Thread: Dual Sirens

Looking at buying a new truck, I have always wanted to run dual sirens. I have a Carson SC-1022, and I always run the Mechanical tone, however I want to make a little more noise. I have an extra brand new speaker here and was thinking about adding a Able 2 (Sho-Me) 30.2504 Undercover Siren when I install everything in my new vehicle. Anyone have any thoughts on this? Or may know of another good reliable but somewhat in expensive siren. I want a Wail, Yelp, Phaser (if possible), and Air Horn.

Whelen makes a nice dual siren thats a remote flush mount that you can program to run a numerous different tones with the mechanical tone. i dont know the model number but i had one for a little while really liked it...and our ambulance's had a couple of them.

Our local Battalion chiefs trucks have a Whelen siren that plays dual sounds. It sounds like several vehicles coming down the road.

i run a 2nd siren through my smart siren keypad, which is an Omega 90, i hit up the 2nd siren when going through an intersection, def gets the job done and worth it. i only run 1 sound from the 2nd siren, i dont think you need to start scrolling through different sounds on your backup siren, so the sho me siren would be perfect for your idea and save you $$. you can get pa300's or the sho me undercover sirens for like $30-40 on the site, just remote it and there ya go

Hey guys, I like the idea with the Whelen siren, but have a brand new Carson that I love. I will very likely stick with the idea of the sho-me siren and use the single tone. Thanks for everyone's help!!

Originally Posted by twodogs603

It sounds like several vehicles coming down the road.

...and the jury is still out as to whether that's a good thing or not. We had some departments try dual tones up here and had so many complaints from the public that they took them out. It's confusing at an intersection when you're looking for 2 vehicles and only see one. I'm very used to Emergency Vehicle operations and sirens, and it confuses me when I hear a dualtone vehicle.

Using two speakers and a 200 watt capable amp is a much better way to go. More volume, less cancellation, more recognizeable.

Originally Posted by leftcoastmark

...and the jury is still out as to whether that's a good thing or not. We had some departments try dual tones up here and had so many complaints from the public that they took them out. It's confusing at an intersection when you're looking for 2 vehicles and only see one. I'm very used to Emergency Vehicle operations and sirens, and it confuses me when I hear a dualtone vehicle.

Using two speakers and a 200 watt capable amp is a much better way to go. More volume, less cancellation, more recognizeable.

Cancellation???

Just get a code 3 Von, they are all 200 watts, and only run 1 siren tone!

Originally Posted by leftcoastmark

...and the jury is still out as to whether that's a good thing or not. We had some departments try dual tones up here and had so many complaints from the public that they took them out. It's confusing at an intersection when you're looking for 2 vehicles and only see one. I'm very used to Emergency Vehicle operations and sirens, and it confuses me when I hear a dualtone vehicle.

Using two speakers and a 200 watt capable amp is a much better way to go. More volume, less cancellation, more recognizeable.

Really? In SoCal, it seems to improve the public's attention! If they are looking for a second vehicle, I'd imagine that's a plus don't you think? Perhaps it's just the drivers down there, they can't even drive in 1/10th inch rain.

Originally Posted by Jared @ 911Lights

Cancellation???

The two speaker's sound waves interfere with one another, causing cancellation (reduction in SPL) at random points in the tones. You don't typically get that in single-tone systems with 2 speakers because the tones coming out of the speakers are synchronized.

Originally Posted by EVModules

Really? In SoCal, it seems to improve the public's attention! If they are looking for a second vehicle, I'd imagine that's a plus don't you think? Perhaps it's just the drivers down there, they can't even drive in 1/10th inch rain.

Just saying what we've seen up here. Two tones seem to confuse drivers as they're waiting for a second vehicle to come by. My fear is if they get used to one vehicle with 2 tones, then when 2 vehicles (each running 1 tone) come into an intersection, the drivers won't know to look for the 2nd emergency vehicle.

Maybe I'm old school, but we were always taught that if you have multiple vehicles responding, the first should run an active tone and the 2nd should run a less active tone - but whatever the tones, make them *different* so people know that 2 vehicles are coming. The dual-tones kind of defeats that.

That requires perfectly asynchronous tones, perfect speaker alignment, perfect observer positioning. At best it's hard to produce in laboratory setting, it is completely irrelevant to emergency warning systems.

-Jared

Originally Posted by leftcoastmark

The two speaker's sound waves interfere with one another, causing cancellation (reduction in SPL) at random points in the tones. You don't typically get that in single-tone systems with 2 speakers because the tones coming out of the speakers are synchronized.

Not bashing anyone out there.


There are many pros and cons to the dual siren, I like it 1) because all of the real fire apparatus in my area runs a regular electric siren with their Q, and running with a Q and a basic electronic siren usually will intimidate people. If your coming up to the scene of a fight. I installed dual sirens in a vehicle exactly like my current SUV for a guy who is a Firefighter/Paramedic/LEO and his dual sirens helped him tons a few times. Him running his Wail and the other siren in Yelp to a scene managed to disperse the crowd before his arrival. I know this is only one pro but seems pretty life helping to me.

I run a dual-mode Unitrol Omega 90 in my primary response vehicle and it definitely improved clearing traffic and intersections when responding to emergencies over using a single mode sirens. Also, most FD apparatus run a mechanical siren inconjunction with a single mode electronic siren here on Long Island plus using very loud Grover Stuttertone airhorns. You can't beat that combination!

Go with a Power Call Siren since you are already running a "mechanical"

www.powercallsirens.com

Originally Posted by ark_firefighter

Go with a Power Call Siren since you are already running a "mechanical"

www.powercallsirens.com

Those things are junk, they have the worst tones I've ever heard...

There are tons of other sirens out there that have the "Powercall" tones that also have much better sounding regular tones...

you need an hhs2200 to go with your carson. I run the powercall on it and i want you siren, the carson, so i can run a q with the powercall. best sound ever. would you be willing to sell your carson? i could trade you another siren/light controller nib possibl?

No, sorry I actually just put my Carson in because I got it new. If your looking for a Carson, PM me and I'll see what I can do.

Originally Posted by jun112ior

you need an hhs2200 to go with your carson. I run the powercall on it and i want you siren, the carson, so i can run a q with the powercall. best sound ever. would you be willing to sell your carson? i could trade you another siren/light controller nib possibl?

Definitely like the idea of running a siren that sounds like a powercall with the Mechanical siren! Most likely I will do that.

Originally Posted by Jared @ 911Lights

That requires perfectly asynchronous tones, perfect speaker alignment, perfect observer positioning. At best it's hard to produce in laboratory setting, it is completely irrelevant to emergency warning systems.

-Jared

30 years in commercial sound reinforcement and 13 years in full time emergency warning sales (this isn't a part time hobby for me), including dozens of courses I've instructed on emergency warning setups, I have a good understanding of how sound projection works. I'm not saying that with 2 speakers running off 1 amp you won't get ANY cancellation. I'm saying that it's faaaaar less than with dual amps (dual tones), and the cancellation is predictable. The "perfectly asynchronous tones" (I think you really meant "synchonous" tones) is simple to do since you're running 1 amp. The speaker cones move in phase with one another. You're still going to get SOME cancellation between the speakers, where the waves meet each other, but if you mount them like you're supposed to (30" apart, minimum), it'll be minimal, and can even be used to your advantage.

The tests we've done, both at customer sites and in anechoic chambers, show a 3-4 dB gain at the 45degree axis and straight ahead (H-V). If you put the speakers side by side, (no space between the two speakers) you get a 5-6dB gain straight ahead, but lose 2-3 dB at 45 degrees (vs. 1 speaker) - see polar plot image, below. This is a perfect example how the speakers can actually help each other (the straight-on number) and also cancel each other (the 45 degree numbers). However, we've done this side-by-side setup for hwy patrol cars and it works fantastic. WAY louder out front where they want it on the hwy, and they don't care about the loss of 45 degree volume (which is only 2-3dB anyway - barely noticable) because they rarely, if ever, go code3 through intersections.

However, my point is that with 2 speakers running 1 tone (1 x 200watt amp), is that the performance is predictable, so if you know what you're doing, you can tune the performance of the audible warning. With dual amps/dual tones, you have sounds going all over the place and it's not predictable so you don't know where your cancellation is, and where it isn't. It goes to your "perfectly asychronous tones" you mention - which is exactly my point. This (cancellation, standing waves, etc.) is a basic concept in home theatre setup and commercial sound reinforcement setups, and it's no different in emergency warning.

Cheers
Mark
1 vs 2 speakers.jpg

Originally Posted by leftcoastmark

30 years in commercial sound reinforcement and 13 years in full time emergency warning sales (this isn't a part time hobby for me), including dozens of courses I've instructed on emergency warning setups, I have a good understanding of how sound projection works. I'm not saying that with 2 speakers running off 1 amp you won't get ANY cancellation. I'm saying that it's faaaaar less than with dual amps (dual tones), and the cancellation is predictable. The "perfectly asynchronous tones" (I think you really meant "synchonous" tones) is simple to do since you're running 1 amp. The speaker cones move in phase with one another. You're still going to get SOME cancellation between the speakers, where the waves meet each other, but if you mount them like you're supposed to (30" apart, minimum), it'll be minimal, and can even be used to your advantage.

The tests we've done, both at customer sites and in anechoic chambers, show a 3-4 dB gain at the 45degree axis and straight ahead (H-V). If you put the speakers side by side, (no space between the two speakers) you get a 5-6dB gain straight ahead, but lose 2-3 dB at 45 degrees (vs. 1 speaker) - see polar plot image, below. This is a perfect example how the speakers can actually help each other (the straight-on number) and also cancel each other (the 45 degree numbers). However, we've done this side-by-side setup for hwy patrol cars and it works fantastic. WAY louder out front where they want it on the hwy, and they don't care about the loss of 45 degree volume (which is only 2-3dB anyway - barely noticable) because they rarely, if ever, go code3 through intersections.

However, my point is that with 2 speakers running 1 tone (1 x 200watt amp), is that the performance is predictable, so if you know what you're doing, you can tune the performance of the audible warning. With dual amps/dual tones, you have sounds going all over the place and it's not predictable so you don't know where your cancellation is, and where it isn't. It goes to your "perfectly asychronous tones" you mention - which is exactly my point. This (cancellation, standing waves, etc.) is a basic concept in home theatre setup and commercial sound reinforcement setups, and it's no different in emergency warning.

Cheers
Mark
1 vs 2 speakers.jpg

But it sounds cool, and that's all that matters.

...right?

Originally Posted by leftcoastmark

30 years in commercial sound reinforcement and 13 years in full time emergency warning sales (this isn't a part time hobby for me), including dozens of courses I've instructed on emergency warning setups, I have a good understanding of how sound projection works. I'm not saying that with 2 speakers running off 1 amp you won't get ANY cancellation. I'm saying that it's faaaaar less than with dual amps (dual tones), and the cancellation is predictable. The "perfectly asynchronous tones" (I think you really meant "synchonous" tones) is simple to do since you're running 1 amp. The speaker cones move in phase with one another. You're still going to get SOME cancellation between the speakers, where the waves meet each other, but if you mount them like you're supposed to (30" apart, minimum), it'll be minimal, and can even be used to your advantage.

The tests we've done, both at customer sites and in anechoic chambers, show a 3-4 dB gain at the 45degree axis and straight ahead (H-V). If you put the speakers side by side, (no space between the two speakers) you get a 5-6dB gain straight ahead, but lose 2-3 dB at 45 degrees (vs. 1 speaker) - see polar plot image, below. This is a perfect example how the speakers can actually help each other (the straight-on number) and also cancel each other (the 45 degree numbers). However, we've done this side-by-side setup for hwy patrol cars and it works fantastic. WAY louder out front where they want it on the hwy, and they don't care about the loss of 45 degree volume (which is only 2-3dB anyway - barely noticable) because they rarely, if ever, go code3 through intersections.

However, my point is that with 2 speakers running 1 tone (1 x 200watt amp), is that the performance is predictable, so if you know what you're doing, you can tune the performance of the audible warning. With dual amps/dual tones, you have sounds going all over the place and it's not predictable so you don't know where your cancellation is, and where it isn't. It goes to your "perfectly asychronous tones" you mention - which is exactly my point. This (cancellation, standing waves, etc.) is a basic concept in home theatre setup and commercial sound reinforcement setups, and it's no different in emergency warning.

Cheers
Mark
1 vs 2 speakers.jpg

is there a "best" position to place the speakers ? i have a roof rack (basket) and i was wondering if it's better to put them high or the classic placement below the front bumper ? i don't want to put them im my grill since that will reduce the amount of airflow to my engine .
thks

Anyplace in front of the radiator, preferably with no obstructions in front of the speaker. Which pretty much makes push bumper mounting the best option. Years ago, sirens on roofs was common but noise & OSHA did away with it for good reason.

Mark,

Your chart, well actually Federal Signals chart, does not indicate the effects of different tones, it shows one speaker compared to two while using the exact same tone. In that circumstance, the best scenario is 200 watts coming from a single speaker.

Been running 2 amps and 3 drivers for years. One of the few instances where more is better.

I run dual amps, both hooked into the horn function with resisters. Works flawlessly!

Problem solved! My dual siren... SVP SS741MG

SS741MG_small.jpg

If anyone is looking to run dual tone I would go with the Sound-Off 380 Seres remote siren, it sounds absolutely awesome and to my it seems way louder then any other siren. Plus it has a 3 pos slide switch and aux buttons with slide switch mapping. Awesome siren I must say!

That was pretty much replaced by the LCS850MG which now has computer programability:

Originally Posted by jluisi86

Problem solved! My dual siren... SVP SS741MG

SS741MG_small.jpg

Originally Posted by Jared @ 911Lights

That was pretty much replaced by the LCS850MG which now has computer programability:

I always get good feedback from it