Audio networking - everyone’s doing it now, aren’t they? The entry cost is now under €50 for some audio networking software and a network switch. But how often do we consider the risks and requirements before jumping in?
Topic 1: Mobile or installed?
Is your network going to stay in one place for all its life? Most network switches and cables are designed to stay still and gather dust. Or will it be moving daily, weekly, monthly? In which case you’ll need more durable cables and connectors, racks and cases. Use the range of rugged switches available with Neutrik EtherCON and OpticalCON connections. Damaged plastic RJ-45 plugs cause a vast amount of lost data, time and frustration - you don’t want to let a €0.50 item ruin a €500k show. Protect your precious data and don’t treat a 96-channel stagebox like you would a hotel bedroom’s internet connection! How about the switches themselves? I’ve seen some shake their screws loose after a few road trips. Just because it has rack ears doesn’t mean it’s fit for a flight case! If you’re touring, buy a switch from a company that knows all about touring.
Topic 2: Fixed or Changeable?
Is your network like ‘set and forget’? Then it won’t be important how difficult it will be to expand in the future. On the other hand, some networks might need to be altered weekly or daily. In that case, you need switches with spare ports, spare bandwidth and they must be easy to re-program. Perhaps you’ll need an extra VLAN or Trunk? Switches with front-panel configuring could be worth their weight in gold for the time they save. Regarding bandwidth, four Dante audio channels at 48kHz, 24-bit use up around 8Mbps. That allows 500 audio channels in and out of each 1GB port. But remember to count the channels twice if one stage-box transmits to two consoles, for example.
Topic 3: Security.
You need to balance accessibility with security. If the network is fixed and installed, security can be tighter to stop unwanted users and block rogue equipment. However, if the network is mobile and changeable, quick accessibility is important, so security should be looser. However, one potential Achilles heel is Wi-Fi. The sound engineers and musicians might need it to control the audio equipment, but the airwaves can become congested when the audience arrives. One tip is to hide the Wi-Fi SSID name. Then nobody can find it unless you tell them! One more thing: will your network switch protect you from the classic rookie mistake? Plug both ends of the same cable into one switch. Oops. Yes, halt a network with a €1 cable! Make sure your switch has loop protection: you will be thankful for it on untold occasions.
Topic 4: Clock Sync.
Consider a classical orchestra: If a musician can’t see the conductor, how can they keep in time with the others? In an audio network, there will be one timekeeper for all other devices to follow. An audio network such as Dante will be more effective at keeping all devices in time than a spiders web of long BNC cables. If a device in the network needs to synchronise to an external source, make sure that device is the Master Clock for the audio network. Then allow the network to distribute the clock. Use software such as Dante Controller to reveal any sync problems quickly. It is a good idea to select one or two ‘Preferred Master’ devices: choose ones that are the first to power on each morning and stay on all day.
Topic 5: Design Experience.
Don’t out-design yourself. Don’t create something you can’t support or trouble-shoot. Go easy on the switch programming until you’re confident of being able to fix any unforeseen problems. Some switches have presets, making it easy to use some quite advanced features. Others take time to learn. Keep the audio network separate from all other data until you get familiar with VLANs, Trunks and Link Aggregation. Later you can discover Spanning-Tree Protocol, QoS and IGMP Snooping… Until then, don’t be afraid to keep it simple. In addition, document everything: keep drawings of the network layout and all the cable connections. Note all the IP addresses and subnets used. Document it in such a way that an educated stranger could rebuild the network exactly as you did. Take time to save time.
If you would like to go deeper into output system design for sound reinforcement, check out the further reading materials below, or attend one of our YCATS Yamaha Commercial Audio Seminars. You can find the European schedule at www.yamahaproaudio.com/training
Next week’s micro tutorial will focus in on clocking in networked audio systems.
Dante network design guide