Music by Kevin MacLeod. Available under the Creative Commons Attribution 3.0 Unported license. Download link: https://incompetech.com/music/royalty-free/index.html?isrc=USUAN1100309

MacLeod's description:

Genre: Jazz
Length: 1:05

Solo electric bass with added chorus effect. Nice, round and (of course) low. 014
ISRC: US-UAN-11-00309
Relaxed 2006