Instruction manual

DAC1 HDR Instruction Manual Rev I Page 6
AdvancedUSB Audio™
The USB input is compatible with Windows
Vista/XP/2000 and Mac OS X with no driver
installation or system configuration required
(see
www.benchmarkmedia.com/wiki for up-
to-date compatibility information).
Benchmark’s AdvancedUSB Audio™
technology supports sample rates up to 96
kHz and word lengths up to 24 bits.
The DAC1 HDR is a true plug-and-play
solution, and it will be ready for playback
immediately after the unit is connected to a
USB port for the first time.
Jitter-Immune UltraLock™
The Benchmark UltraLock™ system
guarantees 100% jitter-immunity from all
digital inputs. The D/A conversion clock is
isolated from the input digital audio clock in a
topology that outperforms two-stage PLL
designs. In fact, no jitter-induced artifacts
can be detected using an Audio Precision
System 2 Cascade test set. Measurement
limits include detection of artifacts as low as -
140 dBFS, application of jitter amplitudes as
high as 12.75 unit intervals (UI) and
application of jitter over a frequency range of
2 Hz to 200 kHz.
Any signal that can be decoded by the USB or
SPDIF (AES/EBU) receivers will be reproduced
without the addition of any measurable jitter
artifacts. The AES/EBU receiver has been
selected for its ability to accurately recover
data in the presence of very high jitter levels.
HPA2™ Headphone Amplifier
Two ¼” headphone jacks are driven by the
HPA2™ - Benchmark’s signature high-
current, 0-Ohm headphone amplifier. The
HPA2™ is capable of delivering the full
performance of the DAC1 HDR into the
difficult load presented by headphones. The
HPA2™ maintains less than 0.0003% THD+N
under full load.
High-Current Output Drivers
The DAC1 HDR 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.
‘Audio-Always’ Design
Philosophy
The DAC1 HDR is designed to perform
gracefully in the presence of errors and
interruptions at the digital audio inputs. A
soft mute circuit eliminates pops when a
digital signal is applied. Power management
circuitry controls the muting and resetting of
all digital circuits upon removal and
application of power. Audio is present at the
outputs only 60 ms after applying, selecting,
or restoring a digital input signal and only 500
ms after applying power to the unit.
The DAC1 HDR is designed to avoid all
unnecessary mute scenarios. Digital muting
is only engaged either upon loss of power or
when digital transmission errors occur. The
DAC1 HDR does not mute when the AES or
S/PDIF input data is all zeros. Consequently,
no audio is lost when an audio transient
follows full silence. Furthermore, the DAC1
HDR signal-to-noise specifications represent
the true system performance, not just the
performance of an output mute circuit.
The DAC1 HDR will operate even when
sample rate status bits are set incorrectly.
Sample rate is determined by measuring the
incoming signal. Lack of sample rate status
bits or incorrectly set status bits will not
cause loss of audio.
The DAC1 HDR includes non-volatile memory
that saves the state of control settings when
AC power is removed for a period of up to
several hours. The unit will resume normal
operation after interruptions in AC power.