Instruction Manual for DAC3 DX with 2.X Firmware - Rev. B Page 7
Benchmark’s unique motor-driven volume
control sets the gain of a 32-bit dithered
digital gain control. The 32-bit digital output
feeds the 32-bit D/A conversion system.
The 32-bit digital gain control delivers low
distortion, accuracy, and precise left-right
gain matching. The noise-free 32-bit dithered
system preserves musical details over a very
wide range of output levels.
The XLR outputs leverage the low-impedance
passive analog attenuation system. When
properly configured, the entire dynamic range
of the DAC3 DX can be lined up with the
dynamic range of the power amplifier. This
matching can provide a dramatic
improvement in the system-level signal to
noise ratio.
The volume control is a servo-driven analog
potentiometer. This control rotates in
response to commands from the remote
control while providing the convenience of
manual adjustments with a physical knob.
The potentiometer produces a DC voltage that
controls the gain of a dithered 32-bit
multiplier. The outputs of the multiplier drive
the 32-bit D/A converters.
Low-Impedance Passive Attenuators
Like the DAC1 and DAC2, the DAC3 includes
low-impedance passive attenuators on the
XLR outputs (Page 16).
These attenuators can be adjusted in 10 dB
steps to optimize the interface with the power
amplifier or powered monitors. This
optimization places the volume control in its
best operating range. This exclusive
Benchmark feature can provide substantial
improvements in the overall performance of
the playback signal chain.
Native DSD Conversion
The DAC3 DX supports native DSD
conversion. This feature was not available on
the DAC1. DSD signals can be delivered to
the USB or Coaxial inputs in DoP 1.1 format.
The DSD signal is then routed directly to a
bank of 1-bit DSD D/A converters. Three
balanced 1-bit converters are summed
together for each of the MAIN outputs.
Digital Pass-Through
The second coaxial input (D5) can be
reconfigured as a digital output (Page 16).
When D5 is configured as an output, any
selected digital input is passed through to D5
without any processing. Optical, XLR, coaxial,
and USB inputs can be passed through to the
D5 connector. PCM and DoP formatted DSD
can both be passed through the D5 connector
while also being sent to the D/A converter.
The pass-through function even works with
special signals such as DTS, Dolby Digital,
even though these signals cannot be decoded
by the DAC3 DX.
Volume Control Bypass
The CALIBRATED mode can be activated for
either or both output buses (Page 16).
The factory default calibration at 0 dBFS is
+24 dBu on the XLR outputs (pads at 0 dB)
and 2 Vrms on the RCA outputs. If your
studio calibration is different, the calibration
can be adjusted in 1 dB increments from +20
dBu to +28 dBu using the removable jumpers
on connector P6.
The Mand/or Alights will be on when the
MAIN and/or AUXILIARY outputs are in the
CALIBRATED mode. A slow flashing light
indicates that a calibrated output is muted.
The DIM function is disabled on any output
group that is operating in CALIBRATED
mode.
When the CALIBRATED mode is off, the M
and/or Alights will flash rapidly when the
volume of the MAIN and/or AUXILIARY
outputs are being adjusted.
