Software Instruction Manual

IQ–MSD Turbo 1.4 Advanced IQ System Software
Page 159
6.4.10 AMB Function (AMB-5 Mixers Only)
(Figure 6.18) The AMB function is unique to the AMB-5 mixer. The AMB function monitors the ambient sense input
(Input 6) and automatically adjusts the mix output level of Channel 1 up or down accordingly. This enables the
AMB-5 to automatically mix and control the overall loudness in an environment with background noise levels that
vary. For example, it can insure that a factory paging system will never be too quiet or too loud when noisy
machinery turns on and off.
The AMB function operates
after all other functions have processed the audio signals. You can think of the AMB
function as a “black box” which sits after all other automatic functions.
There are external factors that can greatly affect how well this functions works. The two most important ones are
the location of the ambient sense microphone and the location of the loudspeakers. The ambient sense micro-
phone must be located in a position where it can pick up the ambient noise level without also picking up unwanted
sounds. The ambient sense microphone must also be located far enough away from the loudspeakers so that
they do not inadvertently trigger the AMB function. It may take some experimentation to find both the optimum
location for the ambient sense microphone and the optimum settings for this function.
Tip: Unwanted sounds can often be filtered out with a band-pass filter or by using an ambient sense micro-
phone with a selective pass band. For example, a 500–4,000 Hz band-pass filter could be added so the sense
input responds only to the noise which would interfere with speech intelligibility. Also, a high-pass filter could be
added so the sense input does not pick up low-frequency air conditioning noise (which can sometimes be very
loud).
Tip: Shield the ambient sense microphone from excessive wind noise so that it does not prematurely activate
the AMB function.
WARNING: The AMB function bases its operation on the Gate function Max Gain settings for each input. It is
extremely important that the Max Gain settings be set properly to prevent exces-
sive levels which could cause feedback.
Fig. 6.18 The Fifth AMB-5 Sub-block Screen