Recently, I spoke to a luthier about adjusting the truss rod. I told him that I adjusted the truss rod by "feel" and he scolded me right there on the spot. At first I didn't understand what he was talking about, but as he explained it to me, it all made sense. Everything starts with the relief, he said, all measurements of string height, etc. He mentioned that the relief is set ideally .014 - .016 thousandths of an inch (using a feeler gauge, straight edge, and at the 7th fret). The ONLY reason to tweak a truss rod, he explained is to get it back to this measurement. He further explained that any bass, if it has a good fret job, won't need any more or less relief to play "right" (and by that I mean with less fret buzz). Once this adjustment is set, all one has to do is raise or lower the strings to their own preference. His feeling is that there is an ideal numerical measurement that one should maintain (when weather changes, string gauges, etc), that will guarantee playability, rather than tweaking and adjusting the truss rod to "feel" b/c this is like chasing your tail, as all the adjustments are working off each other: Start with the relief, go from there. He also taught me that relief doesn't just effect concavity, etc. It also effects how high the frets are relative to the string in the UPPER register as well (i.e., the neck becomes more like a "U" rather than a J as I had once thought. So, I would argue from the above, statement, that a bass such as a Zon or Modulus doesn't need a TR, as the relief is dialed in from the get go utilizing the stiffness of the graphite neck (and flex characteristcs...) and it never moves. Not trying to start a flame war here, but I was wondering why everyone feels the need to adjust a truss rod on a graphite instrument when it's relief is already set up for you at that ideal measurement, where the string has enough room to vibrate, but also feels low enough to play comfortably (.014-.016") Seems to be two schools of thought: Adjust truss to where it feels good (hit and miss) or adjust truss rod to where a neck was designed to allow for a bass string to freely vibrate (a discrete measurement), and go from there. Using this method, I have been able to set up my Fender's very nicely (and much to my surprise, the necks stay put after the adjustment!) It is nice to know that I have a concrete measurement that I can always go back to if things get out of whack, and it is no longer voodoo.