The Siren Board

This video is funny b/c the chic in this video is freaking out to the T-bolt right next their house going off. Very loud T-bolt!

http://vids.myspace.com/index.cfm?fusea ... d=20896972

Not sure if I am amused, or just trying to figure out what sound level setting its on the tbolt is on... sounds like the normal setting for about all thunder bolts heh.

In Valley Center (about fifteen miles from where I live) there is a Thunderbolt next to the middle school which sits right next to a house, and not only that, the horn sits right at the level of the upstairs bedroom window only a little more than twenty feet away.

md5 wrote:Not sure if I am amused, or just trying to figure out what sound level setting its on the tbolt is on... sounds like the normal setting for about all thunder bolts heh.

It could be my hearing but it sounds like a dual tone Thunderbolt to me, so 125dB @ 30m (100ft). Realistically, there isn't a 'volume' setting for the Thunderbolt. They want it as loud as it will go.

Justin wrote:

md5 wrote:Not sure if I am amused, or just trying to figure out what sound level setting its on the tbolt is on... sounds like the normal setting for about all thunder bolts heh.

It could be my hearing but it sounds like a dual tone Thunderbolt to me, so 125dB @ 30m (100ft). Realistically, there isn't a 'volume' setting for the Thunderbolt. They want it as loud as it will go.

Can't you control the volume by changing the spead of the blower motor, or messing with the blower belt? I've noticed some TBolts that appear to be softer than others. The one at the fire station on Pope Street here in Louisville appears to be one of those. You can walk from the Kentucky School for the Blind to that fire station in five minutes or less, but the siren sounds like it's a quarter of a mile away. In fact, the siren at Doss Highschool is about a quarter of a mile from Mom and Dad's house, but it sounds louder than the Pope Street siren, even from that distance.

There is one way you can 'quiet' a Thunderbolt, bar shutting it off; is to kill the blower and just let the rotor run. Though that'll create a high pitch not dissimilar to that of the Glassport Thunderbolt; though that discussion was a stone age ago, and my memory isn't that good.

Some Thunderbolts will be quieter than other ones because of the port ratio. Dual tones are quieter because of the smaller ports on the rotor where the air has less space to squeeze out; where as single tone Thunderbolts can allow more air to escape on queue, because of the much larger ports.

So a single tone Thunderbolt is 127dB @ 30m (100ft) and a dual tone Thunderbolt is 125dB @ 30m (100ft).
Here's a single tone rotor from Eric's site.
Can't seem to find a picture of the dual tone rotor, which is essentially two rows of rectangular ports.

If your at a distance however, atmospheric conditions will affect a sounds effectiveness at travelling long distances and is called "attenuation", measured in decibels.

Google Definitions wrote:Loss of signal power. Attenuation is typically measured in decibels per kilometer (dB/km) at a specific wavelength.

Generally, the best conditions are warm moist days.