ATI Junk at NAS Pensacola

[jshelby861]

This past Friday, we went to NAS for the air show, and while on post we noticed multiple ATI Sirens along with the 2001 sirens
strange why have a decent siren like the 2001 and then put up junk like the ATI? voice warnings maybe?
I would post a pic, but they are ugly and not worth it

[acoustics101]

Why does everyone refer to ATI sirens as junk? It's all in their frequency range. It's amazing that so much emphasis is placed on dB ratings of warning devices but not on their frequency.

ATI sirens present the perfect example of while meeting their specified dB output at 100 feet, they rank low as an effective warning device due to their high frequency. An effective warning device needs to provide a significant amount of fundamental tone below 500 Hz. Having high output only at high frequencies makes them little more than noisy toys, as the sound can be unbearable at close range, while being inaudible at less than a mile away inside your home or car. Lower frequencies are not only easier on nearby ears but propagate farther and penetrate structures better.

[jkvernon]

The other reason that there's so much disdain towards ATI is the lack of integrity they have. There have been a number of lawsuits against ATI because they either didn't follow through with what they were told, or they experienced massive equipment failures. Indian Point Nuclear, Lemerick Nuclear, and the city of San Francisco are all great examples of this. In all of those cases, ATI pointed the finger back at the customer rather than taking fault.

[acoustics101]

Hmmm. An inferior product coupled with a "the customer is always at fault" philosophy. I thought that "the customer is always right" is the philosophy of most successful companies. It makes one wonder how they manage to stay in business at all. As Lincoln once said, "You can fool all of the people some of the time and some of the people all of the time, but you can never fool all of the people all of the time". I'd say time is running out for ATI unless they change their ways.

The other reason that there's so much disdain towards ATI is the lack of integrity they have. There have been a number of lawsuits against ATI because they either didn't follow through with what they were told, or they experienced massive equipment failures. Indian Point Nuclear, Lemerick Nuclear, and the city of San Francisco are all great examples of this. In all of those cases, ATI pointed the finger back at the customer rather than taking fault.

[SirenMadness]

I think the reason they use high frequencies in their amps is because of the quality of the drivers; they probably can't take low frequencies too well. Oh well... with all the other stuff the company produces, I seriously think that retiring from the siren business wouldn't be a bad idea for them.

[acoustics101]

I believe it. They are trying to keep the system compact by the size of their horns. What they are really doing is limiting the cutoff frequency to a point higher than optimal for good propagation and penetration. It also limits the low frequency power handing of the drivers.

I think the reason they use high frequencies in their amps is because of the quality of the drivers; they probably can't take low frequencies too well. Oh well... with all the other stuff the company produces, I seriously think that retiring from the siren business wouldn't be a bad idea for them.

[ginbot86]

Well, perhaps the horns' resonant frequency is 1 kHz, and ATI runs it at a resonant frequency. Would that boost the dB rating?

[acoustics101]

In an exponential horn with a high rate of flare, as used on most sirens (and loudspeakers), you will not find any significant peak in output at resonance, as resonances are minimized in horns of this design. Such a horn has a wideband output above its -3 dB cutoff frequency. The best bet would be to use a larger horn with a lower cutoff frequency. This would also increase the power handling of the drivers at lower frequencies.

Well, perhaps the horns' resonant frequency is 1 kHz, and ATI runs it at a resonant frequency. Would that boost the dB rating?