Stevie Wonder- It could be a mini moog or Arp odessy.
Musiq Soulchild-That could be anyone of the modern synths. You can get that from a Korg Tritons lead (gotta tweak it. Take the R&B lead and go into both ocillators filter pages and lower the cut off frequency)
Or take any of the rolands and build a patch using a sawtooth wave mixed with a sine wave and repeat the process as with the Korg Triton.(of course you have to get the right blend between sawtooth and sine wave.
lowering the cut off frequency (and using a low pass 24 db filter, if available) will give it that fat mellow sound.
You can also get pretty close by finding a nice unison bass patch and raising the pitch an octave. Good luck dawg
