T+A PDP 3000 HV User Manual page 53

Set-up option
DSD DAC Mode
DSD signals are characterised by a high-frequency noise floor in the ultra-
sound region. This noise is inherent in the DSD principle, and is present in the
recording itself. In basic terms the higher the sampling rate, the lower the high-
frequency noise. At DSD64 this noise is by no means negligible, and may
constitute a problem for amplifiers and loudspeakers connected to the system.
Although rigorous filtering of the noise is technically possible, these solutions
have undesirable effects on sound quality. In our opinion the filtering option
should always be kept to the minimum necessary level, and that is why the
PDP 3000 HV offers the facility to fine-tune noise suppression, noise-shaping
and signal processing accurately, in order to match the requirements of the
recording, amplifier and loudspeakers.

The settings in this menu point only affect the DSD signals which are fed to the
device via the USB input USB DAC IN.

DAC Mode DSD 1 (standard)
This filter produces a significant reduction in the high-frequency DSD noise
floor, and is suitable for all loudspeakers and all amplifiers.

DAC Mode DSD 2 (high bandwidth)
This filter intervenes in the signal to a minimal extent, and only produces a
reduction in DSD noise at very high frequencies, i.e. above 100 kHz. This
setting requires a very good amplifier with a high bandwidth of at least 100
kHz.

DAC Mode DSD 3
At this setting the device carries out a signal-dependent filtering process.
Low-frequency DSD signals (DSD64) are filtered using the DSD 2 filter
(high bandwidth), whereas DSD signals at higher sampling rates (DSD128,
DSD256, DSD512) are converted using the  True DSD technique.

DAC Mode DSD 4
The  True DSD technique has absolutely no influence of any kind on
the signal: the DSD signal is passed unchanged and uncoloured to the 
1-bit D/A converter, and the bandwidth of the DSD signal is retained in full.
In terms of quality this is the best possible setting, but it is very demanding
on your amplifier and speakers. Your amplifier should exhibit a very good
bandwidth (>150 kHz) with large signals, and very low high-frequency
transient intermodulation.

If the signal is a DSD64 one, the DSD4 setting subjects the tweeter of your
loudspeakers to a much more severe load than the DSD1, DSD2 or DSD3
setting. Please refer to the section "Notes on operation at high DSD
bandwidth".


In the interests of safety it is only possible to select this setting if the menu
point "True DSD for DSD64" has already been set to "On" in the System
Configuration menu.
53