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APPENDIX A: Special Functions
A.1 A/D level
Except for the Pure Audio inputs, all other analogue inputs will be converted to
digital samples (A/D conversion) by the built-in 24 bit 96kHz high quality A/D
converter. The digital audio samples are then used in the DSP circuit e.g. for further
processing, e.g. Dolby ProLogic II.
However, a fundamental problem by A/D conversion is that the peak analogue input
level should be as close as possible to the maximum input range of the A/D
converter, otherwise the important dynamic range will be degraded.
On the other hand, the peak analogue level must under no circumstances exceed
the maximum analogue limit for the A/D converter, or severe clipping will occur.
In the AV100/120 is included an auto-gain feature, which operates as follows:
When an input is selected, the high sensitivity position is initially selected for
obtaining best dynamic range. If clipping occurs, the sensitivity is automatically
reduced. During changes in sensitivity, a small click can be heard, which is not a
malfunction.
A.2 Electrical (coaxial) versus optical digital input.
Normally, a coaxial connection between e.g. DVD and processor has been preferred
to an optical by HiFi-enthusiasts due to larger bandwidth and consequently less jitter
on the receiver side.
However, with the increasing complexity of a surround system that integrates
analogue, digital and video signals, it is easy to create disturbances and ground
problems in any system.
To create a worthy alternative, the optical transmitters and receivers in the
AV100/120 are a new type featuring a substantially increased bandwidth of 13MHz
compared to the normal 7MHz type. This eliminates most traditional problems with
the optical connection, and the advantage with full galvanic isolation is clear due to
far less sensitivity to hum.
If any problems in the system with ground loops or disturbances appear, it is
advisable to change the digital connection from coaxial to optical.
A.3 Automatic failure correction system
A special “watch dog” in the AV100/120 will monitor all DSP (Digital Signal
Processor) operation as well as the control ICs. If any external disturbances like
lightning, transient bursts on the mains net, or static discharge causes the DSP to
crash, the DSP will automatically be reset for correct operation. This is performed in
a fraction of a second, and only a short dropout in the sound will be audible.
During standby, the entire system in AV100/120 is reset. If any problem occurs with
the operation of AV100/120, please set the unit into standby for a few seconds.
If standby does not cure the problem, please turn off the mains switch on the rear
panel before turning back on.
With the many different settings in AV100/120, it is possible to select a setting,
which does not match the installed system and cause the unit to malfunction. If
malfunction is observed, and a standby/operate command does not help, then run
the factory default resetting described in the config menu followed by a
standby/operate command.
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