Gilderfluke&Co old MACs 8 bit Digital Audio System - Manual (Page 30)

- Low Level Mixer -
The mixer section of the circuit is used when there are other sources of audio besides the Digital
Audio Repeater. This feature is available on the DR-300 and DR-400 Digital Audio Repeater / Mixer cards.
The other audio sources can be live microphones, RF microphones, film, video, or just about anything
else. There are two external mixer inputs available to each card in addition to the mix input which comes
from the on-board Digital Audio Repeater (DR-300 only). If additional mixer inputs are needed, access is
available to what is known as 'the summing point' through a plug on the back of the card cage.
- Global/Mix Buss -
Four GLOBAL / MIX BUSES are available which can be used to interconnect all the cards in your
system or to feed an audio signal from an external source into the system. Each card can only use one
GLOBAL/MIX BUS function. Typical applications for the Global/Mix Bus are:
¥ Feeding a background audio track to a number of cards to be mixed with their normal
outputs.
¥ Implementing simple 'non-zoned' Public Address systems.
¥ Monitoring the audio in an attraction by feeding a number of audio tracks to a single monitor
speaker.
¥ Sub-woofer and multi-amplifier applications where the outputs of a number of cards are fed to
a single specially filtered output channel.
When configured for use as a MIX BUS, the audio signals from any number of different cards in the
system are fed to one of the MIX BUS lines. This signal, which is made up of the all of the different signals
which are fed to it, is picked up by one other card. It then can be processed through the PA, VCA, and
EQUALIZER systems just like any other signal. Typical uses for this feature are for sub-woofer applications
(where the low end of a number of audio tracks are amplified separately and sent through special low
frequency speakers) or monitor systems (where the sum of any number of tracks are fed to a monitor
speaker which employees can use to check on the progress of a show).
As a GLOBAL BUS, a signal can be fed into any of the four GLOBAL / MIX BUSES from an external
source, or from any one of the other cards in the system. This signal can then be picked up by any
number of cards to be incorporated into their audio outputs. A typical application for this feature would
be to feed a background musical or rhythm track into many of the audio tracks in the scene. This
feature can also be used to send prerecorded 'emergency' or PA announcements to a number of audio
tracks without having to go through the PUBLIC ADDRESS SYSTEM.
The GLOBAL / MIX BUS can be linked between different card cages or left separated. If the card
cages are linked, then any card in the system can be used to send or receive GLOBAL / MIX BUS signals.
If they are kept separate, then each card cage's GLOBAL / MIX BUS can be used locally.
To configure the GLOBAL/MIX BUS, you insert the small configuration cards which were supplied with
your DR- cards into JP-1 (these ÔrewireÕ this section of each card as shown on the following illustrations).
You then must select which bus you are going to use for this card by switching on one, and only one, of
the switches on the dipswitch marked ÔMIX BUSÕ on the card you are configuring. Each card is capable of
using only one of the MIX/GLOBAL BUS features at one time.
The following illustrations shows the six possible configurations available with the GLOBAL / MIX BUS. A
DR-300 is shown, but these same features are available on all DR-100 and DR-400 cards as well.
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