What happened ?(neck has gone dead flat)

[Byzcat]

So, I had new strings put on my bass- went from a fairly light gauge roundwounds to a heavier gauge of flats, had to adjust my truss rod (I like minimal relief).

All was well for a couple of days, and just now, I picked up my bass and...

Fret buzz. I fretted it at the first and twenty-fourth frets, and there is no relief at all.

I would have expected that the neck would have become more bowed, not less. I do have a lot of temperature changes in my room (fall in New England, keeping the window open unless it gets too chilly) but though I've had to tune the instrument a lot, I've never needed to adjust the truss rod.

What could have caused this?

[goes off to loosen truss rod a bit]

[Jools4001]

The guage of a string is not the only factor in the tension that is required to bring it up to tune. Thicker does not neccesarily mean more tension, the string construction has a lot to contribute as well.

I don't use flats but there is some received wisdom that says flats tend to be lower tension than roundwounds, but as always there are exceptions.

Do as you are doing, adjust the truss rod to suit the actual effect the new strings are having rather than the theoretical effect...it may take a few days to get it right

BTW, Once the truss rod is 'balanced' with whatever strings the bass is wearing it's humidity changes rather than temperature changes that will be the main factor that the neck reacts to.

[Byzcat]

Well, I'm using Fender flats (50-100), the G and A are the only strings that are heavier-gauge. And they do feel looser, except for the G.

I'd had a (technically correct term for a female canine) of a time getting the thing adjusted after the string change- I started with way too much relief.

'Course, I do know that brand-new strings have a bit of stretching to do, unless you're playing a KXK K.K. Downing signature series guitar (and even then, I'm dubious), so maybe the strings relaxed a bit and allowed the neck to relax as well.

And with the old strings, I never needed to adjust the truss rod at all (of course, I've only had the bass three months).

[ByF]

Originally Posted by Jools4001

I don't use flats but there is some received wisdom that says flats tend to be lower tension than roundwounds, but as always there are exceptions.

Actually, I do use flats and the conventional wisdom is that flats tend to be higher tension, with the exception of TI Jazz Flats.

Anyhow, to the OP--the neck may need to be tweaked a couple of times before it settles in to the new tension.

Ed

[unclejane]

All my basses do this so I've just learned to live with it. My setups tend to be right on the gnat's a$$ at all times - I prefer a very low action and a nearly flat fingerboard.

So even small changes due to changes in temperature will be noticeable. I.e. the weather is getting cooler here and the other day when I picked up my L2000 it was completely "fretting out" all the way out to the third "fret" position. I don't play it anymore after getting my Carvin, so it had sat since the middle of summer.

Even my carvin's relief flattens out microscopically when the weather cools off. I figure it's the truss rod, being metal it must shorten/lengthen more than the wood does with changes in temp. Like I said my other basses do the exact same thing.

If you normally run a higher action, this is less noticeable. You'll just notice the action is a little less firm in cold weather than when it's warm.

I just keep a screwdriver and allen wrenches around and tweak as needed....

LS