Consoles 993commonplace in broadcast installations, and the
morphing of the concept to using high-bandwidth UDP
pipes was a natural and welcome progression from
running lots of discrete signal lines.
Having a central hub from and to which all network
runs are connected is a concept as old as the phone
system. As such, it has similar strengths and weaknesses
in that cable runs are logical and obvious, but reliability
hinges on that of a central server. Although this would
seem a vulnerability, a single point of failure, parallel
and redundant methodologies are common, as will be
seen.
The switch in audio terms is in fact a router, which
accepts large numbers of sources and can redistribute
them in any combination to large numbers of destina-
tions. Ofttimes many sources and destinations are local
to the router, but more often high-density audio pipes as
described above of, say, 64 discrete signals bidirection-
ally, spur out to remote locations, where these pipes are
terminated in input and output terminations of whatever
nature and complexity are desired. (If all the outputs
need to be analog on XLRs, so be it. AES pairs, no
problem—termination styles are easily accomplished to
suit the application. If local-specific signal processing is
desired, no problem.) These pipes are simply arranged
to look like multiple sources and destinations to the
router and are treated as such. The router also parses
any metadata, logic control, or metering that accompa-
nies each audio path and routes or deals with each of
these accordingly. (Losing the meta data or sending it to
the wrong place is like the airline losing your bags: it
isn’t the end of civilization, as you’ve arrived, but
you’re nowhere near as equipped to accomplish what
you have to do.)
This centralized router model works well in the
broadcast environment, radio or TV, where much of the
engineering work is clustered in a central racks room
anyway; likely many of the sources and destinations of
the router would be local to it in that room, easing inter-
connection, with spokes of high-density audio transport
issuing out to each studio and production area—Some-
thing of a natural for the star topology.
Live sound benefits from this method more than
others (such as serial), too. A typical setup is for two
consoles (house and monitors) to each be recipients of
all stage audio sources or at least major subsets of them.
In this instance the router would receive the outputs
from the active stage boxes as sources and distribute
them as required by transport links to the two consoles.
Returning from the consoles to the router are:- House—main mixes and/or speaker processor
outputs - Monitors—many, stage monitor mixes
These enter the router and are then sent by further links
to the desired amplifier racks for the flown and/or
stacked PA and sub-low cabinets, or indeed straight to
the powered speakers themselves; and to the amplifier
racks for the stage monitor speakers and the transmitter
rack for in-ear monitoring.
Additional feeds, such as for recording, are assem-
bled in the router and sent to the band’s DAW or the
recording truck and terminated accordingly.25.25.3.3.3 Mixing in the RouterA progression from the notion of a router being a simple
crossbar or summing switch is that it becomes a soft
matrix, where the relative levels of sources and destina-
tions may be varied. In other words, a mixer. Or a
number of smaller mixers than the total capability
described by possible numbers of inputs and outputs.
And, taking a step further forward, given the already
signal-processing-intensive environment, the
console-style signal processing on mixer inputs,
outputs, and submixes becomes relatively easy to
implement.
Nodes in a TCP/IP system, or breakout boxes in
serial network schemes, often contain varying amounts
of processing, all the way from simple access to slots to
being a full-scale mixer. It is common for the router to
have processing capability, indeed for it to be where the
mixing/processing parts of consoles reside; it makes
sense, since all the possible component signals to be
mixed exist within the router or can be got there expedi-
tiously enough through one or several links. Fig. 25-155
shows a large-format TV audio mixing console in which
there is not a shred of audio—it is merely a control
surface, controlling the signal processing/mixing else-
where within a processing router: Fig. 25-156. That the
console system is or is part of a router means that the
number of available mix sources is limited only by the
size of the router and can so extend to the thousands.
From an operating perspective, however, the console is
limited to mixing only as many sources instantaneously
as it has faders; this can be multiplied by paging the
surface, such that it can flip-flop either entirely or on a
fader-by-fader basis to control multiple other channels;
instantaneous channel counts can thus run into the
hundreds, and on big live shows (such as election night)
often does.