First time I've been able to do a close-up video of a Surry siren since December, not that there's much different about the system.
A random 465 hz did creep into the ambiance though - I think it's siren #38, which is unfortunate, as its location precludes an up-close video. Perhaps I'll try an ambiance from somewhere near it next test.
As usual, you can find more details in the video description.
Enjoy!
https://www.youtube.com/watch?v=at2Blzc6Ktk