We will offer you a basic "recipe" for developing bass sounds with the JU-06. There are tons of textures out there; so please note these are only some starting points; it's up to you to create unique bass sounds for your music.
SQUARE/PULSE or SAW or both combined
Add some SUB (even up to max.) and sometimes NOISE
RANGE: 8 or 16
You could modulate the PWM with the LFO.
HPF - most of the times at 0
VCF - adjust FREQ to taste; add some RES if needed
ENV, LFO, KYBD - adjust to taste
Attack 0; Delay (1-6); Sustain (0-7); Release (0-5)
According to taste
None or to according to taste (mostly chorus I)