The Siren Board

Hi all,

Does anyone know the peak frequencies of dual tone Alertronic controllers? Potentially also the start frequency.
Thanks.

Could not tell you the start frequency but they peak at 654 and 763.5

Thank you very much. Helps a ton!

I calculated that Alertronics such as Odegen, IA are 740 HZ. Dual tones are 780/680 HZ. I would assume that the start frequency is half of the peak frequency, therefore:

Alertronics such as Odegen, IA:
Start: 370
Peak: 740

Dual tone Alertronics:
Start: 390/340
Peak: 780/680

Ah, that's interesting, two different frequency sets. I'll try both and see which sounds more accurate. I'm also guessing the deep throaty sound comes from the drivers not the tone?

HX56 wrote: ↑

Mon Jul 26, 2021 12:14 pm

Ah, that's interesting, two different frequency sets. I'll try both and see which sounds more accurate. I'm also guessing the deep throaty sound comes from the drivers not the tone?

All the drivers do is reproduce the sound fed to it through the amplifiers (themselves fed by the tone generator) into whatever chamber the sound will emit from (a reentrant horn, a speaker chamber in a stereo, etc.). Far more goes into how a tone (or music or whatever) sounds than just the frequency. Horn/speaker resonance is one thing (think why different speakers sound, well, different) but, more importantly for tone generation, so is the shape of the wave. Go look it up. Siren tone generators are really nothing more than primitive simple synthesizers so many of the principles translate.

The community on social media and on YouTube seems to think the drivers do everything when in fact their role is just one part of a complex device.

I see, I guess the online idea is what got me thinking that way. I've seen how much is inside the cabinets so I guess you're right, if it's not needed why would it be in there? I believe Alertronics use either a square or pulse wave.

They actually use a triangle wave with varying tones for all electronic sirens (Except Whelen, which uses square)

SuperBanshee836335 wrote: ↑

Wed Jul 28, 2021 3:24 am

They actually use a triangle wave with varying tones for all electronic sirens (Except Whelen, which uses square)

For real? Wow. I always thought they would have used a pulse or square. Also surprised they use a triangle over sine, but oh well, it works. Guess you don't want to blow the drivers. Thanks for the help!

SuperBanshee836335 wrote: ↑

Wed Jul 28, 2021 3:24 am

They actually use a triangle wave with varying tones for all electronic sirens (Except Whelen, which uses square)

This is incorrect. It’s all square.