Introduction - T+A Elektroakustik DAC 8 DSD Betriebsanleitung

PCM and DSD
DAC 8 DSD
and DSD
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Introduction

Two competing formats are available in the form of PCM and DSD, both
of which are used to store audio signals at very high resolution and
quality. Each of these formats has its own specific advantages. A vast
amount has been written about the relative merits of these two formats,
and we have no intention of participating in the dispute, much of which
is less than objective in nature. Instead we consider it our task to
develop equipment which reproduces both formats as effectively as
possible, and exploits the strengths of each system to the full.
Our many years of experience with both systems have clearly shown
that PCM and DSD cannot just be lumped together; it is essential to
treat each format separately, and take their specific requirements into
account. This applies both at the digital and analogue level.
For this reason the DAC 8 DSD employs two separate digital sections
and two D/A converter sections - each optimised for one format.
By its nature the DSD format involves a noise floor which rises above
the range of human hearing as frequency rises. Although this noise
floor is not directly audible, it does subject the treble units in the
loudspeakers to a significant load. It is also possible for the high-
frequency noise to cause distortion in many low-bandwidth amplifiers.
The lower the DSD sampling rate, the more severe the inherent noise,
and it cannot be disregarded, especially with the 2,8 MHz (DSD64)
format - as used on the SACD. As the DSD sampling rate rises, the
high-frequency noise becomes increasingly insignificant, and with 11,2
MHz (DSD256) it is virtually irrelevant. In the past it has been standard
practice to apply digital and analogue filtering processes in an attempt
to reduce DSD noise, but such solutions are never entirely without side-
effects on sound quality. For the DAC 8 DSD we have developed two
special techniques designed to eliminate the sonic disadvantages:
1. The  True-DSD technique, consisting of a direct digital signal
path without filtering and noise-shaping, plus our True 1-bit DSD
D/A converter
2. Analogue reconstruction filter with adjustable bandwidth.