I just got a Warwick Thumb NT 6 and my b string is still sharp on the 12 and 24th fret but I cant tighten the screw anymore. What should i do? is it normal for the top few frets to be really out?
If your open string is in tune but your higher frets are out of tune it is the string length that is the problem.
If your bridge adjustment has moved to its full travel and intonation is still out, you should get a quick look at your truss rod adjustment, in case your neck is really out of whack, but aside from that you don't have many options. Have you run your bridge adjustment from one end to the other to check intonation?
I'm assuming you are of a level that you are not bending the string when you fret it at higher frets. It is sometimes difficult for beginners to avoid bending the string as the angle of your fingers at those frets is different.
Warwick specifically used to specify that tapered strings were required for their basses (especially on the B).
Some will note that tapered strings can also help with intonation. Doing research for tapered strings showed that DR Longnecks (tapered) strings actually have intonation issues so I suggest not picking those up to try and fix your current issue.
You can also try to push down on the B string at the saddle to see if you can get it to seat better.
You should also double check your truss rod as mentioned already.
I had the same issue with a guitar and those changes fixed it, it might also work for bass :
- Adjust the action : with a lower action, you need less "bending" on the string when fretting. It helped a bit but can be annoying if you like your current action.
- Change the strings gauge : this worked really well with my issue.