Violectric dac v850 User Manual page 23

The internal frequency of the digital signal (and potential interference
therein) is very high in comparison with the useful analog frequencies.
Therefore, the subsequent analog low-pass filters have to meet less
severe requirements in terms of high-frequency roll-off and can
therefore be realized as "musical", discrete two-pole filters.
Without careful consideration of the analog output stages it wouldn't
have been possible to make the outstanding performance of the top-
notch converter available at the analog outputs.
In case of DAC V850, the converter is followed by an amplifier specially
designed for this purpose, with a topology similar to an instrumentation
amplifier.
It distinguishes itself by a wide dynamic range, minimum distortion and
high flexibility with regard to the achievable output level.
Within this amplifier, the output currents of the D/A converters are
transformed into voltages, while any interferences and processing
frequencies are completely removed.
Gain - i.e. output level – can be set by means of DIP switches over a
very wide range. An error amplifier caters for minimum DC offset.
From the D/A converters to the rear outputs the signal remains
completely balanced.
The unbalanced outputs are generated by differential amplifiers from the
balanced signal lines.
Only now follows the output driver stages, feeding the output signal to
the corresponding terminals at extremely low impedance.
The balanced and unbalanced outputs can be used at the same time,
since they are buffered individually. Output impedance for all outputs is
significantly lower than 1 Ohm.
Four muting relays in the output lines serve for (nearly) pop-free action
during powering on or off.
23