What vehicle sirens are loudest at a distance?

[StonedChipmunk]

Would it be possible to put a volume knob somewhere between the siren and the speaker? I was hoping to get a civilian-legal PA/horn unit which I could tone down the horn if needed so I don't get screwed. But at least the PA is adjustable.

[Robert Gift]

Yes. Simplist would be to install a variable resistor (potentiometer) in series with the output. But it would have to be heavy duty and that would be expensive.
Better would be several fixed resistors which could be added in different combinations to create several output volumes.

Or just block the speaker with sound absorbant material.

[StonedChipmunk]

Ah, the magic of Kleenex and duct tape!
(This is what I did with a small electric siren I found in a bargain bin at a small-time electric store. Ironically, it was named Microsoft! I'm not joking! Anyways, it was a 9-12V that I just hooked up to a small converter that I have hooked up to a timer circuit along with a rotating light that I use as my alarm clock.)

[q2bman]

I too used to think the volume knob was for siren output but no, it's for the preamp PA input to the amplifier. Adjusts the PA output. Oh well.

I'd be a bit carefull with your inline resistance ideas for volume controll. I burned up a PA 300 trying that.

[thunderbeam63]

It always sounds like the rescue trucks are the loudest.

[Undertaker]

Our firetrucks here have both electronic sirens (100 watt Federals) with 2 speakers and a trusty Q2-B on the bumper. Going out and listening as the sound disappears in the distance, the first and last sound heard is that sound coming from the Q. Sorry but a mechanical siren just stirs sound waves better than an electronic.

[Robert Gift]

Are those designed for two speakers?
If 100 watts into two 100-watt speakers, the power divided into each will be insufficient and they will not be as loud as one speaker.

What I like best about speakers is that they can be silenced instantly.
I am frequently pressing the microphone key as soon as we determine siren is no longer needed - like before entering an intersection where everyone has stopped. Also when turning and the speakers are about to aim right at pedestrians or bicyclists. More than once a mother with a child in her stroller was really appreciative!

Also one can use the P.A. to ask people to move. The Q scares some and they freeze.
Silencing a blaring siren and a calm, gentle, "Can you please squeeze right (or whatever)?" has helped a lot.

Also, the speaker aims sound more ahead so less pollution into homes and businesses.
But that is a problem when arriving at intersections.
Not as much sound will be detected by traffic approaching from right and left. For that we have additional LED lights in the front wheel wells facing directly right and left. Not noticed when not on.

[Undertaker]

When we switched from mechanical (28's) to electronic (58 watt Directors) on our ambulances we lost volume and a considerable amount of traffic control and driver respect because the electronic siren did not project the sound as well and as loud as the old mechanical sirens. The upside was like Robert said, we gained a PA which we could and did talk traffic out of our way and our headlights didn't dim when we turned the siren on like the mechanical sirens did. Of course we only had one battery and we would have to change them 2 to 3 times a year. I looked on my funeral coach the other day and there is no place to put a small speaker in front of the radiator and there certainly isn't anything substantual enough to mount a 28 or C4 under the hood let alone finding enough room to do that. I do not miss those days at all.