Northern Airborne Technology AA82 - Manual (Page 10)

AA82 InterMUSIC™ Stereo Intercom System
SM09-1 Installation and Operation Manual
Section 2 Rev: 1.00 Issue 4 Page 2-4
ENG-FORM: 805-0117.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.5.1 Radio Settings
To achieve correct radio volume settings, check that the headset radio level is acceptable. This
adjustment should be made with the radio volume set to about 50%. Adjust the headset volume control
(if it exists) for something less than full volume, such as 75% (full output on active headsets will give the
worst over-all signal to noise ratio, as it will increase the low level noise floor). Adjust the RX VOL on the
side of the AA82 to a preferred level.
Check that the music is muting at this stage when a radio signal is received. If not, the radio itself set too
low and must be increased at the radio to properly activate the internal muting circuit in the AA82. Once
the radio settings are satisfactory, perform all other adjustments. The RX VOL trimpot sets only the radio
level heard during normal operation and has no effect on any other function, including muting.
2.5.2 Setting Up Muting and Music
Rotate the front panel VOX potentiometer until the VOX indicator is off. The music audio can now be
heard. Adjust the music to a comfortable level with the front panel potentiometer. If the music is louder in
one ear than the other, the side panel MUSIC BAL control may need adjusting, although this could be a
problem with your music source, as this adjustment should be correct from the factory.
With the front panel VOX potentiometer turned fully counter-clockwise (LIVE ICS, the indicator should be
ON), adjust the MUSIC MUTE trimpot to the desired level of music audio in the background. This is the
level the music will default to whenever it is muted and can range from OFF to only slightly muted as
preferred.
2.5.3 Setting Balance and Bass Potentiometers
With the VOX control still in the LIVE ICS position, talk back and forth on the intercom to determine the
voice quality. If more bass is desired, the ICS BASS potentiometer may be adjusted for the preferred
tone. Check that this adjustment is compatible with the headsets and that it does not increase distortion. If
the ICS audio seems distorted, reduce the ICS BASS potentiometer for best results. Some aircraft
headsets do not have very good internal microphone amplifiers and achieve "noise reduction" by shunting
the microphone with a large capacitor to reduce high frequency noise. This may make the voice very bass
heavy and muffled. Best results were obtained in NAT testing with the following headsets:
Bose (may require re-wiring of plug for stereo)
David Clark (may require modification for stereo)
Most aircraft headsets do not do a good job of reproducing wide bandwidth music information, which
seriously compromises the performance of the AA82. NAT will test any headset for system compatibility if
the unit is supplied for evaluation with the AA82.
If you wish the ICS audio to come from a particular location (left to right), adjust the ICS BAL
potentiometer for the desired position.
Note: If you have not controlled the Left/Right headset jack wiring, it may appear to change locations
between different users.
Set the location to suit your preference, listen to an incoming radio transmission and position it (ideally) in
the opposite location with the RX BAL trimpot. The best setup should give some perceived difference in