Hi I have a tuning problem with a P Bass ('63) which is driving me crazy. Other strings are fine, but the A String harmonics (produced over the 12 fret and 5th fret) are way sharp compared to the open string note ... so far sharp that I cannot use these harmonics to help me tune the bass. This problem is not related to the frets ... but to the characteristic of the A string itself and I notice the same problem with flats (TI) and round wounds (Rotosound, Fender). The bass does have a fair amount of truss rod slap on certain notes when the strings are played hard, but its hard to see this would causing this problem. Only other thing I can think of is it might be down to the resonance of the timber? I've been using a Peterson softstrobe app on my iPad and realise that its a big ask for an old P bass to play in tune all over the neck ... totally understand this. But this A string thing is weird and I wonder if others have noticed it ... been able to live with it ... or whatever. Also, pretty sure it not how the string is springing over the nut (witness point) ... as I have had different nut in the bass trying that angle ... problem seems in the string and how it vibrates (and produces harmonics). Any ideas folks?