Free estimator
ZOE: how much Voice Alarm amplifier power does your building need?
ZOE (Zone Output Estimator) estimates indicative amplifier power per zone across a whole building from rough geometry. Pick a space type for each zone, sketch its areas, duplicate the zones that repeat, and ZOE returns loudspeaker counts and an indicative power figure you can send to a Voice Alarm manufacturer for a budget quotation. Everything runs in your browser. Nothing you enter is stored or sent anywhere unless you choose to send yourself the summary at the end.
ZOE is for the stage before a drawing exists: a facilities or estates manager scoping a replacement system, a surveyor pricing a building, or a consultant who needs a defensible first figure before the site survey. It answers one question for each zone: how much amplifier power, and roughly how many loudspeakers, this space needs to reach its minimum level above the noise it will have in use. Free, no email, no callback, just the number.
The tool
Some space types use ambient-noise figures inferred from the closest comparable space type, as no published value exists for them. They are marked provisional in the results, and ProAudium can confirm them with a measured site survey.
A starting point, not a limit: you can add, insert, duplicate, reorder or delete zones at any time.
Choosing a space type fills this zone with standard assumptions: its operational noise level, signal to noise ratio and minimum level. They are starting points, not measurements. You can adjust these values below for each zone, and every assumption used is listed with your results. The more of these assumptions you rely on unchanged, the further the estimate may sit from your actual project.
Advanced: your own noise level, signal to noise ratio or minimum level
Leave a field blank to use the space type's figure. A measured noise level from your site replaces the assumed one; your figures are labelled as yours in the results and the email.
How ZOE works out the figure
Each space type carries a set of starting assumptions: its operational noise level, the signal to noise ratio above it and the minimum level the broadcast should reach. ZOE turns those into a required sound level, works out the loudspeaker spacing and transformer tapping that reach it at the ceiling height you give, counts the loudspeakers for the area, adds spare amplifier capacity, and sums the zones. Every assumption used is listed under the result with the clause it comes from, so the figure can be checked rather than trusted. Where a space is louder than the assumptions suit, ZOE says so.
The assumptions are starting points, not measurements. The more of them you rely on unchanged, the further the estimate may sit from the project. What we assumed for each zone is printed with every estimate and in the manufacturer email.
Where a space is tall, reverberant or noisy, ZOE isn't the right tool for it, and a larger amplifier won't help either: more loudspeakers won't fix the room. A survey and an acoustic model will show what does: consultancy, acoustic modelling and specification.
What happens after the quotation
Once a budget figure becomes a system, it's worth looking after it as its own discipline rather than as a line in the fire alarm contract. BS 5839-8:2023 recommends servicing at intervals not exceeding six months (Clause 40.1) and, at the annual service, measuring every loudspeaker circuit's impedance and comparing it with the previous year's (Clause 40.2 i)). The loudspeaker count ZOE gives you is the number of things that will need testing. See what each of the three maintenance levels includes.