The Siren Board

soccerdude7330 wrote:For the unmarked cabinet on the right, my guess is that it would be some kind of power inverter specifically made for the demo rig, to keep the batteries charged.

Ditto. I believe it adapts the 12 V from the truck into something else. Its size is most likely from the fact that the Mod's high wattage is near the capacity of the truck itself.

ginbot86 wrote:Ditto. I believe it adapts the 12 V from the truck into something else. Its size is most likely from the fact that the Mod's high wattage is near the capacity of the truck itself.

Modulators don't pull their power from AC, they pull their power from the four 12V batteries in the battery box. Just like Whelen sirens, you must have charged batteries installed in the cabinets for the siren to run.

The only reason you need AC power is for the charger to keep the batteries topped off when it's not in use.

I'd say it's most likely a DC-DC converter to step up the 12v to the 24v or 48v the siren needs.

I just had a crazy thought pop into my head upon seeing that picture, What if there was a way to use the siren in the truck bed as a horn for the truck? I'm not exactly sure how or if this can be done, any ideas?

whydoesthisalwayshappento wrote:...I'm not exactly sure how or if this can be done, any ideas?

It's more likely the power draw would be too high. And it'll deafen everyone in the vicinity.

What's also interesting about this setup is that there is not a dummy cell in the stack. For a Modulator to work right, there needs to be a bottom half and top half facing each other to make the correct 360 exponential horn shape. This unit's bottom cell has the doors, making me think it would have active drivers in there. None of the cells are reversed to face each other, so that bottom cell is either inactive, as it should be (yet is has the driver doors), or it is just inefficiently beaming sound straight down.

None of the cells are reversed to face each other, so that bottom cell is either inactive, as it should be (yet is has the driver doors), or it is just inefficiently beaming sound straight down.

With all due respect, if the bottom on is indeed active & the sound is being shot down like the others, it doesin't really matter its just a demo, besides, what they don't know won't hurt the company

ginbot86 wrote:Ditto. I believe it adapts the 12 V from the truck into something else. Its size is most likely from the fact that the Mod's high wattage is near the capacity of the truck itself.

I think that there is a battery pack powering the siren. Assuming that there's no dummy cell, it's a 4016, so it takes up just a bit over two hp, which isn't that much for a generator, but I don't think that the truck is powering the siren or charging the batteries at all.

Great pics, Eric! What I'd do to drive that...

What I'd do to drive that...

Haha. I'd drive by my worst enemy's house and say into the microphone "F*** YOU ENTER NAME HERE!!!!!!!! lol

I would disagree; It makes sense in manufacturing to have just a stockpile of saucers all made the same way, including the doors, rather than build a 'special' set of saucers without doors for the very bottom, and always have to keep a running inventory of them in addition to ones for the active cells.

Although now that I've written this, and then gone to my PDF's of the Modulator manual, the line drawings and the parts lists make a liar out of me. Maybe they built it that way, but without drivers in the bottom cell.

But, I'm prepared to be wrong.

I'd say it's a 3012; as well, the unmarked box near the tailgate looks just like the battery box for the MCP's that I take care of ; perfect size for two 12V batteries & their charger; which would be enough for a 3012. I would guess that in place of the standard AC charger it would have a 12V to 24V converter. The energy conversion losses to run an 12VDC to 120VAC inverter, then use that to power the 120VAC to 24VDC battery charger - nahh, too much.

Yeah, this would be great on the road. Unfortunately, here in NC, state law forbids the use of a siren on a vehicle by anyone other than a proper Public Safety individual; Police, Fire, EMS, etc. BUT!! an 'air horn' is OK, Hmmmm, iPod output to the Ultravoice's mic input, oh yes!!

Air horn.
Steam Whistle/train whistle/Diaphone sounds
"Hey, you in the ugly truck!! Yeah, you!!! Stop signs with the white borders are NOT optional!"
"Why are you driving slow in the left lane and I'm passing you on the right?"
"HANG UP THE PHONE AND DRIVE!!!!!!!!!!!!!"
Sounds of jake-brake & tires squealing....

Is there an audio equivalent of 'mooning' someone?


[quote]What's also interesting about this setup is that there is not a dummy cell in the stack. For a Modulator to work right, there needs to be a bottom half and top half facing each other to make the correct 360 exponential horn shape. This unit's bottom cell has the doors, making me think it would have active drivers in there. None of the cells are reversed to face each other, so that bottom cell is either inactive, as it should be (yet is has the driver doors), or it is just inefficiently beaming sound straight down.[/quote]