V O R S I S H D P 3 G U I
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HD P3 / Aug 2006
Transmission path emulation.
Particularly when an HD P3
is being retrofitted into an exist-
ing airchain path, or one which
maybe does not allow the flex-
ibility to early-pre-emphasize, as
above, the HD P3 may be used to
internally capture, control and
so neutralize any downstream
“surprises” from pre-emphases
in STLs, exciters, or encoders.
This is achieved by pre-em-
phasizing at the “Input”, and
complementarily de-emphasiz-
ing at the “Output”. In this way,
the processing “sees” a pre-em-
phasized signal (such as would
exist in an STL and/or sender)
and can control it appropriately,
catching things and handling
them perhaps more gracefully
than the more rudimentary limit-
ers downstream might. Additionally, a fully processed yet “flat” signal is
available for monitoring; DJs like to hear the processed signal, rather than
the usually much less exciting sounding console output.
So, in short: The pre-emphasis is to emulate that required of a typical
transmission scheme. By bringing it into the HD P3, superior control over
the overall signal path, and superior airchain processing, may be achieved.
The de-emphasis in the box allows for normalization of a pre-emphasized
signal within the box either for monitoring, or where a “flat” signal is
required for onward passage.
M/S
This is a technique for stereo used in many places for different reasons,
and is often known as “Sum / Difference” processing.
An “M/S” switch, as implemented in the HD P3, will turn a conven-
tional left/right stereo pair of signals into a sum-and-difference pair; the
“left” path then becomes a mono sum of the applied left and right signals,
the “right” path now carrying the difference (left minus right) of the
applied pair. Conversely and conveniently, the same “M/S” processing
turns an applied sum-and-difference pair into their constituent left and
right signals. Neat, eh?
The HD P3 has “M/S” switches at both “Input” and “Output”. This
allows a wide range of additional processing possibilities:
