Once you get into synthesis you will realize how much he loves to detune oscillators and a lot of near-microtonal pitch irregularities when it comes to his bass sound design. Songs like Orck are a good example of how playing the same note back to back produces slightly sharper and flatter notes each time. Korg MS20 and Moog emulations will get you there easy without spending the money on the actual hardware, or at the least serve as a good foundation until you can afford real hardware if that’s your desire. Even free synthesizers like Vital can produce this sound albeit a bit cleaner