.
3 .11 When the microphone mixer cable is not
long
enough to provide a central location for the
acoustic unit, an add-on extension cord will be required.
PRACTICE 512-6261-200
3.12 On completion of the CONFERENCE 2000
installation, the operation tests described in Chart
1
must be performed
4. OPERATION
4.01 For best operation, the following distance and
speech guidelines should be observed:
•
Conference
participants should be
seated
not
closer than 3 ft (0.9m) or further than IO ft
( 3
.1
m) from the acoustic unit
• Speech should be at normal conversation level.
Lower levels of SJlCech do not operate the voice
switching circuit and, consequently, are not
transmitted The level of speech must be raised
as the distance from the acoustic unit is
increased.
Note: The voice-switching circuit permits trans-
mission of speech in one direction at a
time.
The
circuit switches to transmit when you speak and
to receive when the distant party responds.
4.02 The acoustic unit represents the called party.
Speech should be directed toward the acoustic
unit at all times. Speech directed away from the unit
sounds hollow at the called party location.
S. MAINTENANCE
5.01
If
the CONFERENCE 2000 must be returned
for repair, it should be packaged using the cartons
listed in Table A to protect against damage during
shipping.
5.02 The CONFERENCE 2000 should be treated as
a piece of fine furniture ( especially the acoustic
unit), and should not be subjected to temperature
extremes during use, storage or shipment
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