I had twiddled with the truss rod of my bass recently and it now seems to sound 'out'. While all the 5 strings were in tune, some of the fretted notes sounded very sharp but when I checked it with a tuner, it was spot on. So I tested playing the same notes on other frets to see if it was my ears playing tricks on me, and they sounded more in tune but still spot on when counterchecked with a tuner. Playing the same notes together sounded fine with no dissonance. One example is the F# (9th fret on A string) being "sharper" than the same note on 4th fret on D string. Both were spot on when tuned with a tuner. Can anyone tell what could be the problem? Was it the strings, the bridge, the nut, or just me? Also the low B string couldn't sustain long notes as well as other strings, and some notes sounded dull. Does it mean that it's dead?