Download it from Adobe.
I posted a work-in-progress version of this track (which you will hear in the first few seconds of the video) on the development forum for the Doom project 'Back to Saturn X'. Tarnsman, who's working on quite a few maps for it, claimed it for one of his, so I finished it for him. :) With audio commentary. Sorry about the noise from my air-con unit, it was a warm one that day.