I went and strung my 4 string bass .120-.55, and tune it B-E-A-D. The nut and the intonation are spot on, but I had to loosen the trus rod (coming from a dead flat straight neck approach, I find that... new). Fret buzz at 12th fret and some higher became a huge issue, so I rised the string at the bridge a little. Still, my D string (now, the thinest) is fret buzzing at the higher frets, and I don't wanto to rise it anymore. Should I do something wih the neck, maybe raise the relief a bit more? I'm lost here and could really apreciate your help. 