QUICK TIPS
Another way to recreate this sound is to create two MIDI tracks with the same data, then use a mallet or tuned percussion with a quick decay on one track and a pad on the other.
Any percussion or transient sound will work for the sampled layer. Why not try tambourines, pianos, guitar pick/mute sounds, or even a hi-hat for the sampled layer?
One of the core sonic components for the D-50 sound lies in its processing of the synthesiser’s layered signal through a thick chorus feeding a hall or chamber reverb.
While sawtooth pads are the most familiar layering element, try working with square/pulse waves or heavily filtered wavetables. The key is to use a low cutoff frequency to get a subdued sound.
Adding a very slight amount of slow vibrato to one oscillator in the pad layer is another way for you to add some thickness to the chorusing.