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While trying to correctly intonate guitar(which was problematic, you can see my last question why), I noticed a strange thing and I don't really know if it is normal or not. I've searched about it everywhere and found nothing, so I hope you can help me.

I was fretting 12th fret to check my intonation(But it does this not only on 12th fret, even on open string) and was looking at the tuner same time. I felt that I held my guitar in a bad position(it was slipping) and I corrected it and suddenly there was a different reading on my tuner. Then I did this test: I held my guitar in normal position(not classical) and started to angle it towards the floor while plucking the string and the note was getting flatter. Then I did the same but tilted it towards the ceiling and note got sharper. So my tuning depends on the position the guitar is held and even a little tilt changes it.

What can be cause of this and is it just my problem or guitars do that in general? (I don't have any other electrics to test this)

Edit: I made a video demonstration here (youtube)

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  • I don‘t think that it‘s the position of the guitar in the room. It must be the angle of your finger that changes the tension of the strings when you turn your guitar upside down.
    – Albrecht Hügli
    Commented Feb 9, 2019 at 11:37
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    It does this on the open string as well. So I don't think that's a problem.
    – Brsgamer
    Commented Feb 9, 2019 at 11:41
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    And you are playing with an amplifier?
    – Albrecht Hügli
    Commented Feb 9, 2019 at 12:18
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    Looking back at you last question, where you swapped a shim - could be that the neck isn't tight.
    – Tetsujin
    Commented Feb 9, 2019 at 12:38
  • I'm directly plugged into an audio interface, going into logic pro's tuner. as far as i can hear, it does this while unplugged as well. As for the shim, it did this even before the shim.
    – Brsgamer
    Commented Feb 9, 2019 at 13:01

1 Answer 1

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The neck of your guitar is not perfectly rigid, but it bends.

Another possible factor is how well is the neck screwed into the body. If it's even a little loose, it could affect the tuning.

When you put it face down, gravity pulls it down, increasing the curvature of the neck, shortening the distance from bridge to nut and decreasing the tension of the strings. With looser strings the pitch goes down.

And when you put it face up, gravity pulls the neck straighter, increasing the distance between nut and bridge and increasing the tension of the strings. With the strings being pulled harder the pitch goes up.

In intermediate positions, depending on where the force of gravity pulls the neck, you get intermediate levels of string tension and therefore of pitch.

People sometimes grab the headstock with one hand while playing, and push it back and forth to do a tremolo effect. Jimi Hendrix was famous for that, among many others. That's based on the same principle.

Now, this happens to every instrument, but if the neck is rigid enough, the effect is negligible.

Perhaps you can make things better by slightly tightening the truss rod. If the truss rod is too loose, tightening it a bit will not change much the curvature of the neck, but will make it more rigid, and therefore more resistant to these changes in pitch.

And you should also check to make sure that the screws that fasten the neck to the body are holding strong.

(Here's an example of neck bending if the above description wasn't clear enough)

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  • Yes, i have seen many times how Hendrix does this. I've done it myself also, but i don't think this level of pitch shifting is normal. What you said makes a lot of sense, but Truss rod is as tight as it gets, it's just won't turn anymore without a very significant force and I'm afraid that will break it. (Why is it so tight you might ask? Because neck was curved and that was the only way to make it straighter)
    – Brsgamer
    Commented Feb 9, 2019 at 14:49
  • It looks like that guitar's neck is a bit too flexible than it should . It could be just that it came from a piece of wood that it happened to be more flexible than average. And the fact that the neck was so curved that you had to tighten the truss rod all the way just to make it straight, that's consistent with the idea of the wood itself being not rigid enough to start with. The only other thing that I can think of is that the neck might be bolted to the body in a loose way -- i.e. besides the neck itself bending, the connection to the body should be tightened too.
    – MMazzon
    Commented Feb 9, 2019 at 14:59
  • It's a maple neck with a rosewood fretboard. But the guitar is like 18 years old, so that might be the cause of the flexible wood. I have bolted the neck to the body as hard as I could, but I will still check if it can be tightened more.
    – Brsgamer
    Commented Feb 9, 2019 at 15:03
  • I don't think that age alone causes this. Wood from one tree can be different from another, age differently, react differently to humidity and temperature over the years. Maybe you just got a guitar where the fretboard woods are more flexible than average. And maybe the installation of the truss rod was also slightly defective, and it didn't strengthen and stiffen the neck as much as it should have. It's probably a combination of all these factors, who knows which more and which less. When I've had guitars like that, I tuned them in the same position in which I played them, and it was OK...
    – MMazzon
    Commented Feb 9, 2019 at 16:00
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    Well... This guitar had a lot of problems and somehow managed to fixed most of them. I don't think this is fixable. I'll just have to play in the same exact position every time. I'm using 11 gauge strings btw. In E Standard tuning. I've been trying to get a new guitar, but I can't at this time. Either that or I'll go to moon and play there without gravity haha.
    – Brsgamer
    Commented Feb 9, 2019 at 18:49

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