Benchmark Media Systems, Inc.
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not decode AC3 signals. A red
Non PCM Error
LED will illuminate when AC3 or other non-PCM input signals are
connected to the selected digital input. Internal jumpers can be used to disable the front-panel selector switch.
These jumpers allow the permanent selection of any one of the three digital inputs. This feature is useful for
applications where the DAC1 has a dedicated function in a critical audio path.
XLR Digital Input:
This input uses a gold-pin Neutrik™ female XLR connector. The input is balanced and has a 110-Ω input
impedance. This input is DC isolated, transformer coupled, current limited, and diode protected. It is designed to
accept standard 4 Vpp AES signals, and will work reliably with levels as low as 300 millivolts. Receive errors will
occur (and the DAC1 will mute) when the peak-to-peak input voltage is less than about 160 millivolts.
Coaxial Digital Input:
The coaxial input uses a female BNC connector that is securely mounted directly to the rear panel. The input
impedance is 75 Ω. This input is DC isolated, transformer coupled, current limited, and diode protected.
Like the other digital inputs, this input accepts AES/EBU or S/PDIF digital audio formats. The BNC connector is
specified by the AES3-id and SMPTE 276M standards for 75-Ω 1 Vpp digital audio signals and is commonly used
in video production facilities. IEC 609588-3 specifies the use of an RCA type connector for 75-Ω 0.5 Vpp
consumer-format digital audio signals (commonly known as S/PDIF). The coaxial input on the DAC1 is designed
to accept either type of signal. We have chosen to use a BNC connector because of its superior reliability. The
DAC1 comes with a BNC-to-RCA adapter to allow easy interface with consumer equipment.
The BNC input has a 75-Ω internal termination that may be disabled by removing a jumper. This termination is
required for normal operation, but may be removed if the user wishes to loop a single coaxial feed through several
other pieces of equipment. A 75-Ω termination must be applied at the last device on the loop, and there should
be a combined total of less than 6 feet of cable between the first and last receive device.
Optical Input:
The optical input connector is manufactured by Toshiba and is commonly known as a TOSLINK connector. The
TOSLINK optical connector used on the DAC1 is designed to work well at sample rates up to 192 kHz.
AC POWER INPUT CONNECTOR AND FUSE HOLDER:
The AC power input uses a standard IEC type connector. One USA compatible power cord is included with
DAC1 converters shipped to North America. IEC style power cords in country specific configurations are
available in your locality.
The fuse holder is built into a drawer next to the IEC power connector. The drawer requires two 5 x 20 mm 250 V
Slo-Blo
®
Type fuses. The drawer includes a voltage selection switch with two settings: “110” and “220”. The fuse
rating for the 110-Volt setting is 0.50 Amps. The fuse rating for the 220-Volt setting is 0.25 Amps.
The AC input has a very wide input voltage range and can operate over a frequency range of 50 to 60 Hz. At
“110”, the DAC1 will operate normally over a range of 90 to 140 VAC. At “220”, the DAC1 will operate normally
over a range of 175 to 285 VAC.
Caution:
Always install the correct fuses when changing the voltage setting. Always insure that the voltage
setting is correct for your locality.
