PATHS ANd PORTS
Paths and Ports
On an analog desk, the channel inputs
are physical connections to the channel
module or card. They are fixed. Channel
1’s input is always channel 1’s input (even
though it may be possible to control
channel 1 from a different fader). Every
channel will probably have both a mic and
a line input, even though most will only use
one of them at any one time.
In a digital desk, there are two basic types
of input: mic/line and digital. However, it
is not necessary to provide both types for
every channel, as only one input will be
used at any one time. To provide both types
for each channel would increase the cost,
size and power consumption of the desk
unnecessarily.
Instead, a “pool” of each type is available,
plus an internal matrix to allow any of
them to be connected to any channel. This
provides more flexibility than is possible
with analog designs. The matrix can be
thought of as an electronic patch-bay with
the advantage that any connections made
will be stored with the console’s memories.
A similar matrix and “pool” is provided for
the outputs which is also stored with the
memories.
Each channel can select from two inputs
(1 and 2), which can be any combination
of mic/line and digitaI. Both inputs can
be set up independently, using separate
input controls ( input gain, phase reverse,
phantom power, etc). The switching
between the two inputs takes place after
these controls.
The basic terminology is that channels,
groups and mains are referred to as “paths”
within the digital processing system, and
the inputs and outputs are referred to as
“ports” through which the audio signals
have to pass. Ports are connected to paths
via the Matrix.
All ports are optional, including those
for the monitoring. The system can be
supplied with any combination of mic/line
and digital ports. Calrec digital consoles
are available in a number of configurations
known as Audio Packs, which are a
suggested complement of ports. The
Audio Pack which most closely matches
the requirements of the installation can be
chosen, and the port quantities can be fine
tuned appropriately.
Port Labels
During installation, all the ports on the
system are labelled to match the studio
wiring. Some rules are imposed on this
labelling:
Inputs and outputs should be labelled
•
in pairs.
The label must be no more than six
•
characters (to fit on the console’s
displays).
The same label cannot be used more
•
than once (but an input can have the
same label as an output) - to avoid
confusion.
Inputs and outputs are labelled in pairs for
easier use with any type of signal; mono,
stereo or surround. As digital inputs and
outputs are wired in pairs and it makes
sense to deal with all the inputs and
outputs in the same way.
The system automatically adds a left
(L) and right (R) suffix to the label to
distinguish the two halves of the pair, or an
LR suffix when the pair is used together.
The pairs can be used either for two mono
signals, or a stereo signal, or parts of a
surround signal. This includes the digital
ports if the external circuit allows them to
be used for two mono signals.
Those inputs or outputs which are
dedicated externally to mono signals only
(telephone lines, mono reverbs, mono
distribution feeds, etc), can be specified as
being mono. In this case, the two halves
of the pair have separate labels and the
L & R suffixes are not applied. Inputs and
outputs labelled in this way cannot be
connected in pairs to stereo paths.
Port Lists
In addition to labelling, each port may
be allocated to one of a number of lists
using the Options - Port List Screens.
This allows inputs and outputs which are
wired for similar purposes to be grouped
together for selection. Each list can
contain a mixture of normal inputs or
outputs (labelled in pairs) and inputs or
outputs dedicated to mono signals.
The lists can be sorted into the order
in which they appear on the selection
screens. The lists will appear in the same
order on the I/O Matrix and I/O screens.
It is possible to restrict the lists which
appear on the I/O Matrix using the Options
- Misc screen. This ensures that only the
relevant lists are immediately available at
the user’s fingertips. All lists are always
available on the I/O screens.
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