External Microphones
3.09 When the background noise level
is
so
high
that
the called party may have difficulty hearing,
external microphones located in closerproximity tothe
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-houroperational 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 extensioncord
will
be required.
PRACTICE 512-6261-200
3.12 On completion
of
the
CONFERENCE
2000
installation, the operation testsdescribed
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.
Lowerlevels of
SJlCech
donotoperatethe voice
switching circuit and, consequently, are not
transmitted Thelevel
of
speechmustbe 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, itshould 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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