I have just purchased a second hand acoustic guitar: a Sigma 000MC-15E. The strings it came with tune fine but the high e string sounds noticeably out of tune even when played just at the third fret! After reading on here I'm thinking that the string gauge was maybe changed considerably from how it was setup in the factory and so new strings of a different gauge may fix it?

But why is only the high e string affected? Is it just more noticeable on high e? Should I get heavier or lighter strings? The high e goes flat when fretted, so I reckon a heavier gauge will bend the neck more lifting the strings off the fretboard and therefore make the strings sharper when played fretted?

3 Answers 3


You could try changing the strings - that particular guitar comes with D´Addario EXP16 Light (12-53) strings.

If that doesn't fix it, take it to a guitar technician for a full setup. If there are any issues, they should find (and hopefully fix) them.

  • 1
    I just put those exact strings on! 😊 The high e string is sounding good now and 12th harmonic and fret are the same so I'm very relieved😌, but now I'm interested in how that could happen? The action is lower now (so the strings before must have been a heavier gauge?) and causing some buzzing so I will adjust the truss rod and hopefully things will stay alright with the strings. Thanks Commented Aug 19, 2018 at 15:27
  • I think you're correct about the string gauge. A quick tighten with the truss rod would fix it. Don't do too much, though - if you think you're putting too much stress on it, take it to a technician. A snapped truss rod is no fun.
    – PeteCon
    Commented Aug 20, 2018 at 16:15
  • I turned it a bit really easily then it got lots more difficult to turn so I stopped, it didn't make much difference to the string height to be honest and as the only string buzzing was the low e I raised it slightly at the nut. Seems to be ok for now, don't want to risk anything with the truss rod! Commented Aug 21, 2018 at 22:29

I'm just speaking from a physics perspective, not an experience one. But I would think the thinner the gauge, the less the string will go flat as you go higher up. Imagine the resonant sine wave that a fundamental makes on the string as it vibrates up and down. The shorter the string (from being fretted), the more the thickness is going to want to prevent the string from bending (esp. at the ends), in effecting making the bump's shape that of a longer wave (i.e. of a lower pitch). If it were me, I'd try getting a thinner gauge and seeing if that does the trick. If you do the experiment, please let us know the result!

  • I'm not sure I fully understand you there but I've just changed the strings to the recommended ones and they sound as they should now. The action is lower though which I think means the previous strings were a heavier gauge. Not sure if it was just old strings cause the intonation issue or what as I've never had this problem before. The action is too low now though so I'll adjust the truss rod and hopefully the problem won't come back. Thanks Commented Aug 19, 2018 at 15:39

With a new guitar behaving like that, it ought to be straight back to the shop!

Try the 12th fret test first - the harmonics there ( on all strings) should be the same pitch exactly as the fretted 12th fret note. Of course, it could be as simple as the top string broke before you bought the guitar, and a different gauge one was put on. Ascertain what the correct gauge should be, and replace with that. Otherwise, back to the shop.

  • Ah, sorry I was very unclear there, I meant a new acoustic for me. Its a second hand guitar bought on eBay so I'm semi reluctant to send it back as I'd have to pay postage. That's why I'm tempted to just change strings and see if it improves. Thanks for your reply Commented Aug 18, 2018 at 9:04
  • Apart from 'return it', still try the rest of my answer, and also establish what gauge strings it normally has. The intonation should be set up for those.
    – Tim
    Commented Aug 18, 2018 at 9:53

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