Not long ago I replied to another thread with a similar sound, so I just copy-pasted it here:
The first example is a classic bass sound commonly found in Future Garage music. If you like such basses, take a look at that genre!
Normally 1 or 2 saw oscillators are used, but in this case I think it's either a saw-square wavetable where they've blended in the square a little, or faded in extra square oscillators above the saw oscillators.
Anyway, 2 oscillatos, of which the second one is an octave higher and blended in. As I said, either use a wavetable and blend in a square, or add 2 more oscillators with squares.
Set the unison voices to 3 or 4. Adjust the detune until you get a thick and steady bass sound.
Add a very steep lowpassfilter, and lowpass it a lot until you only have a few harmonics left. Add some resonance by taste to boost the harmonics a bit, making the sound thicker.
Add some saturation to make it sound meaner.
You can also highpass the sound a little to remove the fundamental, and apply another layer with a sinewave without the detune if you want a steadier bass (otherwise the bass will pulsate, but sometimes that suits better, and then you can just use multiband compression to even out the fundamental).
The other example is pretty similar, but with further unison voices and a little softer detune.
Sometimes it's nice to let the keyboard track the detune so you can control it.
