Operation Manual

EF1210 U
SER
M
ANUAL
A-10 http://www.aspi.com Copyright © 1999, All Rights Reserved
If you selected only one of the Zone Outputs, repeat for the second Zone Output.
Check Acoustic Gain.
iii. At this point you are ready to calibrate the absolute maximum room audio ampli-
fication level. For this step, you should ensure that the microphones have been
returned to their normal operating location and orientation. This procedure uses
a known nominal electrical noise signal level at the zone output to let you see if
any of the microphone input channels will exceed the permissible acoustic gain
during normal conferencing operation. The level of this noise signal is such that
if any microphone input channel registers more than three green LEDs on the
EF1210 I
NPUT
S
IGNAL
L
EVEL
M
ETER
, the acoustic gain limit of that microphone
channel has been reached. This represents the maximum amplification that may
be applied to the room audio. The room audio may be run at any level below this
threshold, but should not be amplified beyond this level unless the acoustic gain
is reduced by some other means (see the Troubleshooting section in the EF1210
User Manual).
All microphones should be checked in this step as verification that no micro-
phone inputs or zone outputs have been miscalibrated.
As above, both Zones can be adjusted at the same time (both AEC A and AEC B
LEDs will be lit indicating Zone A and Zone B). This is recommended because
you can check all Input Channels at the same time. Alternatively, if necessary,
you may select either Zone by pressing R
EF
S
ELECT
until the appropriate AEC
LED is lit and check one Zone at a time.
You should start by selecting (from the radio buttons labeled 1 through 8) and
checking the microphone input channel which is closest to the loudspeakers or
the microphone which might be expected to pick up the most acoustic energy
from the loudspeaker audio, as appropriate. Check the acoustic gain of this
microphone using Step a, then quickly step through each of the microphone
channels to verify that no other microphone has a stronger signal.
Check and make adjustments for acoustic gain by doing the following:
a. Adjust the external room audio amplifiers/loudspeakers until either:
• The loudspeaker audio level is about to become uncomfortably loud.
OR
• Three green LEDs on the EF1210 I
NPUT
S
IGNAL
L
EVEL
M
ETER
are lit, but
the first yellow (0 dB) LED is not lit for the chosen input channel
b. Next, step through the microphone input channels by choosing each input
channel from the radio buttons labeled 1 through 8, while verifying for each
channel that the first yellow (0 dB) LED is not lit on the I
NPUT
S
IGNAL
L
EVEL
M
ETER
.
• If the first yellow (0 dB) LED is lit for any channel, turn down the room
audio amplifier on the corresponding zone output or turn down the gain on
that microphone channel.
c. When all input channels have been checked, you can mark the positions of
Note.
Do not turn up the room audio level at any point after Step a.