I’ve studied Aston’s playing for years and he was amazing imo, he played mainly a very early 70s jazz bass, I’ve read on a few occasions that the bridge cover still had the foam in (but I can’t verify that) , and he also used flatwounds and played close to the neck , my guess is he just used the neck pickup and bridge and tone off , when I use my jazzes I have the bridge pickup off and tone rolled back, I also just back off the neck pup just a touch and it gives me a fatter deeper sound