The Holy Grail of distributed audio; unlimited zones and unlimited
sources, cost effectively. That milestone will be achieved, and soon,
through the combination of digital amplification and IP based
distribution systems. There are systems available today that use one or
both of these technologies, such as Oxmoor's Zon system and Netlinks'
Netstreams product line. The trend will only continue to grow.
The
beauty of this approach is that digital music is data, and, as such,
can be distributed easily via an Ethernet network. The traditional
concept of zones virtually disappears, as each amplifier on the network
gets a unique IP address, enabling an audio stream to be routed to it.
When combined with a digital music server, the number of zones is
limited only by the ability of the server to serve independent audio
streams.
The advent of cost effective digital amplification, produced by
companies such as D2 Audio and Flying Mole, allows a small, highly
efficient audio amplifier to be located close to the speakers, either in
the room or mounted in an electrical box. The logical evolution of this
approach is to collocate amplifier with the speaker, creating an active
speaker. Additional benefits are realized by incorporating the speaker
as part of the circuit. This enables the designer to engineer the
speaker and amplifier circuits for optimum performance as a system.
Low
powered designs of this nature could take advantage of power over
Ethernet (POE), simplifying system wiring by allowing a single CAT-5
cable to be run from the router to the speaker. This would not supply a
large amount of power (about 15 watts) due to the constraints of the
24ga conductors used in CAT-5. However, the efficiencies gained by an
integrated speaker / amplifier design would mitigate this concern to
some degree. This type of system is sufficient for background music
applications in many residential environments.
Higher power
systems can use the existing speaker wire, in the case of a
conventionally wired system, to carry power. It can / does use the
existing control cable, since many systems have been wired with CAT-5 to
the volume control location, for the data.
The bandwidth of a
traditional 10/100 network allow, for all practical purposes, an
unlimited number of zones and sources in a residential environment.
Partly because of this, Audio Over Ethernet has been used successfully
in the commercial audio and sound reinforcement world for a number of
years now. Cobranet, from Cirrus Logic is the most popular commercial
AOE system used today. Another popular system is available from
Digigram. These systems both use the MAC layer of Ethernet and are not
actually using IP for transmission. asdasdddddddddd
For both residential and commercial applications another
primary advantage of using Ethernet is the ability to use the medium for
transporting both audio and control signals down the same wire. This
increases flexibility and reduces cost for both installation and
material.
