The most common question in commercial installation is not which speaker is best, but: how many do I need, and what goes in front of them? For small and medium spaces, both can be planned with surprising reliability — without measurement equipment, using four numbers and a handful of rules from practice.
How many speakers the room needs
These values apply to even background sound with wall mounting at a height of 2.2 to 2.5 m. For voice announcements only, one unit fewer is usually enough. Where the ambient noise level is high — an open kitchen, a sports bar, lots of glass and concrete — plan for one more.
| Room | Area | Speakers | Amplifiers |
|---|---|---|---|
| Office, small meeting room | up to 25 m² | 2 | 1× |
| Conference room, café, practice | 25–50 m² | 4 | 1× |
| Restaurant, retail unit | 50–90 m² | 6 | 2× |
| Large area, several zones | 90–130 m² | 8 | 2× |
What stands out is how little power is involved. A speaker with 88 dB sensitivity reaches almost 100 dB at one metre with 15 watts — while background music typically runs on one to two watts. Wattage is virtually never the bottleneck in this kind of system. Distribution is what matters: six quiet speakers beat two loud ones. Saving on quantity does not give you a quieter system, it gives you an uneven one — too loud at the front, unintelligible at the back.
Where the speakers belong
- Mounting height 2.2 to 2.5 m, clearly above head height, angled slightly downwards towards the seating or standing areas.
- Not directly in room corners. The two adjoining walls raise the bass in an uncontrolled way and make the sound muddy.
- With opposing placement, avoid aiming units exactly at each other on one axis, or audible interference builds up in the middle of the room.
- Cover bars, reception desks and walkways first — that is where people speak, and where a lack of intelligibility shows up first.
Amplifiers, channels and the timing problem
A 4-channel amplifier such as the Lyndahl AMP4X15BT drives up to four speakers, each on its own channel. Connecting fewer than four is no problem; open channels do not harm the unit.
From six speakers upwards you need two units — and this is where the most common mistake in practice occurs: two amplifiers mean two separate Bluetooth connections, and those do not run in sync. Pair a phone with one amplifier and connect the second separately, and you will hear a clear offset where the coverage overlaps. The fix is simple: feed both amplifiers via the AUX input from one shared source. A plain jack splitter will do. Mixed operation — one over Bluetooth, one over cable — does not work.
For the AUX path the usual rule applies: use well-shielded cables only. Cheap jack cables are by far the most common cause of hum and crackle in systems like these.
Wall or ceiling?
Both work, but not equally well everywhere. Wall speakers such as the Lyndahl SB242M need no ceiling cut-out and no suspended ceiling — they are screwed in place and aimed. That makes them the first choice in existing rooms, in rented units, with concrete ceilings, and anywhere sound is added later without opening the ceiling. Another advantage: the direction can still be corrected after mounting.
Ceiling speakers from the CS range are invisible in return and cover more evenly from above. They do require a suspended ceiling or sufficient cavity, and cannot be re-aimed once installed. How to plan cut-out and depth is covered in Planning in-ceiling speakers.
In practice the decision is usually dictated by the building: where there is a suspended ceiling, install into it. Where there is none, mount on the wall.
Where this system ends
The technology described here is low impedance, 4 to 8 ohms. That is the standard for small systems up to roughly eight speakers in one location. As soon as a system spans several floors, serves many rooms at once, or has to deliver emergency announcements, there is no way around 100-volt technology — there all speakers share one line and the power per unit is set with a transformer. That is a different product range and a different kind of planning.
Two more limits from practice: indoor compact speakers are not ball-impact resistant, so sports halls need an additional protective grille. And outdoor areas, terraces and wet rooms require an appropriate IP rating — indoor speakers will not survive a winter there.
Two things that get forgotten
The amplifier needs power at its installation point. A socket in the ceiling void or the technical cabinet belongs in the plan and in the hands of an electrician — added later, it is the most expensive item of the whole system. Also pull a shielded cable from the amplifier position to an accessible point while you are at it, in case a source is to be fed in via AUX later on.
And the commercial point: playing music in hospitality, retail and other publicly accessible spaces requires registration and licensing regardless of the equipment used. That does not concern the system, but it does concern the operator — and it should be settled before opening.
We are happy to help with a specific space: send a floor plan with room dimensions and intended use, and you will get back a proposal with quantities and amplifier configuration.
