Hi,
Most 4 string bass player will probably tune their bass with the standard E A D G.
We are expose to players like Stanley Clarke and Victor Wooten who tuned their bass to
A D G C(tenor bass).
Some people wonder if they are to tune the G string up to C or how?
For me, I will buy the high C string from a 6 string pack and use it instead.
Another common tuning is the drop D - D A D G. Either you can manually tune down to D or fix in the Drop D hipshot.
Standard 5 string bass tuning is B E A D G, but you can also tune it to E A D G C (standard+tenor bass). Many bassists tune it this way as they wanted to do more melodic stuff on their bass like Steve Swallow and Dominique Di Piazza.
I also see some people tune their 5 string to A E A D G(Drop D concept).
Standard 6 string tuning is B E A D G C. You can also tune it E A D G C F or F# B E A D G.
I personally haven't tried it before but I'm sure it is nothing new.
Michael Manring Hyper Bass is another interesting instrument where the tuning is C F Bb Eb.
Different songs he will tune it differently. He is so scary.
You guys can read up more if you like.
Cheers