Manual

Model 44D User Guide Issue 3, August 2018
Studio Technologies, Inc. Page 15
to –20 dBFS in the digital domain. While in
Europe (EBU) it would be typical in modern
installations for 0 dBu (analog) to be equal
to –18 dBFS (digital).
But SW1 can be used as a coarse level
adjustment function if necessary. In a
SMPTE-compliant installation (+4 dBu =
–20 dBFS) setting SW1 to its on (up) posi-
tion will provide a 6 dB increase in input
sensitivity. This could be useful if the aver-
age level of the signal connected to the
line inputs was a little low. And in an EBU
application setting SW1 to its off (down)
position would provide a 6 dB decrease in
input sensitivity. This could be useful if the
analog signals connected to the line inputs
were especially “hot.”
Line Output Nominal Level
Switch SW2 is used to configure the nomi-
nal level of the Model 44D’s two line output
channels. When SW2 is in its off (down)
position the line outputs are configured
such that a Dante input (receiver) channel
with a signal level of –20 dBFS will result in
an analog signal at the corresponding line
output channel having a level of +4 dBu.
This configuration would allow compat-
ibility with SMPTE digital-to-analog level-
relationship standards. When SW2 is in its
up (on) position a Dante input (receiver)
with a signal level of –18 dBFS will result
in an analog signal at the corresponding
line output channel having a level of 0 dBu.
This relationship will make the line output
compliant with EBU standards.
The choices provided by SW2 are primar-
ily intended to allow the Model 44D’s line
output gain structure to match the needs
of specific applications. Most North Ameri-
can (SMPTE) applications will follow
–20 dBFS in the digital domain being
equal to +4 dBu in the analog domain.
While in Europe (EBU) it would be typical
in modern installations for –10 dBFS (digi-
tal) to be equal to 0 dBu (analog).
SW2 can be used as a coarse level
adjustment function if necessary. In a
SMPTE-compliant installation (–20 dBFS
=+4 dBu) setting SW2 to its on (up) posi-
tion will provide a 6 dB decrease in input
sensitivity. This could be useful if it’s desir-
able for the average level of the line output
signals to be less than typical. This can
be useful when a true “+4 dBu” output is
simply too “hot.” And in an EBU application
setting SW2 to its off (down) position would
provide a 6 dB increase in input sensitivity.
This could be useful if the average level on
the Dante input (receiver) channels is lower
than expected and a “hotter” analog output
is desirable.
Low-Pass Filters
Switch SW3 allows a low-pass filter func-
tion to be enabled or disabled as desired.
The function consists of four digital filters,
two applying to the audio signals from
the line inputs and two applying to the
signals destined for the line outputs. When
active the filters will eliminate most of the
audio content above 10 kHz that enters the
Model 44D by way of the line inputs and
exits the Model 44D by way of the line
outputs. When SW3 is in its off (down)
position the low-pass filters are disabled.
Figure 5. Analog outputs nominal level
configuration switch