B. Analog Interface
There is provided on the rear of the unit a left/right balanced analog output. This output is suitable
for driving 600-ohm balanced lines and is short circuit protected. A headphone jack and volume
control buttons are provided on the front panel of the unit for confidence monitoring of the
incoming feed. XLR balanced outputs conform to + 4 dBm output referenced to – 20 dBFS digital
output.
III.
Features and Operation
The AES-404 Digital Audio System is designed to select one of four AES3 compatible feeds and
route it to up to two balanced digital outputs. It also contains a high quality digital to analog
converter providing a balanced left and right output. The unit features a front panel headphone
output and volume control for easy confidence monitoring. The AES-404 provides indication of
loss of clock or any error displayed on the front panel. Command of the switcher is performed
manually at the front panel or remotely. Remote control of the unit is accessed through the rear
panel 9 pin D connector for simple momentary closure or through the RS232/485 serial interfaces
on the rear panel of the unit. For simple momentary ground closure to the appropriate pin selects
channels and error reset. Status of channel selected and error flag is also available at this
connector. Refer to the connection table 3 for connection information. The interface is compatible
with open collector command.
IV.
Initial Operating Set up
Attach input and output connections to the unit using the appropriate connector. Plug the remote
control plug in and tighten the connector screws in place. You may select any or all of the error
flag and/or silence sense switching which will command the switcher to switch to the alternate
path. Refer to
AES-404 DIP Switch Programming Guide of Operation
on page 5 for switch
options. Refer to the factory default section of the table for supplied switch conditions. If the
default conditions are satisfactory for your intended use no further changes need to be made. In
order to change the DIP SW 1, 2 settings remove the front panel by removing 1 - #4-40 Phillips
head screw in of the top cover located in the front center of the cover and 4 - #6-32 front panel
screws. The front panel can now be removed and the DIP switches located which are on the front
panel PC board. Other error flags and the silence sense error are selected by placing the
designated DIP switches to the on position. Once DIP switch positions are selected the unit is
ready to be powered up for operation.
Initial Power Application
Upon initial power application the unit will indicate the last channel selected and the channel
selected LED indicator will be lit or flashing which indicates audio level under threshold for at
least 5 seconds. This feature allows the user to determine if audio level is sufficient to drive the
unit or for troubleshooting purposes. This feature can be defeated if desired by setting DIP SW1-6
to the OFF position. In the OFF position the unit will always indicate channel selection with a
steady lighted indication. There should also be an indication of sample frequency. The AES-404
supports any sample rate between 32 and 192 KHz. Standard sample rates are indicated on the
front panel under “Sample Rate” and non-standard sample rates are indicated with the “OTHER”
LED indication being illuminated. Press the error-reset button to clear any errors that might be
indicated. If any of these errors occur after depressing the error-reset button, then the feed to the
unit is defective and should be investigated. If all is in order, the unit is now ready for operation.
All that is left to do is to select the desired feed. When in AUTO mode and an error occurs the unit
will go to manual mode and the “MAN” button and error indication will flash to indicate that an
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