HBA09-001-70
HB-NEDSP1068
7
Disabling the AGC Action
For certain applications the AGC system may need to be disabled such that the pre-
amplifier is not limited in any way. To disable the AGC circuit, locate and remove R16
on the underside of the 1068 PCB as shown below.
If the AGC system is disabled the user should be aware that too higher gain setting
could give rise to overdriving of the DSP device, which may then cause it to malfunction.
The Overload indicator should operate under these circumstances to help prevent this
happening, but prevention is preferable and will make the module more reliable.
Underside of 1068 PCB showing location of R16
6.1.8 Setting the output level
Whilst the modules have been preset during manufacture, you will probably need to
carry out minor adjustments to ensure that you have the required output level and the
best response under all signal conditions for your application.
With the module connected to your system, apply power and check the audio
performance.
Before going any further, reduce the noise cancelling level or switch the noise
cancellation facility off – see Noise Cancelling settings (para 6.1.9).
Using the maximum audio level that your system is likely to encounter, check that the
Overload LED is illuminating. Adjust potentiometer P2 (Audio in) to ensure that the LED
illuminates and then back it off until there is just the odd flash on the LED.
Adjust potentiometer P1 (Out) for the required audio level into your system.
To disable AGC remove R16
