Instruction Manual for DAC3 HGC and DAC3 L with 2.X Firmware Page 40
audio signal, then there is nothing that can be
done to remove the jitter-induced distortion
that happened inside the A/D converter.
Jitter-induced sidebands are extremely
complex and cannot be removed with any
existing audio device. Therefore, it is very
important to attack jitter at both ends of the
audio chain. The DAC3 is a great start, as it
will allow accurate assessment of various A/D
converters. It is impossible to audibly
evaluate A/D performance without a good
D/A. The consistent performance delivered by
the DAC3 eliminates one major variable -
jitter.
Multi-Mode Asynchronous USB
Audio
Plug it in and Start Listening…
Immediately
Benchmark's Advanced USB Audio system
supports the industry standard USB Audio
1.1 and USB Audio 2.0 protocols. These
audio protocols should not be confused with
USB port speeds. The USB Audio 1.1
protocol requires at least a USB 1.0 (Full
Speed) port. USB Audio 2.0 requires at least
a USB 2.0 (High Speed) port.
Benchmark's USB Audio 1.1 and USB Audio
2.0 modes are frequency agile. This means
that the sample rate is controlled by the
computer. The DAC3 will follow sample rate
changes initiated by the computer and/or the
media playback software.
Tip: The USB Audio 1.1 protocol will run on
any USB port, but if it is run on a USB 1.0
(Full Speed) port, it will require all of the
available bandwidth to support 96 kHz sample
rates. If a USB 1.0 port is the fastest port
available, make sure that there are no other
devices sharing the USB hub that services the
port. When possible, connect the DAC3 to a
port that supports USB 2.0 or higher.
Tip: The USB Audio 2.0 protocol is required
for sample rates above 96 kHz. This protocol
will not run on USB 1.0 ports. When possible,
connect the DAC3 to a port that supports
USB 2.0 or higher.
Asynchronous USB
In all modes the USB communications are
asynchronous. An ultra low jitter conversion
clock is generated inside the DAC3. The
asynchronous USB interface pulls data from
the computer without using computer-
generated clocks. The D/A conversion in the
DAC3 is completely isolated by the
asynchronous USB interface and by the
UltraLock3™ jitter-attenuation system.
The DAC3 has a low-jitter master clock which
controls the transfer of audio data from the
computer to the USB sub-system. The
computer asynchronously transfers audio data
to a buffer in the DAC3. The contents of the
buffer are then asynchronously transferred to
the D/A conversion sub-system. This second
asynchronous transfer eliminates any traces
of jitter that accumulate as the data is
transferred between the USB and conversion
subsystems. No traces of jitter-induced
distortion are detectable at our measurement
limits (about -144 dBFS). This truly
represents the state-of-the art. Enjoy the
convenience of computer playback without
compromise.
The Asynchronous USB system supports USB
Audio 2.0 for high-resolution 192kHz, and
DSD playback. No drivers are required for
MAC operating systems. An easy-to-install
driver adds 192 kHz and DSD capabilities to
Windows operating systems.
The asynchronous driverless USB Audio 1.1
mode supports sample rates up to 96 kHz.
This USB mode can be selected from the front
panel or from the remote control. The
driverless USB Audio 1.1 mode allows quick
plug-and-play connections to Windows, MAC,
iOS, and Linux operating systems without
installing drivers. Just plug in the USB, and
the DAC3 becomes an available audio device.
In many cases, audio will automatically be
routed to the newly connected device. If not,
it can be selected as the current or default
playback device.
The industry-standard USB Audio Mode 2.0
mode is not yet natively supported by the
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