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Old 12-11-2018, 05:34 PM
imc2111 imc2111 is offline
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Default Why would a warped neck make the guitar sound out of tune?

I once had a guitar that had a warped neck. It sounded out of tune, even if it was properly tuned with a strobe tuner.

I took it to a good luthier and he mentioned that the neck was warped and this was causing the intonation problem. He trued the neck and problem solved, the guitar then sounded in tune. I never understood why the warped neck caused that issue though.
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Old 12-11-2018, 06:13 PM
musicman1951 musicman1951 is offline
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I'm not sure, but I assume that when the neck is warped it shortens the distance from the higher frets to the nut.
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Old 12-11-2018, 06:17 PM
PiousDevil PiousDevil is offline
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Originally Posted by musicman1951 View Post
I'm not sure, but I assume that when the neck is warped it shortens the distance from the higher frets to the nut.


This. A warped neck effectively changes the scale of the instrument, setting every fret off it’s intended tuning just a bit.
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Old 12-12-2018, 09:24 AM
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devellis devellis is offline
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A warped neck might also selectively alter the distance from the resting string position to the fret, depending on how it's warped. If this happens, then some notes will get stretched a bit more when fretted and will consequently sound sharp, relative to different strings or the same string fretted elsewhere on the neck.

Surprisingly, I've played some instruments with twisted necks that played remarkably well. A twist, although visually disturbing, doesn't necessarily upset the geometry of the strings relative to the frets all that much. Some old instruments in particular can show this -- a noticeable twist that really has little if any impact on intonation or playability.

If you think about it, every string essentially follows a one-dimensional path from nut to saddle. What's happening to either side of it really doesn't matter all that much. If the geometry along that path is good (i.e., the space from string to each fret top is as it should be and the total length of the vibrating string is correct), all is well. A twisted neck, while obviously not ideal, can meet that criterion. A warped neck, on the other hand can get both the string height too variable from fret to fret and the scale length too short for the fret placement. The result is the instrument playing out of tune.
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Old 12-13-2018, 05:42 AM
imc2111 imc2111 is offline
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Originally Posted by devellis View Post
A warped neck might also selectively alter the distance from the resting string position to the fret, depending on how it's warped. If this happens, then some notes will get stretched a bit more when fretted and will consequently sound sharp, relative to different strings or the same string fretted elsewhere on the neck.

Surprisingly, I've played some instruments with twisted necks that played remarkably well. A twist, although visually disturbing, doesn't necessarily upset the geometry of the strings relative to the frets all that much. Some old instruments in particular can show this -- a noticeable twist that really has little if any impact on intonation or playability.

If you think about it, every string essentially follows a one-dimensional path from nut to saddle. What's happening to either side of it really doesn't matter all that much. If the geometry along that path is good (i.e., the space from string to each fret top is as it should be and the total length of the vibrating string is correct), all is well. A twisted neck, while obviously not ideal, can meet that criterion. A warped neck, on the other hand can get both the string height too variable from fret to fret and the scale length too short for the fret placement. The result is the instrument playing out of tune.
What’s the difference between a twisted and a warped neck?
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Old 12-13-2018, 06:29 AM
ripdotcom ripdotcom is offline
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of course it would.
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Old 12-13-2018, 09:00 AM
robj144 robj144 is offline
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Originally Posted by imc2111 View Post
What’s the difference between a twisted and a warped neck?
Twisted can be described as a rotated neck with respect to the body. A warped neck is sort of like the neck is bent in a U either up or down.
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Old 12-13-2018, 09:06 AM
Wade Hampton Wade Hampton is offline
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Just to paraphrase what’s already been said, with a warped neck the string length has been physically shortened, but the frets remain in place for the original scale. So naturally the guitar becomes out of tune with itself.


whm
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Old 12-13-2018, 10:07 AM
Wade Hampton Wade Hampton is offline
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To which I’ll add, with those rare instances where the neck warps away from the bridge rather than towards it, the physical length of the strings has become longer, but the frets remain where they were and, again, the guitar is out of tune with itself.


whm
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Old 12-14-2018, 11:03 AM
imc2111 imc2111 is offline
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Originally Posted by Wade Hampton View Post
To which I’ll add, with those rare instances where the neck warps away from the bridge rather than towards it, the physical length of the strings has become longer, but the frets remain where they were and, again, the guitar is out of tune with itself.


whm
Thanks for your comments, Wade.

So how can someone fix a warped neck? Is steam necessary or what's the process?
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Old 12-15-2018, 09:33 AM
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Depending on how (and how much) it's warped, it may be possible to pull the frets, level the fretboard, and refret. A more drastic approach is to pull off the fretboard, level the neck itself (if there's room without interfering with the truss rod) and put on a new fretboard. If it's a gentle bend that's the problem, it may be possible to steam the neck and/or use some blocks and clamps to unbend it.

A twisted neck is one where the axis of the nut and saddle are different. You could have a twisted neck but still have strings running from end to end and each an equal distance from the fretboard at all points directly under the string, despite the twist. And the outside strings could maintain their proper distance from the edge of the surface below them. The strings aren't in the same plane as one another but each can be perfectly aligned and appropriately positioned relative to the surface of the neck. Of course, in practice, we don't set the strings to be the same distance from the fretboard along their entire length but the point is, a twisted neck doesn't render that -- or the more normal type of progressive spacing between string and fretboard -- impossible.

If you placed a razor-thin (or "string-thin") straight edge on the twisted neck along its length, it would be in full contact with the neck (assuming no frets, for the moment) for its full length. Now put that straight edge at an angle relative to the main axis of the neck and that wouldn't be true any longer. But stay parallel to the axis and the path from end to end is straight and the edge would remain in full contact all the way.

Imagine two blocks of wood with six holes drilled in each. Then imagine attaching strings through the holes, with about 25" of string length between the blocks. If you pulled the blocks away from each other until the strings were under enough tension to make them tight, they'd be kind of like the strings on a guitar (only without the guitar). Now, rotate one block (maintaining the string tension) so that its axis tilts by a few degrees. The strings will still all be straight and the spaces between them will be the same. If a fretboard under those strings had exactly the same twist as the stretched strings do, all the strings would be equidistant from the surface of that fretboard. This is essentially the situation with strings fixed at the nut and bridge when a fretboard develops a slight twist.

On the other hand, if the warping involves the neck bowing forward or backward, a straight string will inevitably and unalterably be closer to the surface of the neck at some points along its length than at others. You can't have a straight edge in full contact with the neck across its total length. Also, if the neck is bent to one side, the strings will be closer to the edge of the fretboard at some points than at others.

Although a twisted neck sounds like a major problem and can look pretty odd, it doesn't actually create the playing problems you might expect. Each individual string path can remain perfectly fine, even though the strings aren't in a flat plane. In a way, it's sort of like having an arched fingerboard with a nut and saddle that have the same curve in them. The strings aren't on the same plane with each other but each is in a perfectly straight line in the proper left-right orientation on the neck and the correct distance from the fingerboard beneath it. We're accustomed to arched fingerboards and don't even give them a thought. We're not used to twisted necks. But you could build a guitar with an intentionally twisted neck (perhaps with the bass edge of the neck rotated slightly away from the player to make playing barre chords more comfortable for the wrist) and it could work perfectly fine. This would work because the strings, individually, are essentially one-dimensional and thus indifferent to alterations that don't involve alterations in any direction other than along their length.
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Last edited by devellis; 12-15-2018 at 09:41 AM.
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