Tuning the trussrod is not an option because it is a single action trussrod. It will tighten, and thus remove relief. It only turns one way. If I try to loosen it, the nut will come off and it will not add relief. I would be happy to show you what happens. If it were a matter of just tuning the trussrod, I would not have to contact the manufacturer and the bass would have been back to you much sooner. I have plenty of repair work to keep me busy and the rent paid, so I have no need to create any extra work for myself.
I’ll save you a little Googling. The purpose of the trussrod is to counteract the tension of the strings. The main issue with the bass is that it doesn’t not have enough relief (bow). The way to handle this issue is to add relief into it by loosening the truss rod, and letting the strings add relief to the neck. With a dual action truss rod, this is an easy adjustment since it will create a counter tension to add relief. But since this is a single action truss rod, you can only loosen it a certain amount. This single action truss rod has a nut at the top that is attached to a threaded end of the truss rod that can be tightened to compress the neck and take out relief. But when it is loosened, it will take compression off the neck, but it if you continue to loosen it, the nut at the top will get so loose that it will not do anything. Imagine that you ran a bolt through a sponge, and fastened it at the other end with a nut. As you tighten the nut, the sponge will compress and become more stiff. When you loosen the nut, it will decompress the sponge and make it more floppy with each turn. But once the sponge is fully decompressed, the nut will not have any effect on the sponge and eventually will come off the end of the bolt. So, you can add relief by loosening a single action trussrod, provided there is enough tension in the strings to create it. Unfortunately, the strings that are on there are not providing enough tension to do that. What we need to do to solve this is to add some bow to the neck, and with the current strings and truss rod, it is not possible.
You may be able to keep the same gauge, provided that they create more tension. You can look at various strings and gauges to see how many pounds of tension they provide. Sometimes a string with a lower gauge can provide more tension that strings of a higher gauge depending on materials, core, windings, etc. Also keep in mind that a higher tension string will give a more stiffer feel.
I see 3 solutions to this problem.
- Add more string tension to create relief. A different type of string may solve it. Tuning to a higher pitch, such as F may solve it as well.
- Physically remove the back bow with a clamp. With no string tension, the neck probably has some back bow. It can be placed on clamps for a few days, to remove the backbow. Unfortunately, I cannot do that at the shop, and would have to send it out.
- Compensate for the lack of relief by filing frets. You can shave down the frets at the lower frets to compensate for the lack of relief. A PLEK machine can do that, and it will do a scan to see if that is possible first. I have seen the machine to miracles on guitars with twisted necks...
