User`s manual

User's Manual
8. CABLE RECOMMENDATIONS
8.1. Cat5 cable
Cable Quality
Cat5 cabling is commonly used, cheap, with a huge selection on the market to choose from. With the ADX
devices, any cable that meets Cat5 or higher (e.g. Cat5e, Cat6, Cat7) can be used. A higher “Cat” number cable
has no electrical advantage over a basic Cat5 type, because the parameters where the higher graded one
performs better are only important for much faster systems, like Ethernet applications.
However, if mechanical robustness is an important issue, it is recommended to use a ruggedized Cat5 cable with
Neutrik® EtherCon® connectors. Ready-to-use cable drums are available from several vendors; good value for
money, stage-proven Cat5 cable drums are made by Adam Hall, for example.
Technology
Cat5 cable consists of four twisted pairs, each made up of two single wires. One pair can carry one ADAT stream
(8 channels), yielding a total transmission capacity of 32 channels. The transmission method used on the media
is called “differential pair signaling” or “balanced transmission”. This means that each signal is transmitted over a
wire pair, where one wire carries the inverted signal of the other one. In contrast to unbalanced (ground-
referenced) systems, differential signaling provides very good noise immunity, because coupled noise affects
both wires the same way and can be cancelled out at the receiver's side by subtracting one wire's signal from the
other. Additionally, EMI is greatly reduced because the electric and magnetic fields surrounding the two wires
cancel each other out.
The technology used in the ADAT Multicore Extender (RS-485) has been used for a long time, e.g. for lighting
applications (DMX) or harsh industrial environments (Profibus). The commonly used AES/EBU standard works in
a similar manner, but is, due to its relatively low data rate, only able to transmit two audio channels over one pair.
State-of-the-art technology is used in the ADAT Multicore Extenders to ensure reliable operation at the higher
data rates required by the ADAT protocol.
8.2. Toslink (Lightpipe) cable
Cable Quality
Toslink cables are generally not critical if you don't exceed their length limit of 5m (16ft). Quality cables usually
provide a tighter fit (=better latching) in the jack than cheaper ones, and may perform better on longer runs.
Technology
Plastic Optical Fiber (“POF“) cables are cheap and immune to electromagnetic interference, but are limited in
reach. Larger runs cause problems as the light pulses are attenuated too much, leading to data errors which
usually result in drop-outs or crackles. Furthermore, POFs are also very sensitive to breaks and sharp bends
which may be a problem in harsh stage environments.
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