Balanced Analog Line Inputs; Aux Bnc Output; Main Bnc Output; Toslink Optical Output - Benchmark ADC1 USB Instruction Manual

RCA adapters. These adapters allow easy
interfacing with consumer-style digital
interfaces. BNC to RCA coaxial cords are also
available from Benchmark.
BNC connectors are specified by the AES3-id
and SMPTE 276M standards for 75-Ω 1 Vpp
digital audio signals and are commonly used
in video production facilities and other
professional audio applications. RCA
connectors are specified by IEC 609588-3 for
75-Ω 0.5 Vpp consumer-format digital audio
signals (commonly known as SPDIF). We
have chosen to comply with the professional
standards because the BNC connectors lock
and are generally more reliable than RCA
connectors. Compliance with the 1 Vpp digital
audio standards increases the reliability of
digital connections, and often allows
increased transmission distances.

1) Balanced Analog Line Inputs

Left and Right balanced inputs use locking
Neutrik™ gold-pin female XLR jacks. These
inputs have a wide operating range. The input
sensitivity (at 0 dBFS) ranges from -20 dBu
(at maximum gain) to +29 dBu (at minimum
gain). The input impedance is 200k Ohms
balanced, and 100k Ohms unbalanced. The
high input impedance and input sensitivity,
allow direct connections from many
instrument pickups (adapter cable required).
Direct connection of piezo pickups is not
recommended as these pickups require higher
input impedances (to prevent low-frequency
roll-off problems).
• XLR pin 2 = + Audio In
• XLR pin 3 = - Audio In
• XLR pin 1 = Cable Shield (grounded
directly to the chassis to prevent
internal ground loops)
Unbalanced Source Adaptation
1. Connect "+" or hot (tip on ¼ phone plug,
center pin on RCA plug) to XLR pin 2.
2. Connect ground (sleeve on ¼" phone
plug, case on RCA plug) to XLR pins 3 and
1.
ADC1 USB Instruction Manual
Note: It's best to used balanced wiring ("+",
"-", "shield") and to tie the "-"and "shield" at
the unbalanced connector.

2) Aux BNC Output

This Aux BNC digital output has the unique
ability to output two different bit rates. The
first is a 16 bit TPDF auxiliary output for use
with low-resolution devices. The second signal
is the Main digital output and is identical to
the data available to the other Main digital
outputs.
• Data Format = AES/EBU professional
format
• Word Length = 16 bits TPDF dithered,
or 24 bits
• Sample Rate = 44.1 or 48 at 16 bits,
44.1, 48, 88.2, 96, 176.4, or 192 kHz
at 24-bits
• Clock Source = Internal at 16 bits,
internal or external at 24 bits

3) Main BNC Output

The digital data output from the Main BNC
Output is identical to that of the Main XLR
Digital Output.
• Data Format = AES/EBU professional
format
• Word Length = 24 bits
• Sample Rate = 44.1, 48, 88.2, 96,
176.4, or 192 kHz
• Clock Source = Internal or external

4) TOSLINK Optical Output

The Optical Output has four modes of
operation; AES/EBU, ADAT, ADAT S/MUX
4
and ADAT S/MUX . The ADAT LED on the
front panel is illuminated whenever any of the
ADAT Modes are active. S/MUX
are automatically enabled if required to
support the selected sample rate. S/MUX
active at 88.2 or 96 kHz, S/MUX
176.4 or 192 kHz.
The Optical Output uses what is often called a
TOSLINK, Type FO5, or 5 mm optical
connector. The ADC1 USB uses a special high-
bandwidth version that supports AES/EBU
2
,
2 4
and S/MUX
2
is
4
is active at
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