Rane NM 84, Operator'S Manual

Manual-11

for listeners in the initial, center seats may not find this delay

acceptable. Assuming that no propagation delay is added

through other digital signal processing or a digital console

(this may be the case), the additional network delay of 6.5175

feet – assuming NM 84s on and off the network – may place

the arrival time of the direct sound versus the acoustic arrival

outside the Haas effect time. This would make the propagation

delay unacceptable for this application. If you’re implement-

ing a mic snake type of application and are including the

monitor audio for stage members on the network, be sure to

not exceed an acceptable delay time; a delay time not much

more than 10 milliseconds (or hopefully less) is probably

acceptable for monitor applications. Decide for yourself.

That being said, there are upcoming technologies (i.e.,

vaporware) that may cut this network propagation time in half

or more. But, like most vaporware, we’d have to kill you after

we told you about it. So, when this really becomes available,

we’ll let you know. This way, we won’t have to kill you now.

Cables. Unlike simpler analog audio cable, choosing and

installing CAT 5 network cable and connectors can be

challenging and deceiving given that 100 megahertz data is

being transported. Plus, the connector termination is not

intuitively obvious; get it wrong and you’ll spend hours

blaming equipment when it’s the cables all along. (I know this

because I’ve spent a full day and a half suspecting equipment

when the cables were to blame. And yes, the cables had tested

fine with a continuity tester, but a continuity tester is nowhere

near good enough a test for the required 100 megahertz data

we’re talking about here.) This cable stuff requires special

attention beyond that normally paid by us audio guys who are

now trying to implement these newfangled audio networks.

Do yourself a favor and visit Peak Audio’s website where

they have a great primer on Network Cabling.

http://www.peakaudio.com/cobranet/network_cabling.htm.

Finding or training people to deal with network cable and

network troubleshooting is a worthwhile investment if your

future includes networked audio systems.

Remember that the network hardware devices chosen for

your network go hand in hand with the Bundles required to

deliver audio for a given application. Multicast networks/

Bundles can be transported over repeater hubs or over

switches; Unicast networks/Bundles require using switches.

You cannot transport unicast data over repeater hubs.

Although the Network Hardware (Table 2) and the

CobraNet Bundle (Table 1) are similar, they are listed sepa-

rately since, for example, multicast data can be transmitted

over repeater hubs or switches. Thus listing them separately

allows you to determine which approach is best for your given

application.

When observing the indicators on switch ports for

CobraNet devices, Rane NM devices appear as full duplex

devices. (“Rave” devices – available from our friends at QSC

Audio – appear as half duplex; this may change however, so

check with QSC.)

A Few Words About Networks

The opening primer in the Quick Start about designing a

network makes it sound so easy – and it is, relatively – but it’s

like using three sentences to say design a sound system for a

building. Like many technologies, there is always something

new to learn. Networks and Ethernet may be new to audio

folks, but they’re old news to computer types. Here are a few

good places on the Internet for more information on these

subjects:

   Rane’s main “network help” links page:

www.rane.com/ethernet.html

   Network Design:

www.peakaudio.com/CobraNet/Network_Design.html

The folks at Peak Audio are, obviously, an invaluable

resource for CobraNet information. Do not underestimate

their interest in the success of your designs or their willing-

ness to help with network design or the myriad questions

that arise.

   John’s Closet - A down-to-earth set of networking how-

to’s: www.johnscloset.net

   Ethernet Tutorial - A wonderful tutorial in plain English

from Lantronix:

www.lantronix.com/training/tutorials

   Informit.com - Free online books about programming

include lots of Web stuff

   Network Design Tutorials & Other Resources - An indus-

trial-strength link list of networking topics:

www.alaska.net/~research/Net/nwpages.htm

   Ethernet Information - Network Basics / Cabling:

www.windowsnetworking.com/j_helmig/basics.htm