In a mall, office tower or retail centre, public address systems do daily work that visitors only notice when it goes wrong: background music (BGM) at a comfortable level, clear paging for security and management, and scheduled announcements at opening and closing. Whether a system works is decided long before supply, in zoning, loudspeaker selection, amplifier sizing and the interface with the fire alarm.
This guide walks through the design basics of a commercial public address (PA) and background music system. It sits within AZEIDK’s low current systems solutions, which include public address paging in their scope.
Key takeaways
- A commercial PA system carries background music and everyday paging. Evacuation messages belong to a voice alarm system built with equipment approved for that function.
- Zoning follows use, ambient noise and operating hours, and should follow fire zones if the system will be muted by zone or later combined with voice alarm.
- A 100V line lets dozens of loudspeakers share one cable per zone, with each speaker’s power set by its transformer taps.
- Amplifier size equals the sum of the selected taps plus a reserve, and the load must stay within the amplifier’s rating.
- On a fire alarm, music and routine paging should stop automatically and alarm functions should take priority, as set in the approved cause and effect matrix. Test this during commissioning.
In this article
- What public address systems do in a commercial building
- Zoning the system
- Loudspeaker types and where to use them
- 100V line systems and speaker taps
- Ceiling speaker layout and spacing
- Amplifier sizing
- Analogue and network (IP) systems
- Fire alarm interface: muting and priority
- Common mistakes in commercial sound systems
- Public address systems from AZEIDK
- Frequently asked questions
- Conclusion
What public address systems do in a commercial building
A commercial sound system combines three operating functions: background music in malls, shops and restaurants; live paging from a management desk or security room to one or more zones; and recorded or scheduled messages such as closing times and car park notices. It usually comprises audio sources, paging microphones, a zone routing and control unit, amplifiers, loudspeakers, and cabling and mounting accessories.
This is not the same as a voice alarm (VA) system. Voice alarm broadcasts emergency messages as part of the fire alarm system. It is designed to standards such as EN 54-16 (control and indicating equipment) and EN 54-24 (loudspeakers), and it falls under the Saudi Fire Protection Code (SBC 801) and Civil Defense approval. A standard commercial sound system does not become a voice alarm system just because it is wired to the fire alarm panel. For the life-safety side, see our article on voice evacuation systems; this article covers the commercial and operational side.
Zoning the system
A zone is a group of loudspeakers fed from one line and controlled together for source and level. Good zoning lets security page the car park without interrupting the food court, or turn music down in offices while keeping it in the malls. The main criteria:
- Use: public areas differ from back-of-house, offices and stores.
- Ambient noise: food courts and car parks need higher levels than quiet corridors.
- Operating schedule: areas with different hours should be separate so they can be scheduled independently.
- Fire zones: if music will be muted by zone, or the system may later be combined with voice alarm, align audio zones with fire zones.
- Length and load: each zone has a practical limit on speaker count, cable length and amplifier power.
| Zone (shopping mall example) | Typical content | Design notes |
|---|---|---|
| Main malls and corridors | Background music and general paging | Ceilings may be high; regular ceiling speaker layout |
| Food court | Music and paging | High ambient noise; denser layout or higher taps |
| Car parks and external entrances | Security paging and notices | Weatherproof horn speakers with long throw |
| Management offices | Internal paging, low or no music | Local volume control where needed |
| Service areas and stores | Operational paging | Wall or horn speakers depending on height and noise |
Loudspeaker types and where to use them
- Ceiling speakers: the default for suspended ceilings in corridors, shops and offices, giving even coverage when spaced correctly.
- Wall or cabinet speakers: for areas without a suspended ceiling, such as service corridors and meeting rooms.
- Column speakers: direct sound horizontally in large, tall spaces and reduce reflections.
- Horn speakers: for car parks, open yards and noisy areas; they need suitable dust and water protection.
- Pendant speakers: for open, high ceilings in showrooms.
Before approval, check the datasheet for rated power and transformer taps, sensitivity (dB at 1 W/1 m), maximum SPL, frequency response, coverage angle and ingress protection. Loudspeaker characteristics are measured under the IEC 60268 series, whose Part 5 covers loudspeakers.
One example from the range: the Hikvision DS-QAZ1307G1T-E outdoor network horn speaker, with 7 W rated power, 110 dB sensitivity, 121 dB maximum SPL, 300 Hz–13 kHz response, 70° × 100° coverage, PoE power to IEEE 802.3at, SIP support, and IP67/IK10 protection. The Hikvision DS-QAZ1203G1-BE ceiling speaker is also available.
100V line systems and speaker taps
Connect twenty 8-ohm speakers in parallel to a standard amplifier and the total impedance drops to 0.4 ohm, enough to trip most amplifiers’ short-circuit protection. That is why BGM and paging systems use constant-voltage lines: the amplifier delivers a nominal 100 V at full power, and each speaker has a small transformer that raises its impedance and sets the power it draws. European practice uses 100V and the US market 70V; the project specification decides which applies.
Transformer taps select the speaker’s power, for example 6, 3 or 1.5 W. Each halving of power is roughly 3 dB in level. Line load impedance follows Z = V² ÷ P, so a 100V line carrying 90 W presents about 111 ohms. Speaker transformers also add insertion loss, which one manufacturer’s guide puts at 1 to 2 dB; allow for it when estimating levels.
Ceiling speaker layout and spacing
Spacing depends on ceiling height (H), listener ear height (L) and the speaker’s coverage angle. Design guides use a practical relation: spacing = (H − L) × a factor set by coverage angle and layout pattern. Ear height is about 1.5 m standing and about 1 m seated. For a speaker with 120° coverage the factors are:
| Layout pattern | Factor (120° coverage) | Example: 3 m ceiling, standing listener | Best for |
|---|---|---|---|
| Edge to edge | 3.46 | about 5.2 m | Low-level background music, tight budgets |
| Minimum overlap | 2.45 | about 3.7 m | Paging that must be clearly understood |
| Centre to centre | 1.73 | about 2.6 m | Very even coverage, listeners everywhere |
The factors change with the coverage angle on the datasheet; larger-cone speakers often have narrower coverage and suit higher ceilings. In reverberant spaces, level alone is not enough. Speech intelligibility is measured with the speech transmission index (STI) under IEC 60268-16 (2020 edition), which sets out measurement and prediction methods and lists typical application values in an annex, without setting binding pass criteria.
Amplifier sizing
- Choose the tap for each speaker based on the level needed in its zone.
- Add up the tap settings for each zone or amplifier output.
- Add a reserve. One manufacturer’s guide suggests 10%; the project specification may require more for future expansion.
- Select an amplifier whose rated power is at least the result. Check the rating on the datasheet; amplifier characteristics are measured under IEC 60268-3.
- Check cable length and cross-section so that a noticeable share of power is not lost as heat, especially on distant zones.
Example: a food court with 30 ceiling speakers on the 3 W tap draws 90 W. With a 10% reserve that is about 99 W, so a 120 W output would be a reasonable choice. Do not add speakers to the same output later without recalculating: extra load lowers the impedance below what the amplifier can drive.
Analogue and network (IP) systems
A conventional system uses central amplifiers and a 100V line per zone. Network systems carry audio over the data network to network speakers or amplifiers. Speakers are usually powered by PoE from the switch, zones and schedules are managed from central software, and protocols such as SIP link the system to telephony. Options in this direction include our public address and audio systems range, among them a 40 W single-zone network amplifier.
The choice depends on project size, existing network infrastructure, zone count and future expansion. The two can be combined: 100V lines for large zones and network units for scattered or outdoor locations.
Fire alarm interface: muting and priority
According to an article in Consulting-Specifying Engineer based on NFPA 72, in combination systems, where a fire alarm shares components with non-fire systems, fire alarm functions take priority over non-fire functions. The same principle applies in practice to public address systems: during an alarm, music and routine paging must not mask sounders or evacuation messages. There are two usual approaches:
- A separate commercial PA system: the fire alarm panel provides a relay output to the mute or priority input on the controller or amplifier, stopping broadcasts building-wide or in the zones defined in the cause and effect matrix.
- A combined PA/VA system: equipment approved for voice alarm carries music and daily paging, with programmed priority for emergency messages. For example, Context Plus AVAC amplifiers (VA403 and VA402) have three balanced inputs for the emergency microphone, general paging and background music.
Either way, the mute signal path should be shown on the drawings and physically tested at commissioning and handover. A common priority order is emergency messages, then live paging, then scheduled announcements, then music. Coordinating the fire alarm panel and sound system falls under our programming and systems integration service.
Common mistakes in commercial sound systems
- Placing speakers by count rather than by ceiling height and coverage angle, leaving dead spots and loud spots.
- One zone for a whole building, so nothing can be paged or adjusted locally.
- Adding speakers to an existing line without recalculating amplifier load.
- Setting every speaker to the highest tap and turning the amplifier down, instead of balancing taps by zone.
- No link between the sound system and the fire alarm panel, so music keeps playing during an alarm.
- Relying on a commercial PA system for evacuation messages without equipment approved for that function.
- Ignoring ingress protection for speakers in car parks and open yards.
Public address systems from AZEIDK
AZEIDK supplies and installs public address and audio systems as part of its low current solutions, including loudspeakers, microphones, amplifiers, control units, zone distribution and installation accessories, from brands including DSPPA, Bosch and Hikvision to suit project requirements. Work starts with a site survey and the client’s requirements to set speaker layout, coverage areas, sound levels, ceiling type and integration with other systems. For commercial applications, see our malls and commercial buildings page.
Frequently asked questions
What is the difference between a PA system and a voice alarm system?
A PA system handles music and everyday paging. A voice alarm system is part of life safety, built with approved equipment such as EN 54-16 and EN 54-24, and subject to Civil Defense approval. The two can be combined if the equipment is approved for voice alarm and emergency priority is programmed.
Should I choose a 100V system or a network IP system?
100V suits large zones with many speakers on central amplifiers. Network systems suit scattered locations and projects with strong network infrastructure. One project can use both.
How do I size the amplifier?
Add up the selected taps of all speakers on the output, add a reserve, and choose an amplifier rated at least for the result.
Must background music be muted on a fire alarm?
Yes, in normal engineering practice. Music and routine paging must not mask alarm signals or evacuation messages. A signal from the fire alarm panel to the mute or priority input does this, and it should be tested at commissioning.
How many ceiling speakers does an area need?
It depends on ceiling height, listener height, the speaker’s coverage angle and the layout pattern. Work out the spacing first, then lay the speakers out on the drawing.
Conclusion
A good commercial sound system is the result of linked decisions: zones based on use and fire zones, speakers chosen for coverage and spaced by calculation, balanced taps, amplifiers with enough reserve, and a tested fire alarm interface. Where evacuation messages are required, treat that part as a separate life-safety system in its standards and approvals.
Planning a PA and background music system for a mall or commercial building? Send us the drawings, ceiling types and space uses, and we will propose zoning, speakers, amplifiers and the fire alarm interface. Talk to the AZEIDK team
