The white Queen infamously told Alice "The rule is, jam to-morrow and jam yesterday – but never jam to-day."
So here's a Jam from yestidday.

Rob Wassserman plays an assortment of bass instruments. Below is the intro to his Wikipedia entry:

Rob Wasserman (April 1, 1952 – June 29, 2016)[1] was an American composer and bass player. A Grammy Award and NEA grant winner, he played and recorded with a wide variety of musicians including Bob Weir, Bruce Cockburn, Elvis Costello, Ani di Franco, Jerry Garcia, David Grisman, Stéphane Grappelli, Rickie Lee Jones, Van Morrison, Aaron Neville, Lou Reed, Pete Seeger, Jules Shear, Brian Wilson, Chris Whitley, Neil Young, Jackson Browne, Laurie Anderson, Stephen Perkins, Banyan, Mystic Knights of the Oingo Boingo, and Ratdog.[2][3][4]

He is best known for his own work on the trilogy of albums, Solo, Duets, and Trios.

I suspect that all the Duets and Trios started life as jams, though they may have been refined before recording. This is the duets album, though loading You Tube and entering Rob Wasserman Duets in it's search bar will generate more. His Trios album is also worth a listen.