audiopraise VanityPRO, User Manual

Page: 9 / 19

Vanity
PRO
–
User Manual v1.2
Page 9 of 19
DSD Processing Engine
DSD to PCM Conversion
One of the key features of the Vanity PRO is the DSD signal processing and conversion to the
PCM format. We have developed a high quality DSD to PCM conversion algorithm to enable owners
of stand-alone DACs to enjoy their favourite SACDs or DSD recordings in the highest quality
possible. The conversion engine has user adjustable characteristics to slightly vary the frequency
roll-off and subsequently the amount of residual ultrasonic noise inherent to the DSD format. The
user can also control the output sample rate and bit depth.
The DSD to PCM conversion algorithm implemented in the Vanity
PRO
sets 0dB SACD level
equivalent to -3dB(FS) PCM level. This approach preserves maximum quality, provides sufficient
headroom for clipping-free signal peaks and over-modulation, and still does not unnecessarily
reduce playback volume in comparison to PCM playback.
DSD and PCM Level Matching
The DSD to PCM conversion produces overall signal level 3dB lower compared to PCM
playback. This is usually not an issue, but thanks to the precision volume control function, the
output levels of DSD and PCM playback can be matched by attenuating PCM signal by 3dB. A
positive side effect is that this helps to create sufficient headroom for inter-sample peaking with
PCM material and DACs that don’t provide such
headroom by design.
DoP v1 output mode
The Vanity PRO can be also set to output DSD signal in so called DoP format (DSD Over PCM).
This allows the user to send raw DSD material directly to a DoP compatible DAC. More details can
be found here:
http://dsd-guide.com/sites/default/files/white-papers/DoP_openStandard_1v1.pdf
DSD 4.0 Down-Mix
To achieve the best performance during digital DSD playback, it is essential to avoid the
DSD to PCM conversion done by the HDMI source. Universal players can sometimes perform such
task for downmix purposes. For this reason, the widely used 4.0 speaker configuration is covered
by the dedicated down-mix algorithm implemented in the Vanity PRO . The algorithm preserves the
overall signal level balance between channels, and it can be described as follows.
FL
mix
= 0.5FL+0.25C+0.25LFE
FR
mix
= 0.5FR+0.25C+0.25LFE
SL
mix
= 0.5SL
SR
mix
= 0.5SR
To fit the mixed Center and Low-Frequency Effect channels into the front channels, the
overall signal level is shifted by -6dB. No additional signal normalization or scaling is applied.
Since the down-mix processing is carried out with full precision, there is no adverse effect on
sound quality such as reduced dynamics or worse noise figures. The 4.0 downmix can be
performed correctly only with multi-channel 5.1 DSD tracks. If the Vanity PRO is connected to a
universal player, the SACD playback priority should be checked or correct setting.