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Sending a 1x word clock signal into the BNC WC Input.
Sending a 256x word clock signal into the BNC WC Input.
Sending an AES/EBU or S/PDIF signal into the Digital input.
The BNC word clock input port is a 110 Ω internally terminated coaxial input. It should be
driven by a 110 Ω source driver and interconnected with 110 Ω coaxial cable. If you do not use
proper cabling and source drive, you will introduce reflections on the word clock cable which
will propagate jitter into the recovered word clock and your final output. This is true whether
you use the port as a 1x WC input or a 256x WC input, but becomes more important when the
clock signal is 256x.
1x is generally appropriate for use with devices that provide a word clock output. If your de-
vice provides a 256x output, you may find that you get better results using that clock signal.
The Digidesign© line of Pro Tools© products use 256x as their “Superclock” clocking reference.
The AES recommended procedure for distributing clock is to use an AES clock signal. The AES
clock signal is an AES digital audio signal with no audio activity. Series 300 models uses only
the AES preambles for clock recovery, so it is immune to data–dependent jitter effects. This
means you can reliably use the Digital Input as a clock source with or without audio data.
2.5 FireWire
FireWire© is Apple’s registered trademark for the IEEE 1394 high speed serial bus. FireWire
started as an Apple technology to replace a variety of interface ports on the back of the com-
puter. After promulgating a number of closed proprietary technologies in the early days of the
Macintosh, Apple determined that open standards were better for the Mac, for the industry,
and for Apple itself. On that basis they opened their technology for standardization under the
auspices of the Institute of Electrical and Electronics Engineers, Inc. (IEEE), an international
organization that promotes standards in the field of electronics. FireWire was standardized as
IEEE 1394 and promoted for open licensing in the industry.
The first widespread adoption of the technology was for DV camcorders where space was
at a premium and bus powering was not percieved as a real issue since all camcorders have
batteries. Sony designed an alternative version of the standard 6 pin FireWire connector that
provided 1394–based communication with 4 pins in a much smaller form factor. This version of
the connector sacrificed bus power support and mechanical stability for reduced space require-
ments. Sony dubbed this version “i.Link©.” This became the de facto standard in the DV world,
and was later added to the IEEE 1394 standard. Both i.Link and FireWire refer to the same un-
derlying standard and are completely interoperable. Obviously, i.Link connectors and FireWire
connectors cannot be used together without adapters.
Series 300 models uses the 6 pin implementation of FireWire for bus power support. The unit
ships with a 0.5 meters long, about 18 inches. If you want to use your Series 300 with a 4 pin
FireWire device, you will need to purchase a 6 pin to 4 pin adapter cable. These cables are
available from a wide variety of retail sources. If you are using a 4 pin cable to connect any
device to the computer with Series 300 models, bus power will not be available.
The 6 pin FireWire connector is keyed by its shape, as one end of the connector is pointed. The
FireWire ports on Series 300 models point downwards toward the bottom of the box. It will be
very difficult to insert the connector upside down, but it is possible if you force it. If the plug is
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