The NEC is the UK’s number-one venue for shows, exhibitions, meetings, and events. Officially opened in 1976, the NEC has grown significantly in size and reputation. Today, the NEC boasts 18 exhibition halls, a performance arena, 32 conference suites and a host of additional outdoor spaces. These flexible areas host over 2.3 million guests and over 500 events every year and are included as one of the venues for 2022’s Commonwealth games.

B L Acoustics have over 30 years of expertise in life safety systems and were gratified to equip the venue with a leading range of new Public Address and Voice Alarm equipment. Our mission to replace the site’s outdated system began in 2019 with our team completing design specifications, site surveys and design engineering/reviews.

Technical Overview
The existing PAVA system at the NEC was distributed across the site with equipment operating in twelve locations, all interconnected by a fibre cable network, with most areas equipped with a local microphone used for making announcements. The existing system operated using a combination of four sets of apparatus, three of which were at the end of their design life, but all critical to the operation of the PA system and, therefore, the use of the building. The outdated control system and Cobranet devices located in a central point made up the routing system for the entire site. As such, it was necessary to upgrade the two elements as a single package.

With a view to enabling future upgrade works, we suggested an initial upgrade phase (Phase 1 of 3) that would consist of the following:
– Replacement of the GUI control points
– Replacement of media matrix audio routing
– Implementation of temporary serial servers at remote racks (allowing decommissioning of the serial bridges)

The replacement audio routing equipment, as part of this initial phase, would be physically located in a central location but would allow us to move to a distributed architecture over the course of the remaining phases.

Project Plan & Installation Phases

Phase 1 would involve the installation of the temporary serial servers which would not affect the operation of the existing equipment. The security user GUI and the administrator GUIs would be installed alongside the existing panels.

Phase 2 would see the installation of the ASL Vipedia’s into a temporary central location, which again would have no impact on the existing system. Inputs to the Vipedia system would be paralleled from the audio connections to the media matrix units. The media matrix unit outputs would be paralleled to wiring looms ready to connect to the Vipedia’s. Testing of the routing system would be completed alongside the existing system using the same inputs via the new control system and GUIs. This parallel method of operation meant the new system could be changed over without any loss of operation of the system and allowed the site to operate normally.

Phase 3 would involve the relocation of each of the Vipedia units to remote locations where they would be connected to the IP network switches as well as the secure fibre loop.  At this point, the audio distribution and architecture were changed and operating across the new equipment, but feeding the existing amplification

Phase 4 involved a series of rack upgrades across each rack location, replacing the existing amplification with compatible ASL V2000 amplification and creating a harmonized EN54 voice alarm solution.

System Description

The new voice alarm system was designed to be fully monitored and compliant across the 12 equipment locations on site. The distributed system was connected via a newly installed closed fibre loop network used only for the PAVA system.  The system comprises the ASL Vipedia range of equipment and associated ASL V2000 amplification, with each of the six V2000 chassis’ individually battery backed by 24V stacks mounted in the base of the racks.

Along with the central equipment, each location was fitted with a new local microphone—three new security microphones with touchscreen controllers were also installed.

The existing organiser panels in each hall were retained and reused, which provided inputs for background music and existing single-zone paging microphones. This routing could be dynamically changed using the admin control PC in the central location. A unique solution for a voice alarm system made possible by specially designed software by our in-house engineers.

Emergency messages were primarily stored in the audio router but were also stored and played locally in each remote audio router. The emergency and non-emergency messages could be manually triggered from the touchscreen control panels.

The system also featured an additional message player for storing and playing back other non-emergency messages. The user can load pre-recorded messages to this device or record directly from one of the desk microphones. Messages could also be scheduled to broadcast automatically to any configuration of zones.

In the event of a touchscreen failure, the ASL MPS10 desk microphone could be used independently. Grouped zone buttons on the microphone base provide backup functionality in an emergency.

The existing 100v loudspeaker network cabling was reused in all areas, with existing loudspeakers also retained.  Excluded from this was the Skywalk, whose loudspeakers were upgraded with higher performance EN54 units, so music could be broadcast to the area, something the existing loudspeakers were not suitable for.

Fault monitoring was governed by each audio router; a display on the front of each unit showed the status of the local equipment and an overview of the faults across the network. This information was also logged on the aforementioned admin PC.

The admin PC is used to determine the routing of background music and the organiser’s microphones based on the requirements of the venue and the events that are in place. It also serves as a secondary fault display and system logger and manages the messages available to the user interfaces.

Organiser Microphones

Existing panels located in specified areas across the site provide the facility (individually) for multiple microphone(s) to be plugged in. Specially designed hardware interfacing was developed to allow audio and control to be implemented over the limited existing single-pair cabling.

Background Music

These existing panels can also facilitate the addition of a background music source. The audio pairs were wired back to the rack and directly through to the inputs of the Vipedia. Each BGM input is routed based on the routing made by the admin PC.

Installation Challenges

Changeover works were set to begin in 2020; however, these came to a grinding halt upon the outbreak of the COVID-19 virus. The NEC became a vast new temporary field hospital accommodating 500 beds in April 2020. The venue would not be available for public or work access until 2021.
Now, the NEC has returned to regular operations, and installation has been completed by BLA. The new system is functioning as expected.

As incumbent maintainers and installers of the PAVA Systems at the ICC Birmingham, BL Acoustics were engaged to further upgrade the Voice Alarm systems for the newly refurbished Symphony Hall.

The specification required high-performance Music Routing for the Performance Spaces and Bars by utilising the existing sound systems where possible.

Music was routed via the Bosch Voice Alarm system using Symetrix AV Processing Controllers.

For the main Performance Space, we installed four HK Audio VORTIS 2 EN54 rated Loudspeakers providing a powerful & superb quality sound in combination with the Bosch Praesideo Voice Alarm Amplification.

Fourteen music inputs were distributed throughout Symphony Hall providing a great deal of plug and play flexibility with the Symetrix System routing any input to any output.

Input panels were constructed using the single gang MK Edge Brushed stainless panels as the standard. We would implement the use of two types of panels; one would have a single XLR input and the other a 3.5mm mini jack input.

Flexible Control

The Symetrix ARC-3 Control Panel provided simple control of each input panel/music source to multiple zones throughout the Symphony Hall Foyers and Performance Spaces.

Design Verification & Modelling

The expansion included the fitting of new bars in each of the lobby areas on Levels 3, 4, 5 and 5A, a new performance space and 2 hospitality rooms on level 5A.

As part of the project, we were commissioned to design and install voice alarm coverage to the acoustically unique space, specifically the performance area with its high open ceilings and full length glass exterior wall which presented significant challenges to intelligibility. Being integrated with the Voice Alarm system, the project specification necessitated the use of EN54 approved loudspeakers only.

Before we could commence physical works, Computer Simulated Modelling of the prime areas for new coverage needed to be carried out to give evidence of design and to plan the equipment and cabling requirements. A computer model (Catt Acoustic 9) was used to create the three-dimensional environment which was then compared in performance to the specified requirements.


The specification gave a target of band ‘G’ 0.48 STI or better for 80% of the area exceeding 85dBA.


Our model implemented surfaces that were approximated to the surface types used in the building. These would provide prolonged activity for sound in terms of reverberation. We distributed the reflective and absorptive surfaces accordingly and checked the reverberation levels were in line with what would be expected for the space.

               The Model

Our Catt model was a complete model of all areas. This enabled us to model a large number of options, should they be required. The model was run several times to see the most optimum position and direction of the speakers.


               Proposed System Performance

As stated in the specification, the system was expected to meet band G in 80% of the spaces. The most acoustically challenging space, as afore mentioned, was the performance area. Here, we specified 4 high power cabinet speakers capable of delivering the sound pressure levels and performance required to give clear coverage across the atrium.

For the Hard of Hearing

The Performance Space on Level 4 was fitted with a large 16m x 12m Seven Segment Induction Loop powered by UNIVOX Audio Systems. This was installed beneath the oak floor so as to be undetectable. An audio feed was provided to the loop from the PAVA rack BL Acoustics were installing in Hall 2. This would enable both audios from the Performance Space systems and from the Emergency PAVA to be transmitted onto the loop.


The installation exceeded the clients’ expectations and offered a massive cost saving by utilising much of the already existing amplification and loudspeakers.