Defsoul is JB's producer name that he created for himself since GOT7 debut.
'Def' means cool and 'Soul' was inspired from one of his favorite artists Musiq Soulchild.
On the Christmas of 2016, JB created his own account on Soundcloud and released three of his songs Bad Habit,Sin and Holic.
In January 15 of 2017, DefSoul added in two more songs on his Soundcloud named Don't Worry and Lost.