Operation Manual

EF1210 U
SER
M
ANUAL
32 http://www.aspi.com Copyright © 1999, All Rights Reserved
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.
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
2.6. Next, step through the microphone input channels by pressing the I
NPUT
S
ELECT
button, 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.
2.7. When all input channels have been checked, you can mark the positions of the
volume controls on the room audio amplifiers and note that this is the absolute
maximum amplification that may be applied to room audio. This maximum
amplification will be referred to in this manual as the amplifier acoustic gain
limit.
During normal operation, the zone output levels will be set 6 dB lower than the
selected level (amplifier acoustic gain limit) to allow the EF1210 L
EVEL
A
DJUST
con-
trols to apply a volume adjustment to the room audio signal in the range +6 dB to -12
dB.
Refer to Figure 12 on page 31 for further explanation.
C
ALIBRATION
S
TEP
3: C
ALIBRATING
AEC R
EFERENCE
I
NPUTS
3.1. Once the Zone Output channels and room audio amplifier have been calibrated,
press the A
UX
I
N
L
EVEL
/S
ETUP
button again to switch to AEC Reference Input
Note.
You should start by selecting (using the I
NPUT
S
ELECT
button) 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 appro-
priate. Check the acoustic gain of this microphone using Step 5,
then quickly step through each of the microphone channels (step 6)
to verify that no other microphone has a stronger signal.
Note
.
Do not turn up the room audio level at any point after Step 5.
Note
.
The volume control may be set at a lower level than this marked
position (amplifier acoustic gain limit), but must not be set higher
or the performance of the echo canceller will be suboptimal.