Overdubbing a bass line?

[uberpsycho]

Hey, curiosity question here.

I've read about bassists overdubbing bass lines; Jamerson overdubbing an electric bass with a double bass, same for Herbie Flowers on "Walk on the Wild Side", though the one I'm really interested in is Paul McCartney's overdub on "While My Guitar Gently Weeps"

I'm wondering how was overdubbing usually done? How is it usually done now? What's the preferred method? How did they overdub McCartney on WMGGW?

Thanks for any help.

(Apologies if this is in the wrong forum. None of the others didn't seem to fit)

 

[Precision101]

We'll usually there is two tracks for bass where one is played over the other. Sometimes merged into one. I actually just recorded a version of roundabout today and there's is an overdubbed bass line in there too pretty fun stuff.