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For the 2000th question on guitars - brass nuts are well thought of to enhance sustain on guitars, but surely that will only be the case with the open strings. Is there a secret that we need to know about?

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    The cynic in me wants it to be about as fundamentally sound as tying knots in your hifi cables... but I'm open to persuasion ;) I always thought the best way to improve sustain was turn your amp up more & stand facing it ;)
    – Tetsujin
    Dec 8, 2017 at 17:58
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    @Tetsujin - I thought tying knots produced a slight delay - oh no, to get that you need a really really long cable...
    – Tim
    Dec 8, 2017 at 18:05

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They are denser than bone, plastic, or other materials (copper is the second most dense common metal after lead). That increased mass leads to increased inertia at the top of the neck which increases the mechanical impedance at the nut which means energy is more slowly transferred from the string to the neck. Energy staying in the string longer means longer sustain.

In addition, the stiffness of brass is about three times the stiffness of Micarta (a common high-quality plastic nut material - e.g. Martin uses this on their high end guitars), and higher stiffness also leads to higher mechanical impedance. The influences of mass and stiffness on impedance are roughly equal.

I suspect the wood and thickness of the neck have much bigger effect than replacing something as small as a nut. This is because the mass and stiffness of the entire system are what is important. So increasing the stiffness or mass of one component does not necessarily increase the mass or stiffness of the whole system to a significant degree. Also, reducing transfer of energy to the neck means the vibrations of the neck are reduced so I would expect a minor tonal change.

Combined with the difficulty of cutting brass makes me think is a lot of trouble for not enough benefit. I'd go for a Fat Finger or other headstock mass device long before I'd go for a brass nut for sustain.

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  • Good answer, but once a string is fretted, any energy in it won't reach the nut, thus the reason for the question.
    – Tim
    Dec 8, 2017 at 18:45
  • @Tim Still increases the mass of the neck. Like an invisible fat finger that weighs a lot less. Are you looking for an answer for how brass nuts supposedly increase sustain (which is what I typed up) or actual proof and explanation that they do increase sustain?
    – Todd Wilcox
    Dec 8, 2017 at 18:47
  • I understand what you say. If that's the case, though, why haven't manufacturers built, say, more metal (=more mass/weight) into necks. I believe it's only open strings that are really affected for the better, but there's a certain hype for brass nuts. (Might be something to do with Winter !!) Changing the balance of guitars? weaker necks? (Doubt it). I'm interested in any and all reasons/theories. Dare I say it - Musical practice and theory...
    – Tim
    Dec 8, 2017 at 19:08
  • @Tim Sounds like a separate question but the answers can be summarized as tone and ergonomics. Many players find guitars made from larger amounts of denser woods to be uncomfortable, so adding mass for sustain is not a tradeoff everyone wants. And while it's debatable whether a brass nut noticeably affects sustain, it definitely affects tone, and not in a good way for most guitarists. Finally, why re-engineer for more sustain? I personally want less sustain in many situations. Some players have put foam blocks under their strings at the bridge to kill the sound more quickly.
    – Todd Wilcox
    Dec 8, 2017 at 19:11
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    @Tetsujin I would guess the woods used were stiffer and the workmanship was finer leading to much lower losses due to friction and other parasitic effects. But I am editing in stiffness as another factor in mechanical impedance. Thanks!
    – Todd Wilcox
    Dec 8, 2017 at 19:41
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I don't think it has anything to do with sustain (to be fair, there are no replacement parts that miraculously improve sustain). The idea is supposed to be that by having a nut material similar to the fret material (ie. metal), you get more tonal consistency between fretted and open notes. Compare a string anchored on nickel and steel to one anchored on brass and steel. I guess you would get the same consistency by making the frets out of bone...

Oh and for sustain, use a stiff pick, hit the strings hard, use lots of compression and distortion, high volume, and stand close to the speakers.

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    Some electric guitars appear to have inherently good sustain, even when not plugged in, but, yes, those are all contributory factors.
    – Tim
    Dec 9, 2017 at 10:20
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    You can get good sustain on an electric by turning up the volume and playing quietly. This works with light strings, thin pick, and no distortion or compression.
    – user39614
    Dec 9, 2017 at 11:58
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    @DavidBowling Also: a neat trick to get around triple the perceived sustain is to strike a note or a chord with the volume turned down, then raising it as it starts decaying.
    – user43681
    Dec 9, 2017 at 12:25

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