Gilderfluke&Co 16 Bit CD-Quality Digital Audio Systems - Manual (Page 19)

feature can be turned off for running Gilderfluke & Co. equipment from systems that canÕt generate a
checksum.
A UDIO O UTPUTS :
The normal audio output from the AB/DR-3000 is a balanced +10 dB line level. The output driver is a
SSM-2142 transformerless output driver. This chip is compensated for driving standard 600 ohm bal-
anced audio lines. If running to a single ended amplifier, you will need to ground the unused output. If
you donÕt, the output will be excessively noisy.
Several digital output options are available with the AB/DR-3000 series of repeaters. They allow audio
data to be sent to your amplifiers in a completely digital form for absolutely no noise and distortion. All of
these options require a digital output driver chip be installed on the AB/DR-3000, and a special condi-
tioning card on the back of the card cage
14 . These conditioning cards provide the proper signal levels
and connectors for running the signals to your amplifiers in one of three industry-standard formats. These
are:
a) AES/EBU: Three position XLR connector for running balanced digital signals to your amplifier.
b) SPDIF: RCA connector for running single ended digital signals to your amplifier.
c) OPTICAL: Fiber optic connector for running optical digital signals to your amplifier. Surprisingly,
this is the most economical digital link to use.
When running digital output signals from the AB/DR-3000s, the normal analog outputs remain active
and usable.
SMPTE I
N AND
O
UT
:
SMPTE (pronounced Òsimp-TÓ) is a time code which was developed by the Society of Motion Picture
and Television Electronics (SMPTE) for use in audio, film, and television production. It is normally recorded
on a spare audio track on the medium being used (audio tape, video tape, or film), and then used to
synchronize various pieces of compatible equipment together. As an industry standard, virtually every
audio, video or film studio in the world will have the equipment to support a SMPTE time code track.
SMPTE is usually recorded at thirty frames per second. Twenty-five frames per second is used in
Europe and places where this is the normal television frequency. Twenty-four frames per second is occa-
sionally used in film production. What this means is that 30 (or 25 or 24) times each second a number is
recorded on the tape or film. This number represents the hours, seconds, minutes and frame
(00:00:00.00) for this particular little stretch of film or tape. Since each little stretch is represented by a
unique number, SMPTE is known as an ÔabsoluteÕ time code. No matter where the tape is, the AB/DR-
3000 will instantly evaluate the numbers it gets from the SMPTE time code to figure out where it is.
If enabled, AB/DR-3000s generate SMPTE time code whenever their LEFT channel output is playing.
This is whenever a stereo sample is being played back, but only when the Left channel is playing if mono
ROMs are installed.
When generating SMPTE time code, the AB/DR-3000 will start at zero minutes, frames and seconds
(00:00.00). The hour number generated is taken from the spiel number being played. For spiels num-
bered one to ninty-nine, they are displayed as-is. If there are more than ninty-nine spiels on a repeater,
they are displayed using the hexadecimal numbering system.
The only frame rate the AB/DR-3000s will generate is 30 FPS, non drop frame 15 . Note that the actual
frame rate generated by the DR-3000 is slightly off from an actual 30 Hz frequency. Over the course of
a 10 minute spiel, it will get off by about one second from the actual time. Additional error can also be
generated by drift between the crystal that is used for audio reproduction and the one that is used by
the microcontroller. Any equipment which is synchronized to the AB/DR-3000 system should never so
small an error.
One of the advantages of programming a show to a SMPTE time code is that it is easy to start and
stop a tape or just back up a little. The disadvantage with a repeater is that they always insist on starting
at the beginning of a spiel. We recommend that before you program a show you generate a ÔscratchÕ
G ILDERFLUKE & C O . ¥ 205 S OUTH F LOWER S T . ¥ B URBANK , C ALIF . 91502-2102 ¥ 818/840-9484 ¥ FAX 818/840-9485
11
14 This plugs right into the AB-3000.
15 ÔDrop FrameÕ time code literally ÔdropsÕ a frame every few seconds.