"Outdoor Sirens"

[Jim_Ferer]

r4tbolts wisely said, "Years ago before pagers fire sirens wailed in the middle of the night to summon the Volunteers. This thing now about sirens are for you sitting on the porch, sipping tea on the deck or at the park is a poor excuse for poor siren coverage, crappy sirens (2001's) or sloppy care of the sirens in any given community. "

It's called "managing expectations." Teach the public to expect less.

[MattDean1003]

I highly disagree with all of the "cheap sirens, cheaply made" comments. It's not a "you get what you pay for" kind of deal. These aren't cheap knockoff electronics, these are high powered outdoor warning devices. These are 10 and 20 thousand dollar sirens. We have to remember that. We also have to remember that the siren reps READ these boards. Comments such as "Crappy sirens (2001's)" really have no reason to even be typed on here. I don't honestly believe that any siren made today is "crappy". Build quality is build quality. They're built to last. I've been keeping up with the posts pertaining to "crappy sirens" and you want to know something that I fail to see in nearly ANY of them?

Maintenance.

Drive your car a year without changing the oil or lubricating something and let's see if it lasts. A little work goes a long way. I don't want to see or hear anything about "maintenance free". Think that's maybe why these "crappy" sirens are failing?


Just because you don't like the way one sounds doesn't mean it's a bad siren. People cut the Whelen Vortex down on here for years. When I lived in Nicholson, the Vortex near my house was a little under a mile away, and it brought me out of the house with our dishwasher and washing machine BOTH going. To this day, none of Jackson County's sirens have failed a test.

Yes there are sirens that I have been impressed with, and there are sirens that I haven't been impressed with. The fact of the matter is that they were still heard. The Eclipse 8 in Winder wasn't that loud, but I was also a quarter mile away from it and it was being blocked by numerous buildings. Hell maybe even a half a mile away.

The Messner Bro's Machine Shop siren is just as high pitced as a 2001 but nobody on here has ever complained about it.

To add to the Outdoor Warning Sirens thing, what do you think would happen if a siren company stated that the sirens can be heard indoors AND outdoors? One person would sue them for every penny they had. Come to think of it, out of ALL the siren ads I've seen posted over the years, NOT ONE OF THEM states that they're audible indoors. Insulation is much better nowadays than it was back when those siren were king, too. More noise blockage.

Guys, I'm not taking sides here. However, I AM defending the companies against producing "crappy" products.

To add one thing, one poster said he was pumping gas and heard the sirens but his radio was at home on his dresser. That just proves the OUTDOOR siren part even more. He was outdoors and heard them.

Jason, be ready to moderate this. I'm sure I just swatted at a hornet nest with a stick. I'm sorry if I offended anyone.

[500 AT fan]

I find it funny how lots of people keep bashing high pitched/single tone sirens, while plenty of high pitched single tone sirens do a fine job at warning the public.

[CJ]

MattDean you make a very good point. The only problem with Federal is their activation systems and the added cost for the cities needing more sirens to get the same coverage.

2001s aren't cheap and the sirens themselves seem to be pretty reliable. Software seems to be the issue and unfortunately the nature of programming means that this isn't particularly hard to come across.

As for the Eclipse 8, it isn't exactly the biggest or highest-rated siren around. It takes a lot more power to get an omni to give the same directional sound output as a rotating siren as the omni has it's airflow spread around, rather than beamed in one direction.

I heard my first siren ever on saturday when I was working on my kart at the track - now it wasn't particularly loud, from a mile away at most. It was still audible although I missed the windup as someone had a generator going. And that siren is next to the river Mersey and the small Carters type sirens are only what, 3hp odd for an omni? I was impressed with the range. It is said to be audible about 3 and a half miles away, over the other side of the river in Garston. Though, there was an oil refinery blocking the sound out.

To be honest, as long as a siren is audible and the people around know what they sound like, it's all good. Pitch doesn't matter unless you're after coverage... and even then conditions affect ANY siren, of any pitch and power.
And I don't think that you were swatting at a hornet nest.

[dilloncarpenter]

Matt, you pretty much hit it dead on IMHO. If anyone, you would have me to back you up on that.

My judgment on newer sirens depends. So far I am not impressed with the T128's and 2001, but before I make a final decision I would prefer hearing them in person or up close first.

In my bedroom, since I am the weather geek of the family, I have a Midland NOAA Weather Radio. While it does not give the same type of warning as sirens, it comes straight from the NWS in Norman so that's a pretty damn good source, if you ask me. I'm not saying the NWS is always right, but it is sure worth the $30 to protect your family.

[weasel2htm]

All households should have a weather radio, with houses being built tighter, it is harder for even the vintage sirens to penetrate though the house. As for older homes, well I'm sitting here at my computer with my poor little windows A/C working overtime, why do I bring this up? Well many years ago, my parents were in bed asleep, my mom hears the sirens (SD-10 6.4 blocks away as the crow flies) she wakes my dad up who tells her it is just the window A/C making a funny noise, she makes him turn of the A/C just to be sure, and dad was wrong, the sirens were actually blowing. Now my parents have long since gotten central air (and recently a weather radio) I have no idea if the 2001 siren that replaced the SD-10 would be heard or not in that bedroom, even with the A/C gone.

[Daniel]

One of the topics that rarely arises concerning siren efficiency is rotating versus omnidirectional. Many cities have opted for rotating sirens so that they can save money by using fewer and more powerful sirens. While proponents of rotating sirens (mechanical or electronic) say that sound aimed at a specific location is louder, they forget that apart from that brief, regular interval, the siren is pointing away and is significantly quieter than an omnidirectional unit. It is also difficult to differentiate alert and attack signals with rotating sirens. A recent video of a 40V2T at a distance of one mile illustrates the difference from the many videos of 2001's in neighborhoods where distant sirens are barely audible except for those two seconds where it is pointing toward the camera.

[System 7000]

I agree with MattDean. All modern sirens serve their purpose. The FS 2001 is not as bad as people make out. It is very efficient, and it does do a good job of warning people. I think that the main reason that the 2001 meets with such a hostile reception from many on this board is that it replaced the Thunderbolt in FS's line-up. To an enthusiast, almost nothing could have matched the Thunderbolt. But remember that to non-enthusiast siren operators, the Thunderbolt was not particularly efficient, offered no battery back-up, and required a large amount of time-consuming maintenance.

Even the ATI SoundBlaster range serves its purpose. It is not a good siren, but it does do its job as an outdoor warning device. Let's not forget that the ATI does do very clear voice announcements. If you stop thinking of it as a siren, and think of it as a warning system, then it becomes much less of a 'hate target'. I personally like to think of ATIs as P.A. systems that also beep.

I also agree with Daniel about the benefits of omni-directional sirens over directional sirens. I am aware that it has been posted before, but this link has a very good coverage graphic at the end of the page that illustrates a rotating siren's sound coverage. I know that it will be unpopular for me to say this, but in terms of efficiency, sound penetration and coverage characteristics and maintenance requirements, a Whelen 2900 is one of the best sirens available today...

Finally, as Jeb mentioned a while back, remember that the general public doesn't care about siren tones - to most people, all sirens are an unpleasent racket.

Regards,
Jerry.

[acoustics101]

The real issue here isn't that the newer sirens are necessarily cheaply made. The manufacturers are doing their best to provide the maximum dB rating at 100 feet using the least HP or kW. It is much easier to accomplish this at higher frequencies. By using higher frequencies you don't need as large of horns with low cutoff frequencies and generally the power requirements can also be lower, as greater directivity indices can be achieved in a smaller space. This is particularly the case with the 360 degree radial horn arrays seen on some electronic units, as they are already of immense size.

The problem is that achieving an x number of dB at 100 feet really tells you very little of how well the unit will perform in real world conditions at a distance, involving frequency dependent losses related to atmospheric absorption and penetration of common construction materials. We already know that some manufacturers only test their units in anechoic chambers and interpolate how they might perform from a distance.

Even when you reach the usable outdoor 70 dB radius, you still have to contend with additional losses of up to 55 dB or more due to trying to penetrate masonry walls of buildings. Due to this, a 70 dB outdoor radius is no longer effective for indoor penetration. To rate all units on an equal basis, we might consider a distance, such as 1 mile, in which the measured SPL is in excess of 70 dB. It will start becoming apparent at this distance that lower frequencies are in fact more effective. It will become even more apparent from greater distances, such as 2 miles, for any source that can still supply the required output. In all cases the higher frequencies are always the first to go. It is first noticeable in the upper harmonics.

A frequency spectrum that peaks below 500 Hz will lose significantly fewer dB with distance to begin with than a frequency spectum that peaks around 1 kHz, especially when the distance is great. We are not simply talking about the fundamental frequencies here, but the effective frequency due to the spectrum of the tone with all of its harmonics, which effectively increases the fundamental frequency by up to a factor of 1.4.

There is also at least 5 dB less loss for 500 Hz penetrating common construction materials than at 1 kHz. This is the very reason the older sirens can be heard in places the newer ones cannot. It's not a matter of manufacturing quality, but a matter of acoustics and physics.

[System 7000]

In many ways, the Sentry dual-tone models have the best compromise:

The standard 20V2T will provide 460/920 Hz giving the user the perfect balance of penetration power and reflection benefit.

(The 40V2T is 600/800 Hz.)

Regards,
Jerry.