Awesome WPS-4008 Video

[acoustics101]

The lower tone of this unit will carry further and penetrate structures much better than a unit of higher tone, even if the higher tone unit has a higher SPL rating at 100 feet. It's not the performance at 100 feet that counts, but the performance at a mile or more.

[SirenMadness]

Some seriously low frequencies coming out of that thing. I'd like to see an ATI play those tones without overheating the voice coils.

Scary video, too! What a beast.

[ACAP10]

yeah you can (if you don't like the standard tones) order the Alternate tone set, what a creepy sound.

Ya I noticed on SafetyComs website that these were all in the standard tones. I really like the Alert version of this tone which I think is called Audible Alert, or All Clear( I think). It sounds more dual tone and soooooo much better than that crap Whelen uses for standard alert or wail now. Also the WPS-4008's are still on their website. I wonder if they do still sell them.

Where do you see the 4008 listed on Whelen's website?

[guitarguy1985]

The 4008 is 130db at 100' from what I have heard, compared to the 4004 which is listed as 129db on Whelen's web site. That is probably why they stopped making them, not enough increase in sound to justify the 4 extra drivers. Usually a two-fold increase in power results in a 3db increase.

[Alasiren1977]

yeah you can (if you don't like the standard tones) order the Alternate tone set, what a creepy sound.

Ya I noticed on SafetyComs website that these were all in the standard tones. I really like the Alert version of this tone which I think is called Audible Alert, or All Clear( I think). It sounds more dual tone and soooooo much better than that crap Whelen uses for standard alert or wail now. Also the WPS-4008's are still on their website. I wonder if they do still sell them.

Where do you see the 4008 listed on Whelen's website?

Its not on Whelens website rather SafetyCom's ( a reseller), here is the link:

http://www.safewarningsystems.com/produ ... _4000.html

**Open the PDF once on the page**.

[ACAP10]

Interesting find! Since it's not listed on Whelen's website I can't imagine it's made anymore, but maybe this safewarningsystem maintains Whelen products?

[acoustics101]

How low do the 4004 units go? Do they go as low or lower than the 4008 units? That is a lot more important than 1 dB less output. If they go lower they could actually carry further! You figure sound loss by x dB/1000 feet in addition to the inverse square law of 6 dB/doubling the distance. As the frequency decreases there is less loss as the distance increases, since factor x is frequency dependent.

As far as long range audibility is concerned it is all in achieving the best balance between choosing frequencies with the best propagation vs the Fletcher-Munson curves of equal loudness. You generally get diminishing returns below 200 Hz. Using frequencies over 500 Hz limit your long range propagation and penetration of structures. It mainly makes it sound louder only within the first few hundred feet. It's amazing how many sirens that use frequencies in this range, although it allows them to be built smaller and still achieve a high sPL rating at 100 feet.

I say again; there's a lot more to effective warning than simply achieving a high SPL at 100 feet.

The 4008 is 130db at 100' from what I have heard, compared to the 4004 which is listed as 129db on Whelen's web site. That is probably why they stopped making them, not enough increase in sound to justify the 4 extra drivers. Usually a two-fold increase in power results in a 3db increase.

[Alasiren1977]

The 4008 is 130db at 100' from what I have heard, compared to the 4004 which is listed as 129db on Whelen's web site. That is probably why they stopped making them, not enough increase in sound to justify the 4 extra drivers. Usually a two-fold increase in power results in a 3db increase.

Ya but according to the same website(Safetycom) that says the 4008 is 130dbc, they also say the the 4004 is only 126dbc.\, so i believe that the website is a little out of date.

After Whelen re-rated the 4004 to 129dbc, I am sure if the 4008 were still being made it would probably be re-rate to 133-133dbc.

[acoustics101]

Here's the point:

Let's say you have two units. One of the units, call it unit A, produces 130 dB at 100 feet at a frequency of 700 Hz while the other unit, call it unit B, produces 124 dB at 100 feet at a frequency of 350 Hz. At first glance you would say no contest, as unit A is 6 dB (four times the output) louder than unit B, that's conventional thinking-but wait!

Let's say the atmospheric absorption loss for the 700 Hz unit is 1 dB/1000 feet while the loss for the 350 Hz unit is 0.5 dB. These frequency dependent losses are, of course, in addition to the inverse square law loss of 6 dB/doubling the distance.

Figuring in distance, we get the following:

At 100 feet unit Unit A measures 130 db on axis while Unit B measures 124 dB

At 1000 feet unit A measures 108 dB on axis while unit B measures 103 dB

At 10,000 feet unit A measures 70 dB on axis while unit B measures 74 dB

What does this tell us? The unit of 6 dB less output of lower frequency is actually outperforming the louder unit of higher pitch at a distance-and is exceeding 70 dB at 10,000 feet! In addition to this, unit B would be less irritating to nearby ears while carrying further and being able to penetrate structures better. There is a lot more loss to a sound of high frequency penetrating a wall than that of a lower frequency.

[acoustics101]

The atmospheric absorption losses I figured are actually 2 dB/1000 feet for the 700 Hz unit and 1 dB/1000 feet for the 350 Hz unit, which are in line with my actual observations:

Let's say the atmospheric absorption loss for the 700 Hz unit is 1 dB/1000 feet while the loss for the 350 Hz unit is 0.5 dB. These frequency dependent losses are, of course, in addition to the inverse square law loss of 6 dB/doubling the distance.

Figuring in distance, we get the following:

At 100 feet unit Unit A measures 130 db on axis while Unit B measures 124 dB

At 1000 feet unit A measures 108 dB on axis while unit B measures 103 dB

At 10,000 feet unit A measures 70 dB on axis while unit B measures 74 dB