You can also see the video - along with an accompanying article - in DJ Mag's weekly e-zine, DJ Weekly.
While it's named after Dub, you've probably heard a Dub Siren used in all kinds of music and DJ sets. In this video, Point Blank instructor Jonny Miller demos a hardware dub siren, and then shows how to make one in Ableton Live using Analog, Overdrive and Ping Pong Delay. The tutorial explains the process from scratch and ends with a nicely set-up Instrument Rack, complete with macros that mirror hardware dub sirens. Check it out: