Good stuff! Sounds like it actually has somewhat of a wind-down instead of just cutting off. It still probably winds up too fast and winds down too slow but it's great either way!
Here's the first of my two videos of the same siren. I was most pleased to hear it testing in attack. It was recorded in stereo on my S5IS, but I don't think it's available yet thanks to Youtube's processing.
Thanks again, Joe for finding this thing and letting me record it with you.
Something tells me that the bottom rotor is the eight-port rotor, considering it sucks most of the air in after the blower shuts off!
Also notice that the choppers seem to sustain their rotation for a short period after the wind-down, just before the blower shuts off; I think that the blades in there are slightly pitched. The sharpness of the tone is simply overwhelming!
Here's my second video. I used my crappy camera to get up close in hopes to hear more of the blower, while I left my nice camera set up to record from the tripod. The audio isn't great, but you can see more of the siren.