The rig in the back there is a GK 800RB (a punk classic!

) with a pair of aluminum-cone Hartke 4x10 cabs. I wonder if that sort of sound comes from pushing that rig to its limits with the Boost circuit? I've never really spent enough time with an 800RB (or any time at all with aluminum-cone Hartkes) to know for sure.
EDIT: Nevermind, there's a pedalboard back there, on the floor below his rig! Can anyone ID what's on there? Looks like a Boss tuner, something red, and a few other things...
I still can't figure out the bass, though. It looks like it could be a Yamaha BB, like mentioned by lurker, but it still seems off, especially because of that pickguard-ish thing around the knobs, that extends to the P-pickup.
Maybe it's a Yamaha bass I'm unfamiliar with. But that headstock does look like a Yamaha.