E flat to C sharp, then you want to go for some feedback. Base chords are gonna be C sharp. A flat. A. F sharp...
If you really need a tutorial to help you figure out the chords to "Sonic Reducer" you may need more help than this, but Cheetah Chrome's instructional video for Gibson guitars has a kind of gormless charm anyhow:
And that guitar does sound cool. Can't beat a P-90.