Pcm And Dsd; Pdp 3000 Hv And Dsd - T+A PDP 3000 HV User Manual

PCM and DSD

PDP 3000 HV and DSD

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 PDP 3000 HV employs two separate digital sections, two
D/A converter sections and two analogue back-ends - each optimised for one
format. Our insistence on optimising and completely separating the PCM and
DSD signal paths is reflected in the fact that the machine features separate
outputs for both formats. Information on the use of the separate outputs can be
found in the chapter entitled "Back panel connections".
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 DSD64 format - as used on the
SACD. As the DSD sampling rate rises, the high-frequency noise becomes
increasingly insignificant, and with DSD256 and DSD512 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
PDP 3000 HV 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 user-selectable bandwidth
The  True-DSD technique is available for DSD sampling rates from
DSD128 upwards. In the System Configuration menu it is also possible to
select it for external 64fs digital signals. However, please note that this is much
more demanding of your amplifier, and may, under adverse circumstances,
subject the treble units of your loudspeakers to a severe load. For more
information on this please refer to the notes in the chapter entitled "Notes on
operation with high DSD bandwidth".

Note: The SACD system fundamentally operates only with a low 64-times
sampling rate (DSD64). Noise-shaping and noise suppression are a fixed,
unchangeable part of the SACD system.Noise-shaping and noise suppression
are a fixed, unchangeable constituent of the SACD system. In SACD mode the
signal processing and signal paths in the PDP 3000 HV are optimised for the
SACD system.
The external USB input is not subject to the limitations of the SACD system,
and is capable of processing DSD sampling rates of DSD64 to DSD512. For
this input the facility exists for matching the internal signal processing of the
PDP 3000 HV accurately to the special requirements of a particular recording
and signal source device. For more details please see the chapter "Basic
settings of the PDP 3000 HV / D/A converter settings".
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