DAC1 USB
Instruction Manual Revision D
Page 13
Analog Outputs
The
DAC1 USB
has two unbalanced RCA
outputs and two balanced XLR outputs.
The
DAC1 USB
features new high-current
output drivers that are capable of driving
300-Ohm loads without an increase in
distortion. They are also well suited for
driving long cables or high-capacitance loads.
Note:
The XLR and RCA output levels are
controlled by the
Volume Control
level when
the
Output Level Switch
is set to variable.
Otherwise the levels are set by the 10-turn
calibration trimmers located on the rear
panel.
The XLR outputs are equipped with low-
impedance passive output attenuators that
can be set at 0 dB, -10 dB, -20 dB, or -30 dB
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 USB
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
produces an output that is near full-
volume and may damage your speakers.
Calibrated (UP)
– Analog output levels are
controlled by 10-turn rear-panel trim controls.
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 USB
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’
for instructions.
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 rear-panel
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 USB
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
