III.
Inputs and Outputs
1.
Power, Power Switch, and Power LED
Make sure the voltage selector switch on the IEC connector is set to the appropriate voltage for
your locale. Power can be 50Hz or 60Hz, and the voltage selections available are 110V and
240V. The voltage indicator indicates the selected mains voltage. The power switch on the front
of the unit applies power to the unit’s internal power supply.
A power LED is located on the front panel below the power switch. This LED will begin to blink
when power is applied. The blinking will continue (for about a minute) while the ADC is executing
its power-on calibration sequence. After the converters have been calibrated, the LED will remain
lit. Once the blinking stops, digital audio will be output from the unit.
2. Inputs, Signal/Clip LEDs, and Input Trim
Input signal levels can vary from typical consumer “-10” type sources to professional “+4” types
and beyond. Input trim adjustments are provided on the front panel to assist in matching levels
to a variety of sources. “Consumer” audio sources will usually require the greatest input
sensitivity. Setting the Input Trim fully clockwise may provide the best matching for these types
of devices. “Pro” audio sources, on the other hand, will typically output a much higher nominal
level. A setting labeled “+4” has been provided to accommodate sources with these higher
signal levels. An intermediate setting has also been provided, labeled “-3”.
Finally, a lowest trim setting is available for use with certain audio sources which can provide
very high output levels. Higher end mixing consoles, as well as many types of outboard gear
often achieve very high “headroom” or dynamic range by being capable of generating signals in
excess of +20dBu! The BLA ADC can easily handle outputs from these sources with the setting
labeled “+11” (fully counterclockwise) on the front panel.
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