1. FEATURE ARTICLE
Alarming developments
29 October 2008
Chris Fitzsimmons examines some of the technical and product innovations
occurring in the world of EN 60849 compliant voice alarm systems. A different
approach to the legislation from The Netherlands is opening up and interesting
design opportunity.
Voice alarm has rapidly
gained traction in many applications as an alternative to traditional emergency sirens. Hybrid
public address and voice alarm systems take advantage of the need for standard audio
infrastructure for paging and public announcements as well as emergency messages.
However such emergency systems are subject to the European standard EN 60849 or
equivalent national standards and so delivering emergency messages over a standard public
address systems brings with it all the requirements of backup power supplies, redundant
amplification and line monitoring.
The need for such stringent performance regulation and redundancy has meant that
emergency systems have been relatively slow to take advantage of digital technologies,
however that adoption is now coming on apace with all of the major players employing
networking and IP-based technology in their systems.
The latest to join the IP party is TOA. Whilst the company has long been a market leader in
PA and VA it only now that it has a fully digital decentralised offering to rival the likes of
Bosch’s Praesidio or G+M’s APS systems.
SX—2000 is a fully network-enabled decentralised system for large installation projects such
as stadiums. It has already been employed at the Beijing Olympics and is due in Europe this
autumn.
The system is modular in nature, like many of its counterparts and consists of the System
Manager unit, sitting over a number of audio input and output boxes. It’s a matrix style
system with a total of 64 audio inputs and 128 outputs available. Rather than developing its
own audio protocol, TOA has elected to license the Cobranet digital audio system to connect
remote units. The system controller features full DSP functionality.

2. Also new from TOA is the VM 3000, this is a fully EN 60849 compliant upgrade to the
existing VM 2000 product, designed for smaller scale installations. At its most basic is a six
zone control box, with everything needed included. However you can expand to more zones
but adding a number of slave modules.
Bosch’s Praesideo has now been on the market for around five years and at its inception was
based on digital technology. In the intervening period the company has added hardware
modules and software functionality to continue to respond to customer needs. Like TOA,
Bosch takes a modular approach with a central control box governing a number of input and
output modules and amplifiers.
Product manager Martijn Van Overveld admits that the competition is now fierce: “There are
a lot of competitive systems on the market right now. I would say that how we differentiate
ourselves from the competition is more that the total package is better. Combining our
amplifiers, with the system controllers and our ceiling speakers makes for a much more
efficient installation.
The Praesideo system also uses a single cable for both power and signal within a rack.
Equipment is connected in a daisy chain arrangement with the bus running down from the
controller, through all the amps and then back-up the opposite side of the rack. This
immediately introduces redundancy into the system because information (and power) can be
distributed in either direction around the bus.
The way the Bosch system handles amplifier redundancy is also rather elegant. Bosch’s new
Plena basic amplifiers operate in such a way that if you have a rack of ten, an 11th amplifier
can act as the spare for the whole stack. Whilst other manufacturers include a redundant amp
in each box, this can start to become prohibitively expensive in very large-scale systems.
British manufacturer Baldwin Boxall’s Vigil 2 product has been in the market for almost 2
years. Sales Director Neil Jarvis feels that one of its distinguishing features is its engineering
provenance being a UK-manufactured system. It’s also designed to meet the requirements of
BS5839, which are more rigorous than EN60849.
The system’s main component is the BVRD2M system controller, each of which can run a
total of 96 zones. These units can be networked almost without limit making the system
highly scalable. The message playback unit can be used to serve a number of BVRD2M units,
either via direct input or over a dedicated digital audio network, allowing the system to be
either centrally served or arranged in a distributed fashion. The Baldwin Boxall network
controller is the EVA, which operates a bi-directional ring topology for increased system
robustness.
Vigil2 is also compatible with digital audio networking and DSP solutions such as Peavey’s
MediaMatrix. An example installation carried out by the DRV Group is Birmingham’s NEC
Arena in the UK. Here each exhibition hall is served by a self-sufficient BVRD2M controller
and a rack of amplifiers, and then each of the controllers is linked over a MediaMatrix
network.
Baldwin Boxall also produces its own control software package and a range of touch panels,
which the company can customise for a particular customer depending on its requirements.

3. In common with many of his competitors Jervis believes that the network is the most
important innovation in PA/VA systems at the moment: “The technical challenges of using IP
networking have been largely overcome now. The main differences between systems now
come down to how they use the network. We prefer to run our protocol on a dedicated
network. It uses a fair amount of bandwidth and on a shared network there is more risk of
interference or signal delays. Even a couple of milliseconds can lead to messages being
played out of sync in different zones, making them unintelligible.” This is of course totally
unacceptable in a life safety application.
One manufacturer happy to operate over a shared network is Swiss outfit G+M Elektronik.
Michael Roffler, the company’s R&D manager explained why this is possible. “Our protocol
only uses 8kb/s per audio channel as the audio is highly compressed.” Whatever network the
system uses it also monitors its status at regular intervals, waiting for replies from all nodes.
At one installation at a university in Switzerland, G+M installed separate racks in each of 28
buildings, before linking them over the campus’s existing network infrastructure. The
university, along with a lot of other clients these days, were keen to save on personnel costs so
the system was monitored from a central control room. Ethernet networks can be a highly
robust solution since often there are a number of possible routes between points. Even if one
fails, there is the possibility for control and status signals to find another way. However in the
event of a total failure, each of the racks is totally self-sufficient and can function whilst cut
off.
G+M’s most successful VA product is the modular APS system. Unlike the Bosch and TOA
systems it’s not a matrix-based system. “Instead of using a lot of different audio buses, we use
a priority system which requires less total channels,” said Roffler.
Another Swiss player in the market is Ateis. Its latest EN 60849 compliant product is the
DIVA – a single box compliant voice alarm system. Albert Vanderhout, European Sales
Manager for the company described its innovative approach to amplifier redundancy. “DIVA
contains two amplifiers. One is a dedicated public address and alarm amplifier and the second
is used for background music instead of sitting idle. If the backup is needed, the BGM is then
disabled and the amp runs as the spare VA unit.”
The range is available with power outputs up to 480W. To compliment the DIVA unit, Ateis
also produces two ranges of amplifiers – the DPA series based on Class D technology and the
SPA range of Class AB devices. DIVA itself offers 16 monitored outputs, with two channels
over 8 zones for redundancy.
Ateis are also working on IP-based solutions. Using its existing IDA switches, in combination
with its LAP network enabled amplifiers customers can now build redundant audio networks
over the company’s AteisNet protocol. The company is currently working on IDA 8 a big
brother to IDA 4. It will operate 8 channels per unit instead of the current four and is
expandable to create a matrix of up to 300x300 channels.
Digital networking solutions are excellent ways of linking distributed racks of amplifiers with
each other or a control system, however from amplifier to ceiling speaker is still generally
covered by good old fashioned 100v lines. For EN 60849 these speaker runs need to be made
of toughened cable. However, in Holland the authorities have now allowed an alternative
solution. If the speaker runs are arranged in continuous loop instead of a straight line then the

4. requirement for toughened cable is revoked. This is similar to the legislative requirement for
loops of fire detection units. Since standard cable is about 10% of the cost of a fireproof
solution this could result in significant cost savings.
G+M are among the companies who have already developed products to address this solution.
Their APS-178 Loop device sits on the speaker loop and is attached to the amplifier. It
monitors the entire line, and in normal operation is sends the audio signal one way around,
treating it like a conventional cable run. If it detects a break in the line the device splits the
audio signal and sends it in both directions, avoiding the break. Other devices are placed in
each audio zone to detect and isolate short circuits.
If adopted by countries outside The Netherlands, this technical innovation could represent a
significant revolution in emergency system design.