It's the "Jump!" sound, and it's accurate enough to start phasing against the original recording. I didn't play the actual riff, the keyboard doesn't have the range to do the correct voicing to begin with, but I do play some notes around the appropriate octaves and chords. For examples of the sound: http://www.synthtopia.com/content/2009/06/30/van-halen-jump-demo-oberheim-obx-a/