Check me here...
Just upgraded the fretless neck on my Jazz copy. Same 34" scale same number of frets, went to jazz profile neck from P profile. Everything else constant: strings, tuners, bridge, etc... Strings are D'Addario XL Nickel .110's, my preferred gauge.
I've been slowly tensioning the truss rod over the last few days for my desired neck relief (Gary Willis method for those who might ask). Ultimately shimmed the neck just a little with a business card shim to lower the action.
After all this - here is where I stand:
-Neck relief is acceptable - pretty flat.
-Action is still higher than I desire (~4 to 4.5 mm at the 12th fret marker unfretted, about 2 to 2.5 mm at 7th fret marker when fretted at first fret and last fret. G string seems a little higher, but I haven't measured it.).
-Most importantly: String tension feels higher than I am accustomed to with these strings and some normal fretless techniques seem harder and it is more difficult to keep the string fingered against the board.
As far as I am aware; string tension is a function of string gauge, scale length, and pitch. Therefore truss-rod tension (i.e. too high) and neck shimming should not affect string tension once I have re-established proper tune (this bass usually lives at E-A-D-G and occasionally in D-A-D-G)
So, what gives? Why does this feel so weird? It stands to reason that higher string tension would require higher truss rod tension to maintain set-up parameters; am I wrong?
What else should I check and/or adjust? The truss-rod has approximately 2 full turns on it from when I received it and I assume it was de-tensioned as the seller cannot verify one or the other.
I'm stumped. At a point where I'm deciding whether to return to the original neck and sell this one off or get over my fear of continuing to tension the truss rod to try to lower the action.
Advice? Thoughts? Blatent Criticism? Recommendations to give up bass and take up needlepoint?