String change weirdness!

[vindibona1]

I have had my Ibanez BTB 1825 for a year or two and have had D'Addario NYXL.45-130" on it almost the whole time. At least a year. I had a pack of the same strings in the drawer and have a special event I'm playing at tonight. So, on Wednesday I changed the old with a new set of the same strings. The string change went without any issues. But when I got it tuned and began to play it the action felt high. Was the neck relief different? I changed strings one at a time so I can maintain similar neck tension throughout the change. My string height gauge said that the action was, on the two lower strings at least 2/64ths higher and at least 1/64th higher on the D and A strings! Neck relief seemed to be where I like it, just low enough so there is no string buzz. The setup was perfect before the string change and left me scratching my head.

So of course, I re-adjusted the string height, but am perplexed as to how the height changed requiring a whole new setup? I did have to re-intonate three strings that were showing to be a bit flat at the 12th. What could have possibly happened that required a new setup???

 

[Dlew919]

First thing I thought was a different gauge but you said that it was the same strings.

It’s a head scratcher …

 

[Clark W]

I have had my Ibanez BTB 1825 for a year or two and have had D'Addario NYXL.45-130" on it almost the whole time. At least a year. I had a pack of the same strings in the drawer and have a special event I'm playing at tonight. So, on Wednesday I changed the old with a new set of the same strings. The string change went without any issues. But when I got it tuned and began to play it the action felt high. Was the neck relief different? I changed strings one at a time so I can maintain similar neck tension throughout the change. My string height gauge said that the action was, on the two lower strings at least 2/64ths higher and at least 1/64th higher on the D and A strings! Neck relief seemed to be where I like it, just low enough so there is no string buzz. The setup was perfect before the string change and left me scratching my head.

So of course, I re-adjusted the string height, but am perplexed as to how the height changed requiring a whole new setup? I did have to re-intonate three strings that were showing to be a bit flat at the 12th. What could have possibly happened that required a new setup???

Tension is what happened.

One set is new, one set has been strung up and under tension for a year or more. The year old set no longer has the same tension as a new set of the same gauge/strings. So when you put the new set on, you now put more tension on the neck pulling it, which of course makes string height rise.

 

[Turnaround]

Tension is what happened.

One set is new, one set has been strung up and under tension for a year or more. The year old set no longer has the same tension as a new set of the same gauge/strings. So when you put the new set on, you now put more tension on the neck pulling it, which of course makes string height rise.

This is NOT the case. The tension will be the same, or if different because of very old strings it will be a negligible difference.

The first question is - did you set the witness points at the nut and bridge. Failing to do so can result in the symptoms you describe and intonation issues.

 

[Tim Skaggs]

Yah, as @Turnaround said, the strings that needed intonation set are likely coming over the bridge saddles in an arching curve but they should be making a sharp angle at the point where they contact the saddle. The arching curve will make the action higher and the intonation wonky. And also what @Turnaround said; old strings don’t lose tension simply from wear. They lose tension from temp changes and stretching, but you add it back with the tuning keys.

 

[SunByrne]

Tension is what happened.

One set is new, one set has been strung up and under tension for a year or more. The year old set no longer has the same tension as a new set of the same gauge/strings. So when you put the new set on, you now put more tension on the neck pulling it, which of course makes string height rise.

Basic physics tells you this cannot be true. If strings change tension, they change pitch. So if the string could not maintain tension, you’d be unable to keep your bass in tune.

Also, what would be mechanically happening to the string that would cause this in the first place? Tension is a function of pitch and unit weight, i.e., the amount of string mass per inch. For this to happen, the string would have to lose (or gain) mass. Unless big flakes of metal are constantly coming off the strings, there’s no way you’re losing enough mass to noticeably alter the tension. As for gaining mass, sure, strings pick up a little oil and dirt from fingers, but there’s no way that’s enough to meaningfully change string mass.

 

[vindibona1]

Tension is what happened.

One set is new, one set has been strung up and under tension for a year or more. The year old set no longer has the same tension as a new set of the same gauge/strings. So when you put the new set on, you now put more tension on the neck pulling it, which of course makes string height rise.

I disagree. Tension would result in a change of neck relief, not string height.

This is NOT the case. The tension will be the same, or if different because of very old strings it will be a negligible difference.

The first question is - did you set the witness points at the nut and bridge. Failing to do so can result in the symptoms you describe and intonation issues.

Witness points? I didn't think of that. I'll go do that and see if that changes anything. If so, I'll probably have to refine the setup.
I did gig it Friday night and it played great. But the intonation change is something I didn't expect to have to adjust. The I-1825 has a zero fret, so nothing much could change there- and didn't. Nor did setting the witness point at the bridge.

I still wonder why I experienced the string height difference? It really doesn't matter as everything is great after the adjustments.

 

[thefaceofbass]

I'm not familiar with the particulars of the bridge on your Ibanez BTB, but I've had numerous basses where saddle height or forward/back position easily changed during a restring. Vintage style Fender bridges will do it every time unless you've used loctite or some other method to keep your settings from drifting.

 

[Turnaround]

The I-1825 has a zero fret, so nothing much could change there- and didn't. Nor did setting the witness point at the bridge.

Did you set the witness points at the zero fret as well?

 

[Dirk Diggler]

Good call on the zero fret setting the witness point.
Same concept, check everything.