setup problem

[fireball69696]

so here is it, i have a peavey bxp5 and i have a few problems i cant resolve.

a) when i adjust the truss rod, the upper side of the neck (where the B string is) is almost flat, but the lower side has a bow (towards the strings). when i press my strings at the 1st and 17th fret the string is more than 0.4mm (little more than 0.15") from the 7th fret
b) this bass has individual bridges [IMG ]http://www.bestbassgear.com/images/other/triple-lock-down.jpg[/IMG], and i cant set the saddle lower then 6/32" on the 17th fret (all strings) and i would like to set it to about 4/32" (any other advice is welcomed)
c) the bass has 2 soapbar pickups, the neck one is set to about the neck height, and the bridge is somewhat higher. this is a factory setting. do i need to make any adjustments to that?

and one question that is not related. what is the little hex screw in front of the saddle (you can see it in the pic i linked)?

please help

i use d'addario exl170 045-130 (if it matters at all)

thank you

 

[Rocky McD]

Remove the strings from the tuners, totally loosen the truss rod and check the natural condition of the the neck without any pressures on it. check the straightness, flatness and if there is any twist.

 

[Blue_Whistle88]

A little neck twist is norma. Both my current basses have a flatter curve on the bass side than on the treble side, as the treble strings are under slightly more tension. You can set up an instrument with this inherent imperfection and get it very playable. The issue sounds like you running out of downward adjustment on the saddles. I had that problem on a guitar and fixed it with a neck shim; there are plenty of instructions on how to do one on here, though I used a thick brass plate on mine because it was BAD.

Also try loosening the saddles to loosen the strings. That might be considered ignominous by some here, as it well affect intonation, but you can make the strings quite a lot tigher/looser using this method without affecting intonation significantly. You could try a little of that, then loosen the truss rod a bit so the strings aren't too high on the upper frets. Looser strings are easier to play, though loose and high versus tight and low is an argument based on personal preference.

But if you really want the strings lower and can't drop the action with the bridge saddles any more, definitely get a neck shim. It'll totally fix that problem, but make sure it's done well, preferably with a flat shim using thicker material rather than an angled shim. Angled shims allow for much more action-lowering using less material, but you lose total contact in the neck joint. If it's neck-thru or set neck, my other suggestion is your only option.

 

[edpal]

The issue sounds like you running out of downward adjustment on the saddles.

I've had that problem - fortunately, most bridge saddles are brass, despite what they are covered with (e.g. chrome). Particularly if you have round saddles the easier thing imo, rather than shimming the neck is to just file the underside of the saddles. You can quickly drop them a 1/16" of an inch and nobody will be the wiser. I have one bass where I simple foregoed the screws and carefully filed and sanded them so they could lay right on the bridge plate - talk about a full contact bridge.