Multiple Sirens?

S

SFR1986

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I don't mean to sound stupid here BUT, what is the meaning of have 2, 3 or even 4 different sirens in an emergency vehicle? I guess I am just not familiar with it. We had 2 when I was back home on the Vol DEPT. I just never saw the need. Unless you have a electronic siren with a REAL Q..none of that electronic crap. Could someone explain this?
 
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Funny you should bring this up... LoL


triton911bj and I are going to be putting a second siren on our ambulance company's big rescue. There have been a lot of complaints and concerns about the currnt on it has in it... It's a C3 200 watt system, but the speakers are mounted on the angles spots on the outer parts of the bumper. People have stated that you dont get enough siren projection to the front. So we are installing a speaker facing directly forward with a whelen siren amp... I'm not sure how some of the guys in the department are going to operate it though... Should prove interesting...


I just wish they would have put a Q on it from the factory... lol
 
I don't know if there is a real "need" for more than one siren. You could extend that to the dual-tone sirens, too. I guess the thinking is that you can get more attention because people will be looking for two vehicles and be more cautious (yeah, right... we're lucky if they even hear either siren over their radios cranked up to 11 or see that big honkin' truck that's in all 3 of their mirrors).


Most of our fire trucks have the Powercall blasting once we leave the station and the Q and air horns thrown in when we get into heavier traffic. I guess there is a benefit of having noises on different tone frequencies at the same time? But 4 sirens? Unless you've got 4 speakers, there isn't much point and even if you do... that's gotta sound horrible.
 
One benefit is that if you have someone who is heavy-handed on the airhorn button, you still have a siren tone active to comply with laws that require you to have your siren and lights on at the same time.


If you are approaching an intersection with your lights and siren going and you only have one electronic siren, the instant you press the airhorn button, you no longer have a valid siren tone until you release the airhorn button.
 
I run 2 different Whelen amps & 3 speakers in my Impala. The one left front gill mounted speaker my employer provided just wasn't enough noise. I like the contrast of off sync wails, and no one expects the moo-tone from a leo vehicle.
 
I run duals with dual speakers. I leave my Code3 3050 remote siren in WAIL, and use my Code3 Mastercom to change tones. It is a true 200watt dual siren set-up, and I have had SEVERAL people ask me how to do it, and tell me how much LOUDER it is with 2 different sirens going at one time!
 
I saw a YouTube video of a very large rescue unit equipped with an electronic siren, a mechanical Federal Q siren, 'stutter tone' air horns, and a three chime horn off a diesel locomotive (yes, a train horn). I don't remember what department it was, but I'm sure it was a small town or county FD somewhere in the US.


After seeing that I thought, what next? I'd love to see a brand new pumper truck with a Federal SD-10 dual tone mechanical air raid siren on it. It'd scare the hell out of everyone.
 
Wailer said:
After seeing that I thought, what next? I'd love to see a brand new pumper truck with a Federal SD-10 dual tone mechanical air raid siren on it. It'd scare the hell out of everyone.
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Lol.
 
Wailer said:
After seeing that I thought, what next? I'd love to see a brand new pumper truck with a Federal SD-10 dual tone mechanical air raid siren on it. It'd scare the hell out of everyone.
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There's a video on Youtube with a Model 2 on top of a ladder truck sounding. They mounted it up there for a washdown ceremony for a neighboring dept.
 
Fdtruckie said:
I have been waiting for a Vision lightbar to show up any day now.
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There are multiple appropriate channels on this site to go through to bring a deal to an acceptable close. Posting this kind of thing as a reply to the person's otherwise unrelated post is not one of them.
 
I've heard two sirens, producing 2 different tones, and I understand the reason for that (Santa Monica PD), but more than 2 IMO just confuses people, and possibly would cause rather than solve a problem. Multiple sirens are not necessarily louder, they just make more noise. I think that the sound pressure emitted from the combined devices will only be as loud as the loudest device, but a second tone, like wail+yelp or hi-lo, while approaching an intersection or congested traffic might help, and that's why true air horns are so useful. Am I correct on this, or am I way off? The often reported problem with all electronics vs a true mechanical is drivers can't readily tell direction of the EV approach. Multiple electronics won't help. This is why a mechanical tone siren, while it may sound better to many of us, probably cannot be heard any better than its effeminate , high pitched sister.
 
I dont know of many emergency vehicles that will use more than two sirens at most.


Here are the following reasons why multiple sirens are useful on emergency vehicles....


1) If one siren fails, you have a backup. The last thing you want is to respond code 3 with no siren.


2) Different siren tones can help drivers move out of the way and or tell them where the emergency vehicle is. I.E. if a vehicle is using the yelp/airhorn simultaneously, you know hes close and wants you to move over. Wail and piercer warn drivers far and near at the same time.


3) Some siren tones catch people's attention more, and multiple siren tones simultaneously REALLY get peoples attention.


4) Having more than one siren on your vehicle makes it louder, which we all know is very helpful when responding.
 
i have 2 sirens running in my truck, i will use the Whelen will 2 speakers most of the time, If im in a congested area i will add in second siren which has a 100 watt speaker hooked up, i will say that people DO move much sooner with both on. but it also annoys me so i dnt do it unless i need too....
 
I am the D/Chief of a very large agency. I had these put on, using the Carson 441 format, and have used them for over 10 years now. I have over 50 units with these sirens. They increase resposne to other drivers by utilizing both wail and yelp, throwing the sound further down the road as well as the bounce affect coming into intrsections. I am convinced they are safer and draw more atrtention to the responding unit. I have now added them to all of my staff vehicles for the same reason.
 
I myself run duel siren. Federal Signal Smart Siren and a Carson Volunteer series siren. I have noticed myself that people also get out of the way quicker when I run duals. I have two different sounding wails and it does get attention of drivers on down the road. Also as said in earlier posts. Running the wail/yelp or wail/pri. does have both and near distances covered. I do believe running duel sirens are much safer and I will not be running just one tone anymore. Now on the part that people has 3 or 4 sirens. That is overkill. I've only seen two trucks that run more than two. One is local that has 2 electric and 1 mechanical. Now most of the time they only run 2 but I have seen them run all three. To me it causes people to panic more when there is nothing but scrambled noise behind them.
 
Before I retired as Chief...I ran dual 100W sirens also. Set the Carson to wail, and had a Powercall X71 with the traditional "Powercall" sound on the other. It worked out great for me...Even using the "air horn" function on the Carson, I still had uninterrupted siren sound from the Powercall... Anything more than 2 separate tones creates gabled noise in my opinion...
 
I run dual sirens, and ive noticed a difference from 1 to 2 sirens. The first siren i use is a carson sc-1022 on mechanical, hooked up to a foot switch, second is a whelen box, on wail and yelp. keeps me legal for less (ha ha ha). Makes no sense to have more than 2 sirens on a vehicle. you got a primary and secondary siren.
 
Dr. Dennis Stouffer said:
The often reported problem with all electronics vs a true mechanical is drivers can't readily tell direction of the EV approach. Multiple electronics won't help. This is why a mechanical tone siren, while it may sound better to many of us, probably cannot be heard any better than its effeminate , high pitched sister.
Click to expand...


I respectfully disagree with the last point. :nono: Mechanical sirens CAN be heard better than electronic sirens. The reason:


Why the controversy between mechanical and electronic sirens?


Is it just the modern vs. the old fashioned diehard? Well, it is true electronic sirens made their entrance to the emergency warning business in the 1960’s coinciding with the industry wide increase in electrical demand brought on by more lights, radios, computers, and new EMS equipment. Typical mechanical sirens of the era drew 200 to 300 amps compared to only 12 to 17 amps for the new electronic style. Switching sirens was an easy trade off, many cars were not air conditioned and sound insulation was only minimal. Electronic tones from alarms, buzzers, games, and computers were not common. Thus the new sirens enjoyed an acceptance for a season. However, today it’s a different story.


[Broken External Image]:http://www.timberwolfsirens.com/Assets/Images/mechanicalSirensSm.gif


A mechanical siren produces a spiraling square wave, thus offering a very strong and focused pattern.


[Broken External Image]:http://www.timberwolfsirens.com/Assets/Images/electronicSirensSm.gif


Electronic sirens are notorious for having dead spots and creating noise pollution without direct sound penetration making them less effective.


[Broken External Image]:[URL]http://www.timberwolfsirens.com/Assets/Images/upArrow.gif[/URL]


Why is it said that mechanical sirens are more effective?


One must look at the physics of the air movement! Electronic Sirens translate a transistor generated signal to an electro magnetic driver which pulses a 3/4 inch diameter diaphragm back and forth rigorously 1/32 inch to move the air in a sine wave form, creating the familiar Whoo Whoo sound projected from the speaker horn. The electronic siren works like an ice cream truck speaker, creating sine waves like ripples on the lake which go and go and go in all directions. Mechanical Sirens pump air, compressing and accelerating it to more than 130,000 inches per minute (or 124 miles per hour) where a rotor pulses it, off on, off on in a square wave form which spirals at 9,000 revolutions per minute as it expands from the 2 3/4 inch diameter guiding throat. The Mechanical Siren’s spiraling wave is like an ocean’s wave curl projected from a short guiding throat, on off on off, making the Whoo sound. The operator controls the volume and the pattern with the foot switch.


and also...


How does speed affect a siren?


Vehicles with electronic sirens tend to out run their sound waves at approximately 55 mph. This phenomena is so common in the industry, they call it sirencide. Vehicles equipped with mechanical sirens do not outrun their sound waves. The air or shock wave is accelerated to more than 120 mph allowing the vehicle’s speed to never be a concern.


These exerpts were copied from Mechanical Sirens Frequently Asked Questions


if yous guys want more info, also check out


The Sounds of Sirens - Don't be alarmed ... be informed - LA Fire Depatement ... LA Community Policing


:thumbsup:
 
How does speed affect a siren?


Vehicles with electronic sirens tend to out run their sound waves at approximately 55 mph. This phenomena is so common in the industry, they call it sirencide. Vehicles equipped with mechanical sirens do not outrun their sound waves. The air or shock wave is accelerated to more than 120 mph allowing the vehicle’s speed to never be a concern.


i will totally have to agree with the sirencide with speed. that said i run with a whelen hhs 2100 with 100w siren speaker and i will get up behind someone for a good stretch and it is like the never heard me. prime example and jeep wrangler with the doors and everything off, it was like the driver was deaf or didnt care. i would have to agree with having a siren the either gives off multi tones or 2 separate sirens no more. and the q siren is also a big help
 
WhiteLite03 said:
Mechanical sirens CAN be heard better than electronic sirens.
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But nowadays most people think a mechanical siren is a fire engine siren. A fire engine doesn't 'need' a mechanical siren any more than other types of emergency vehicles. If mechanical sirens are so great, then they should be used on all types of emergency vehicles, not just fire engines.
 
Wailer said:
But nowadays most people think a mechanical siren is a fire engine siren. A fire engine doesn't 'need' a mechanical siren any more than other types of emergency vehicles. If mechanical sirens are so great, then they should be used on all types of emergency vehicles, not just fire engines.
Click to expand...


I don't have a problem with that line of thought. I would assume the reason they are no longer used on anything other than Fire/EMS apparatus is due to the size and amp draw of the units. Modern police cars and other small response vehicles simply don't have any extra room in them with all of the other equipment that is being installed. But I'm all for putting them in everything, lol.
 
First, let me say clearly mechanical sirens can be heard way better than electronic.


But the reason why every emergency vehicle doesnt have a mechanical siren is because they don't need them. I firetruck is much large than a police car, therefore it needs a louder warning system. Just like an 18 wheeler needs a louder horn because it takes longer to stop. A police car moves extremely quickly, therefore the audible warning doesn't need to be as loud. Also, a mechincal siren only has one tone, where an electric siren has many, so police like it. And there's no PA on a mechanical, so cops can't use it.


But all other emergency vehicles besides cops (ambo's, rescue units) should have a mechanical siren
 
Wailer said:
I saw a YouTube video of a very large rescue unit equipped with an electronic siren, a mechanical Federal Q siren, 'stutter tone' air horns, and a three chime horn off a diesel locomotive (yes, a train horn). I don't remember what department it was, but I'm sure it was a small town or county FD somewhere in the US.
.
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You are thinking of Walkersville, MD, Heavy Rescue 24, a 2001 Pierce Quantum that has dual rotorays, electronic siren, Q2, airhorns, and train horns mounted in front.
 
gman021 said:
A firetruck is much large than a police car, therefore it needs a louder warning system. Just like an 18 wheeler needs a louder horn because it takes longer to stop.
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But what about large specialty emergency vehicles, some of which are bigger than fire engines (e.g. mobile command posts, police emergency response units, and ambulance buses)? They use electronic sirens.


I still don't buy the argument that a fire engine 'needs' a mechanical siren more than any other type of emergency vehicle.
 
gman021 said:
First, let me say clearly mechanical sirens can be heard way better than electronic.

But the reason why every emergency vehicle doesnt have a mechanical siren is because they don't need them. I firetruck is much large than a police car, therefore it needs a louder warning system. Just like an 18 wheeler needs a louder horn because it takes longer to stop. A police car moves extremely quickly, therefore the audible warning doesn't need to be as loud. Also, a mechincal siren only has one tone, where an electric siren has many, so police like it. And there's no PA on a mechanical, so cops can't use it.


But all other emergency vehicles besides cops (ambo's, rescue units) should have a mechanical siren
Click to expand...

If your argument is that because police cars are faster, therefore they don't need a mechanical siren, it seems it would be a flawed one, seeing as how electronic sirens are useless above 55 or 60 mph for clearing traffic.


Either way, it doesn't matter, they're not going to start putting mechanicals on police cars anytime soon; It's just a fun topic of conversation.
 
WhiteLite03 said:
If your argument is that because police cars are faster, therefore they don't need a mechanical siren, it seems it would be a flawed one, seeing as how electronic sirens are useless above 55 or 60 mph for clearing traffic.

Either way, it doesn't matter, they're not going to start putting mechanicals on police cars anytime soon; It's just a fun topic of conversation.
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It's my understanding not much will clear traffic if your going 60 mph, and you probably won't be going that fast if there is traffic ahead or in your way


But technically, the siren should travel faster because the speed of sound is far greater than 60 mph
 
On several occasions I have not heard electronic sirens until they were almost next to me. About two times, amb. were approaching blind at intersections, and I didn't hear anything. This is partly why LAFD and LACo started using Hi-Lo air horns almost 40 years ago. It is also why both dept's. have gone back to mechanicals on larger apparatus, though squads and ambulances still use electronics for all the usual reasons. The Co. is using eQ2's and the guys like them even if the yelp sounds terrible.
 
gman021 said:
But technically, the siren should travel faster because the speed of sound is far greater than 60 mph
Click to expand...

I was thinking just that.
 
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