Output Level Switch; Balanced Xlr Analog Line Outputs - Benchmark DAC1 PRE Instruction Manual

to allow interfacing to a wide variety of audio
devices without any loss of dynamic range.

Output Level Switch

The Output Level Switch is a
three-position toggle switch
located on the rear panel. The
DAC1 PRE ships with this
switch set in the Variable
position.
CAUTION: Do not set the 'Output Level
Switch' to 'Calibrated' if you are directly
driving a power amplifier or powered
speakers. The 'Calibrated' setting
disables the front panel volume control
and will produce an output that may be
too loud for your speakers.
Calibrated (UP) – Analog output levels are
controlled by 10-turn internal trim controls
(see page 14 for information on calibration
trimming).
Off (CENTER) – Analog XLR and RCA outputs
are muted; headphone outputs remain active.
Variable (DOWN) – Analog output levels are
controlled by the Volume Control.
The Output Level Switch does not affect the
operation of the headphone jacks (the
headphone outputs are never disabled and
the headphone level is always controlled from
the Volume Control).
TIP: If the DAC1 PRE is being used in a
critical signal chain (such as a broadcast
facility or theater) the headphone mute
switch should be defeated using the
internal jumpers. See 'Internal Settings'
section for instructions.
DAC1 PRE Instruction Manual Rev J

Balanced XLR Analog Line Outputs

The Left and Right balanced outputs use
Neutrik™ gold-pin male XLR jacks. The XLR
shell and pin 1 (ground) are both directly
bonded to the chassis to prevent currents in
the internal ground systems. This direct
bonding also maximizes RF shielding.
The XLR output levels may be controlled from
the front panel, or may be set to fixed levels
using the internal Calibration Trimmers.
The XLR outputs have passive attenuators
that allow direct connections to a wide variety
of audio devices without a loss of dynamic
range. The 20 dB pad is usually required for
direct interfacing to power amplifiers and
powered speakers. The DAC1 PRE ships with
the 20 dB pad enabled.
Industry-standard XLR wiring:
XLR pin 2 = + Audio Out
XLR pin 3 = - Audio Out
XLR pin 1 = Cable Shield
CAUTION: If the balanced XLR outputs
are wired to an unbalanced input (using
a special adapter cable), pin 3 must be
left floating. Shorting pin 3 to ground
will increase the temperature of the
output drivers, will increase power
consumption, and may cause distortion.
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