I built this bass years ago and it has had this issue the hole time. I had even posted in here before under G String Buzz but now I do not think it is the frets. I just went through and re-leveled the frets again and it did not help much and that is when I really noticed something. I hope this makes since but the G string sounds out of tune when played open. It gets that wow wow sound but it is only one string being played. When I first noticed this I thought I may have hit the D string as well and was getting that in my ears when tunning. So I made sure I mutted all other strings and it still does it. Has anyone had something like this happen to them? Not real sure where to start. Could the nut angle not be correct and it is causing this or the break angle at the bridge not enough? It still has the string buzz around the 9th-13th frets but I think there is something else going on here. Also not real sure this could cause it but the neck is thin but I used the large U channel trus rod from Stew Mac for this reason. I am wondering if the neck could be flexing when played and cause this? The trus rod holds the neck alignment just fine as far as I can tell. If this helps, I have my neck relief set to the 6th fret clearence just enough so a business card will slid smoothly between the bottom of the string and the 6th fret, when fretting the 1st and 15th frets. I hope someone can help with this becuase it drives me crazy to have such a great sounding and playing bass (minus G string issues).