Dacs; Outputs - MSB Technology Select DAC II User Manual

There is not much that you need to know about the heart of the DAC. The digital processing is incredibly advanced and can be fully
upgraded by simply playing an MSB upgrade file. There are 8 two channel Hybrid DAC modules that can also be upgraded when the
time comes.
The SELECT uses two of the latest DSPs for ultra fast processing and has an expansion header for future hardware upgrades.
The SELECT has the optimum digital filter installed for each sample rate. They are extremely large FIR filters.
Upsampling
Upsampling has been in and out of vogue for many years. Its benefit has been historically obvious in some DACs and nonexistent in
others. Typically the most processor intensive task in a DAC is the digital filtering. A digital filter takes a look at a window of the music
being played, and because that music was received from a digital source, there are holes in it, between data bytes. The filter looks at the
shape of the signal in the window and tries to figure out what the missing data is. The bigger the window, the better a job it does, and
the bigger processor is needed.
Depending on the sample frequency of the incoming data, a different digital filter is run. Each is a little different and each may not
sound the same. As a result, CDs at 16 bit and 44.1 kHz might sound better or worse than 24 bit 96 kHz files in a particular DAC. But
generally, the higher the sampling frequency, the more processor power can be applied to look at a bigger window and the better job the
digital filter can do. So back in the days of very limited DSP power, upsampling was a great way to get a little more out of the digital
filter. Today with extremely fast DSPs, this limitation is not significant, and it is better to operate directly on the native stream. For that
reason MSB does not support upsampling in the SELECT.
External Preamp
Because of this incredible output resolution and amazingly low noise, it is a major compromise to use an external preamp, which adds
many opamps, filters and output drivers, increasing the system noise and adding phase errors. The DAC is the lowest noise part of the
system. All amplifiers are higher noise so the difference between amplifiers should be very obvious with this DAC. Power issues will
also be very obvious and great care should be taken when dealing with bad power.
If for some reason you do want to use an external preamp, set the volume to 94. This is the lowest noise output possible and should give
you the best results without your preamp clipping.
Digital Processing and DACs
10

OUTPUTS

There is one output module slot.
There are two versions of the output
modules, a single ended and a
balanced. This design approach
allows an optimized design and
output. If your system changes,
these modules can be swapped out.
The output module contains some of
the most advanced MSB technology.
The outputs are a constant 75 ohm
output impedance regardless of the
setting of the passive volume control
without the addition of a output
buffer, opamp or transistor output
stage. This for the first time allows
you to hear the full resolution of
the DAC.
Output Levels
Balanced Outputs 10 Volts PP
(3.5 V RMS) at a volume of 100.
Impedance is 75 ohms
Single Ended Outputs 7.8 Volts PP
(2.8 V RMS) at a volume of 100.
Impedance is 75 ohms.