Introduction; Applications; Dac2 Vs. Dac1; Dac2 Technologies - Benchmark DAC2 D Instruction Manual

Introduction

Applications

The DAC2 D is a professional reference-grade
audio digital to analog converter with
Benchmark's HPA2™ headphone amplifier.
The DAC2 D supports 24-bit D/A conversion
of PCM at sample rates up to 192 kHz. It also
supports direct conversion of 1-bit DSD at a
2.8224 MHz sample rate. It is designed to be
very transparent and this makes it well-suited
for critical monitoring in studio control rooms
and mastering rooms.
The DAC2 D is also well-suited for high-end
hi-fi environments. It includes a generous
collection of inputs and outputs and can serve
as the central component in any stereo hi-fi
system. The DAC2 D provides D/A
conversion, source selection, volume control,
and headphone amplification. A remote
control and a home theater bypass function
provide the features needed in a home
environment.
The DAC2 D is designed to directly drive a
wide variety of power amplifiers and powered
monitors. The balanced outputs include low-
impedance passive pads that can be adjusted
to optimize the interface between the DAC2
D and the power amplifier. This optimization
can provide substantial improvements in the
system-level SNR and THD+N performance.

DAC2 vs. DAC1

The DAC2 D adds these features that are not
found on the DAC1:
 Asynchronous 192kHz USB Audio 2.0
 32-bit D/A conversion system
 Word Length Display
 Sample Rate Display
 Polarity Control
 Direct DSD D/A Conversion
 -20 dB DIM
 Power Switch with Auto-On Function
 Home Theater Bypass
 Digital Pass-Through
 High-Headroom DSP
 Dual-Domain Hybrid Gain Control
 Additional I/O
Manual for DAC2 D with 2.X Firmware - Rev. H

DAC2 Technologies

4:1 Parallel Conversion Structure
The conversion system in the DAC2 achieves
a 6 dB signal to noise improvement through
the use of 4:1 summing. The ES9018 D/A is
an 8-channel 32-bit converter. In the DAC2,
four channels are summed in the analog
domain to form each of the two output
channels.
The 4:1 summing also improves the THD. The
non-linearities in individual conversion
channels are averaged across the four
summed channels and incoherent non-
linearities are attenuated by 6 dB.
High-Headroom Digital and Analog
Processing
The DAC2 has generous amounts of analog
and digital headroom. The analog clip point is
above 29 dBu. The digital clip point is 27.5
dBu. When operating at a typical -20 dB at
+4 dBu studio calibration, the DAC2 has 3.5
dB of digital headroom above 0 dBFS. This
digital headroom prevents the clipping of
intersample overs.
No Clipping of Intersample Overs
The DAC2 is one of very few D/A converters
that can accurately reproduce intersample
overs without clipping. Intersample peaks can
reach +3.01 dBFS and commonly occur many
times per second in most 44.1 kHz and 48
kHz recordings. When recordings are ripped
using lossy compression systems (such as
MP3), additional intersample overs are often
created. Most converters (including the
DAC1) produce bursts of distortion at every
occurrence of an intersample over. In
contrast, the DAC2 converters cleanly
reproduce all intersample overs.
Low-Noise Power Supplies
The DAC2 uses high-efficiency low-noise
power supplies. Each critical subsystem also
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