The stereo inputs and outputs of both G4s are connected
the the machine room mixer, which is also connected to a
stereo audio monitor in the machine room.
(If necessary, a mono monitor is acceptable.)
The audio quality of the monitor is of no great importance.
The manifold audio signals
There are signals coming from microphones
in the auditorium; there are signals from the
computers described in the simplistic box
"computer music stuff" on the
Machine room setup
A mixdown of these signals arrives
at the "recording mixer" box pictured in the above illustration.
This mixer supplies whatever mixdown
of these signals is needed by the
recording engineers to make
a high-quality recording of the unique
It would be a good idea to solicit the recording engineers' generosity
in providing a stereo
or mono feed of of this mixdown to outputs
connected to the "mixdown" inputs of the machine room mixer.
The result we call, in our scientific naîveté,
the input from the concert.
Input from the Concert
During the concert, a two-track mixdown from the recording mixer
is sent to the machine room mixer, which reduces the signal to mono and
sends it to the G4s, where it is recorded as a single channel
along with the MIDI data to synchronize the listeners' reactions
and the music they're hearing.
This signal is specified as a stereo signal only because
the machine room mixer can mix it down to mono, since it is likely
that a stereo signal is already available at the recording mixer
as a by-product of the recording process.
However, if it is convienient to mix the
audio signal to mono elsewhere, (perhaps because, after hooking up
all the slider boxes, XLR extension cable is running short),
a mono signal can be used.
In fact, if cable is really running short and stereo mixdown
at the recording mixer is inconvenient,
we can get by with just one channel.
The signal recorded on the G4 is simply for synchronisation, and
only needs to be good enough to tell where we are in the music
for a given MIDI time tag.
Output to the Auditorium
A diagnostic mono output signal goes from the control room
mixer to the auditorium mixer. During installation and testing
of the slider interfaces, programs can be run on the
G4s to send audio feedback to the auditorium
speakers when sliders are moved, so that installers can tell whether
a given slider is working correctly without having to
attempt communication with someone isolated in
the machine room watching the computer screen.
But in addition...
Diagnostic Video projection of G4's Video Signal in the Auditorium (optional)
If it is possible to project the video output from a G4 in the machine
room onto a screen in the auditorium, then a Max patch can be used
all 128 slider values simultaneously on the screen.
This is in some cases a useful supplement to the audio feedback
during installation and testing.
But if this is not trivially easy to do, forget about it.