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8. Operational quality issues

Networking technologies introduce new audio quality issues that system designers and sound engineers have to be aware of in order to achieve a high audio quality. However, networking technologies also introduce new and exciting possibilities for system design - along with new quality issues that are not related to audio or sound, but to other fields such as costs, logistics and reliability. This chapter presents a selection of operational quality issues: network implications, Ethernet compliance, redundancy, and cable lengths. Similar to audio quality and sound quality, investors and rental customers can set requirements for the networked audio system to comply to operational quality requirements - with the system designers and sound engineers being responsible for compliance.

8.1 Network implications

In this white paper we propose the following basic definition of a network:

A network offers functional connections independently from a system’s physical connections.

This means that in a networked system, all connections in the network can be set up completely independently from the cabling. To connect a device to a network, it doesn’t matter to which physical connector the device is connected. The functional connections - in the case of networked audio systems all audio connections - are established through routing software.

Network hardware (networked audio devices, Ethernet switches, cables) can be connected physically in three topologies: daisy chain, ring and star. Some network protocols only work in daisy chain or ring topologies, and some work in all topologies - but in all cases, the way the devices in a network are connected within the topology does not affect the software controlled routing. In the networked audio field, examples of networks that require a ring topology are Optocore(*8A), Rocknet(*8B) and Ethersound(*8C). CobraNet(*8D) and Dante(*8E) support all topologies. For more detailed information on audio networks we refer to the white paper ‘an introduction to networked audio systems’ published on the Yamaha website(*8F).

The separation of physical cabling and functional connections in networked audio system has implications for the design and use of networked audio systems.

In the design process of a conventional audio system, functionality and physical cabling are always connected - a change in a system’s function requires a change in the system’s physical cabling and vice versa. When designing functionality, the designer is constrained by the physical cabling possibilities. And if changes to either the functional or physical design are required to be implemented afterwards, the one is always constrained by the other.

In the design process of a networked audio system, the two design jobs can be separated: the functional design can be done first - without physical cabling constraints, and then the physical design - possibly even by another design engineer. The only constraint for the functional design is to stay within the network’s data bandwidth - for networked audio systems usually the maximum number of channels for a single cable in the network, eg. 64 for EtherSound, 512 for Dante. Design changes afterwards can be implemented easily without changes to the cabling system - provided the system’s channel count stays within the available bandwidth. This saves design labour costs and increases the speed of the design process. In many cases it also increases the reliability of the design because the separation of the two jobs make the design process less complex.

Installation & set-up
For the installation or set-up of conventional audio systems, the cable installer needs to have a detailed knowledge of the system’s audio functions - as the way cables are connected affects the system’s functionality. This requires experienced staff and extensive quality management procedures to include not only the physical cabling but also the audio functionality.

With networked audio systems, the cable installer doesn’t need any knowledge on the system’s audio functions - so less experienced staff can be used, and quality management procedures don’t have to include the audio functionality - saving costs and set-up time.

>>8.2 Ethernet compliance

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