Donald Fagan, Ruby Baby , Anthony Jackson, Outtro, sub low F#

[LonF]

Hi all,

In the outtro of Ruby Baby there's a low, sub F# Bass note every 4th measure for 4 beats. Is it Anthony using an octave pedal or a synth? Maybe a bass-heavy E string F#?

I have to know! My friends think I am hearing things.

Thanks!