Fitted loads of Novaguard 4Q's - the battery is a 1.2 A/h 12 Volt and the four piezos run off only that internal battery - which used to be very handy - you wired it and set it up as a SAB but as it drew no bell current (only strobe current - the strobe later became an equally bright but low power consumption version later on) from the panel it was like an SCB - so you could fit more than one 4Q without any real current consumption issue from multiple bells needing auxiliary PSU's in the days of control panels having at most a 1 Amp PSU that was very useful for big multi bell systems - now there are a lot more panels with a 2 Amp PSU output and lots of fully monitored auxiliary PSU's so in that one narrow way the 4Q is no longer needed to avoid fitting Aux. PSU and the hassle (back then) of a second battery to monitor non-remotely.
But ye-gods the 4Q is loud and reliable - as long as you change the battery - ideally every five years (fully charge the replacement battery first - the 4Q is not the place to overcome the sulphation of an old stored battery - its fine once the battery is in use on float charge) and remember that the masterblaster needs a 240 volt mains power connection - if that goes missing no masterblaster siren - but the 4Q runs off its internal battery no matter what!
You can adjust the 4Q siren tone using a potentiometer next to the terminal block to achieve a nauseating toothache inducing racket - it's the kind of noise that reaches the parts that a masterblaster just can't quite reach!
So of course the Loonies making decisions at Risco discontinued the Gardiner Technology 4Q a unique product - once Risco got British Gas to buy control panels from them it went straight to Risco's head.
There is an Israel only Risco sounder that is even louder - something like 130dB RMS at 3 Meters (4Q was 123dB RMS at 1 Meter) but it looks nothing like a UK sounder and Risco won't bring it to the UK - the Israeli one is in one of my old Risco paper catalogues (if I come across it will scan it and upload - not promising have to find it first) if memory serves the Israeli one can be used with any panel but can also establish an intelligent link with a ProSys Bus to remotely monitor and test the battery and make current measurements etc. - like Risco's NovaguardActive link between multiple independently addressable and separately identifiable bells back to one panel for remote interrogation of battery status etc. (naturally Risco have cut that down as well to only two addressable bells on Nov.Active nowadays) but the Israel only one is on steroids compared to a UK Nov.Active - which I admit we do use if it is a Risco bell and panel.
The Israeli one has two interesting features it uses a speaker (not a piezo) as its sounder and it has a radar field which you can adjust (or switch off altogether) so if anyone comes within about a meter of the Israeli one on the wall it goes off before it can be touched - an intriguing concept - a nightmare for nuisance alarms if mounted too accessibly but if carefully sited the radar field could be useful - of course Risco won't bring it to UK.
Risco? With their attitude nowadays more like RICO - Racketeer Influenced and Corrupt Organizations Act (Organized Crime Law in USA) but I digress.......
There was a vertical type bell (non Risco) which had two giant piezos (about 5" across) that could produce something like 129dB (iirc) at 1 meter but that was only a peak measurement - (when we came across one it was nowhere near as loud as a 4Q) the 4Q, masterblaster and Israeli Risco one all had measurements quoted as RMS.
Anyone else want to chime in with the most powerful bells / sirens? They are good free advertising for an alarm company!