For those of you in the Los Angeles area, there are several Modulator 6024s at the Exxon Mobil refinery in Torrance. They use a different attack tone than any other modulator Ive seen. Also theyre tested on the first Wednesday of the month at 11am.
Locations... Unfortunately these are the only two I have found but here they are:
https://goo.gl/maps/g6qHYWP9Bgr
https://goo.gl/maps/NUyrEmQvmHP2
Youtube clips:
https://youtu.be/aj90FzACTaA
https://youtu.be/lbohPUNGqi4