I have bought a second hand acoustic guitar. The nut with the slots for strings is showing in the following picture. The slots are very deep. It looks weird. Should I file the nut to make it lower? Is there a standard slot depth for acoustic guitars? How about for classical guitars? I have search in this forum and found no information. I am a beginner, any help will be highly appreciated. Thank you.

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  • How does the guitar play? Any problems with fret buzz? Do you like the action? Jun 1, 2020 at 21:59
  • Thanks for asking. This guitar has very nice and big sound. So far no fret buzz, except little buzz on low E 3rd fret, when played really hard. Probably because the 3rd fret metal strip is low. Don't know how to repair it. I'll just leave it. I adjusted the truss rod yesterday, maybe it hasn't got to its equilibrium yet. I am not used to such narrow fretboard (44mm on 1st fret!), comparing with my classical guitar 52mm on 1st fret. The 1st fret width 37mm is too wide for me. Is it normal? The action is low. Like it. The strings are too light, 1st and 2nd are too thin, hurting my fingers. Jun 2, 2020 at 9:56
  • 2
    You may well find that more hurt fingers will be the result of heavier gauge strings, as they will need to be tighter.
    – Tim
    Jun 2, 2020 at 12:32

2 Answers 2


Weird? What's weird about it? The height of the top of the nut really has no bearing on anything except aesthetics. And that doesn't look too bad. Perhaps a previous player has deepened the slots to make it easier to fret at that end of the fingerboard.

As long as the strings don't rattle or buzz on the lower few frets, it'll be fine. If you really want to file some off the top, do so, but the majority of us would rather spend that time playing the guitar.

  • Thank your Tim! Fortunately, no buzz on the lower few frets. Yes, it’s mainly aesthetics. I have a classical guitar for a long time and the slots depth is quite shallow, probably I am used to that depth. But I doubt a little bit that it may have some negative effects on the sound quality. Thanks a lot for your insight. Jun 2, 2020 at 9:05
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    As an instrument maker who has built and reworked many many nuts, I want to underscore the physics of this. Unless the nut is so high that you run into it with your fingers, it doesn't matter how high it is: the only critical parameter is the height of the action, and as long as your strings don't buzz, you're good. Jun 2, 2020 at 12:17
  • @ScottWallace, well said. Thanks a lot for your opinion. Jun 2, 2020 at 13:20

Having a low action at the nut is important on a (steel string, non-classical) acoustic guitar, because the string tension is higher than on a classical guitar, making barre chords etc harder. Of course you don't want the action so low that it causes string buzzes, but you say

Fortunately, no buzz on the lower few frets.

Taking that into consideration, my reaction on seeing your guitar is: I'm jealous that you got a guitar that someone took the time to set up properly! Many acoustic guitars are sold with a ridiculously high action at the nut and really needing a proper set-up, including a nut filing.

I'd also think that filing down the top is likely to make the nut look worse. If you really don't like the look, you might consider getting a new nut and filing down the base of the nut to achieve more-or-less the right action, then filing the slots just where necessary to get each string exactly right (or getting a good guitar tech to do it for you). But honestly, things like nut and saddle height are all about getting the instrument to play right.

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    thanks. If there is no negative effect on sound quality, I'll leave the nut that way. After I bought it, the action was too high for me. I filed the saddle to lower the action. I am the 3rd owner of this beautiful guitar. You are right. In order to set it up properly one needs good tools. Beside that, perhaps intelligence. It is relatively easy with classical guitars for they don't have truss rod. I hope I can fully set it up well. Thanks again for insight and cheers. Jun 2, 2020 at 10:11

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