Try this:
Oscillator
– 1: Pulse wave. Set pulse width to a little less than full Square.
– 2: Sine wave. Mix a bit in just to fatten up the pulse wave sound.
– 3: Pulse wave. Full square, once octave below. This should be quite than Osc 1, but loud enough to get some of that low growl in there.
Unison: 4 voices, a little width, pretty heavy detune.
Filter: Lowpass, 24 dB. Bring Cutoff down about halfway to get a pretty round sound. Then modulate it with…
LFO: Fast saw wave. This will create a repeating-note effect while also creating a quick decaying filter shape. Play around with the LFO Amount and Filter Cutoff until you get the right sound.