U-Net; Ethernet - Martin Audio MLA User Manual

MLA System
USER GUIDE
connectors in the popular Socapex pattern used very commonly with lighting systems. Each array whether it is a flown MLA, MLA
compact or Combination array or a ground stack sub array requires a mains connection from one of the outlets. The most
common configuration is with one Master Rack stage left and a slave rack stage right each with a single distro. A mains feed is
routed from one outlet each side using a 30m Tourmate cable up to the flown array where it is connected to a 12-way breakout
loom. The second outlet can either go directly into a six-way breakout loom to drive the MLX or DSX subs if they are sufficiently
close by, or via a second 30m Tourmate cable and then into the six-way breakout. Each breakout loom is terminated in 16A
CeeForm connectors which connect directly to the cabinets, all of which have a 16A IP67 rated inlet.

U-Net

All MLA components need to be connected to a U-Net Network to upload optimisation files and for control and monitoring. U-
Net is a protocol not unlike Ethernet but with a number of enhancements and extra features. The cable used is rugged Cat5e
using ODU connectors to the Lemo K Series pattern. The Merlin controller is used as a PC interface and has two U-Net ports with
which to connect all system components. All components have a pair of U-Net ports labelled 1 7 2 and essentially used as an
"in"and "out". U-net is run as a redundant loop so that in the event of a cable failure communication will continue seamlessly.
Up to 254 devices can reside on a single ring and cable runs can be up to 120m between nodes. It is important to note that every
connection added to a cable run reduces the usable length by approximately 3.5m. For very large systems several Merlins can
be employed each with up to 254 devices. Commonly a Merlin is used stage left and stage right to keep the network cabling
easier to manage.
The U-Net ports on the Merlin are brought out on Neutrik Ethercon connectors so can be used with either Ethercon cable
connectors or a simple RJ45. These are brought out onto the Merlin patch panel as ODU connectors in both Master and Slave
racks as shown;-
The ports are labelled 1 and 2 and in addition there are two pairs of "link"connectors to facilitate tidy wiring to and from arrays,
particularly where cables have been loomed together (see the chapter on cabling). A standard system would run the first U-Net
connection from Port 1 up to the first cabinet at the top of an array. Short link cables (or looms including audio) would daisy-
chain down between all cabinets in the array with a cable from port 2 in the final cabinet at the bottom of the array returning to
the rack. If there are other cabinets in the system, perhaps a side hang or a sub array, this cable should run to the first cabinet
of the next array however as you can imagine this would make for very messy wiring which is where the link connections are
used. If loomed cables are used to each array, the "return"network cable goes into one of the link connections and the
"send"cable for the next array goes into the other link connector. The return from the second array can either go straight to the
Merlin port 2 on the patch panel of even to the next pair of links if there is a third array. As you have introduced two connections
to the cable run between nodes the maximum cable run is now approximately 113metres however if you are using standard 35m
U-Net cables to each array the cable run is only 35 + 35 or 70metres from the last cabinet in the first array to the first cabinet in
the second array, well within limits. Even if you had a particularly long run to the main array and used the 75m U-Net cables, as
long as you use a 35m cable to the next array you are still within limits (just!).
This system makes for very straight forward and tidy wiring with all connections; network, audio and mains going back to the
rack so cable management is no more difficult than a conventional system, in fact given that for the majority of systems there is
likely to be only a single rack at side of stage the system is very neat and economical in terms of truck space and venue real-
estate.

Ethernet

The connection between PC and Merlin is by completely conventional Ethernet and uses standard, off the shelf Ethernet products
other than cabling. To maintain the rugged cable connectivity the same touring grade Cat 5e and ODU connectors are used as
for U-Net connections. The default Ethernet connection from the Lenovo PC is Wi-Fi directly to the Wi-Fi WAP connected to the
Master rack however it is advisable to run a cable connection out to Front of House particularly with Mk 1 Master racks that use
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