Instruction Manual for DAC3 HGC and DAC3 L with 2.X Firmware Page 36
32-bit SABRE-PRO D/A System
Four balanced 32-bit D/A converters deliver
audio to Benchmark's low-impedance current
to voltage converters. The 4:1 redundancy
reduces noise by 6 dB. The redundancy also
reduces the THD. The conversion system at
the core of the DAC3 is as good as it gets.
The analog circuits that follow the D/A
converter are carefully designed. Benchmark
has leveraged its long history of building
reference analog audio equipment to create
an outstanding output stage.
Diagnostic Displays
Ever wonder why that 192 kHz 24-bit
download on your computer just doesn't
sound right? Your media player or computer
may be downsampling to 44.1 kHz and/or
truncating to 16-bits. Many media players and
computer operating systems apply poor-
quality sample rate conversion and/or
truncation. Fortunately these problems can be
eliminated with the selection of a good
frequency-agile media player.
Many disk players also downsample all
sources to 44.1/16. This processing can do
significant damage to the audio quality.
The sample-rate and word-length displays on
the DAC3 confirm the proper operation of
your disk player, media player, and computer.
Bi-Directional 12 Volt Trigger
Benchmark has re-invented the 12 volt
trigger. The trigger connection on the DAC3
can be used as an input or output or both,
and is compatible with any common 12 volt
trigger input or output. The trigger can be
used to turn a power amplifier on or off
automatically. The DAC3 will also respond to
a 12 volt trigger and follow the actions of
another audio component.
Benchmark components can communicate bi-
directionally on the trigger I/O ports. This
bidirectional communication provides greater
flexibility. In a given system, the power
button on any Benchmark device can be used
to start or stop the entire audio system in a
sequenced manner.
Distributed Power Regulation
To achieve the lowest possible noise, the
DAC3 uses distributed power supply
regulation. Each critical subsystem has at
least one dedicated low-noise voltage
regulator.
We have created a discrete ultra low-noise
regulator for the ES9028PRO D/A converter.
This Benchmark exclusive feature improves
the noise performance of the already-
outstanding ES9028PRO.
HPA2™ Headphone Amplifier
The DAC3 headphone output is driven by
Benchmark’s signature HPA2™ headphone
power amplifier. This high-current, high-
output amplifier has an output impedance
that is nearly 0 Ohms. It is designed to drive
loads as low as 30 Ohms without any increase
in distortion. It also has sufficient amplitude
to drive low-sensitivity 600-Ohm headphones.
The HPA2™ includes current-limiting circuits
that fully protect against damage from short
circuits. This is important because the right
channel of a headphone amplifier will
experience a short whenever a mono phone
plug is inserted into the stereo headphone
jack. Shorts may also occur when a plug is
partially inserted.
"0-Ohm" Output Impedance
Most headphone amplifiers use series
resistors to maintain stability and protect
against short-circuit conditions. These
resistors are usually at least 30 Ohms, and
have a negative impact on performance. A
headphone amplifier with series resistors may
measure very well on a test bench when
driving resistive loads. However, the same
amplifier will measure very poorly when
driving a headphone load. Unfortunately,
most manufacturers do not measure or
specify headphone amplifier performance
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