Oscillator 2: Saw, one octave higher, and much quieter than Osc 1. We’re just adding a subtle higher layer here.
Noise: White noise. Also quieter than Osc 1.
Filter: 24 dB Lowpass. Turn the Cutoff down pretty far to start to get a nice round sound. If your synth has Drive, give that a boost. And turn on/up Key Tracking, making it strong enough that the higher notes are brighter than the lower notes. Then modulate the Cutoff with…
Filter Envelope: Quick Decay around 300 ms and a decent amount of modulation, to create a bright attack transient.
Ambience/Reverb: Very small size, but pretty wet, so it sounds like it’s in a basement.
Then gradually over time, turn up the Cutoff. The bass will get brighter and the Noise will be more noticeable.