Why do steel string guitars sound more in tune than nylon strings?
 

I’ve noticed that my steel string guitars sound more “in tune” than my nylon string. As in the notes of the chords all over the neck sound more in harmony on the steel string. I was wondering if there is a reason for this and if it is normal?

Never noticed this. Maybe your particular guitar. Maybe fretting with too much pressure.

I will venture a wild guess. It might be due to the difference in the shape of the waveform. The softer tonality of the classical guitar may appear to the ear as less well-defined than steel strings.

Just a shot in the dark.

Nylon stringed guitars have far less string tension than steel strings, why most nylon string guitars have to truss rod. Maybe too much pressure when fretting or bending the strings slightly while playing.

I prefer some chordings on a steel more than a nylon. Not that a nylon is bad, just that steel can really ring. Vice versa? Can't say.

Too many unknowns to answer effectively: quality of your nylon-string guitar, quality and condition of strings (how old are they?), your tuning method, how you fret and pluck the strings (pick or fingers?). Assuming that all those unknowns are non-issues, I’d say that steel strings have a crisper and clearer sound vs. nylon and are maybe a little easier to tune precisely. Nylon strings seem a bit more variable to me. Some days, I’ll think it’s time to change strings, and the next day they’ll sound great. My first teacher used to insist that it’s good to loosen the strings and retune every so often (one at a time, not all at once, eh?).

Have you checked the tuning of each note?

Use a tuner (chromatic setting) to check every note on each string, on every fret. Check how much difference your fret pressure makes.
Obviously the ideal is that every note is in tune when using normal fret pressure - or at least your usual fret pressure, overall.

If not, then your guitar needs fixing. It might be something simple, like lowering the saddle or the nut to reduce the action (the further the strings have to travel to the fret, the more they are stretched), or it might be your whole neck is out, which could mean the frets are in the wrong place or (more likely) the bridge is in the wrong place.

None of this has any bearing on why certain chords might sound wrong. You might be more sensitive to equal temperament issues on a nylon-string, although that would be unusual- and I don't see how it would make sense. If anything, the brighter timbre of steel strings ought to make ET issues more pronounced (because the problem is caused by overtones being out of tune with each other).

My guess - if your guitar is well set up - is this is a fret pressure issue, because nylon strings have less tension, so you might be pressing them harder inadvertently (making some notes sharper than others).

There is an interesting physical side effect that happens in a vibrating string:


A string will vibrate at its resonant frequency and always be on pitch.

However, if you change the tension of the string, you obviously change that pitch.

One of the things we do while playing is hitting the string which applies more force, elastically stretching it and, thus, increasing the tension. So, the very act of plucking a string adds tension which raises the pitch.

If you place a tuner and pluck a string you can see this: pluck VERY hard and you will see the string is a tiny bit sharp and as the amplitude decays it comes back down to pitch.

Nylon has a very low strength and is much more prone to this.

Now, in a perfect world we would pluck the strings and never apply add any tension to them, then they would always be perfect every time.

Do people put steel strings on classical guitars? I thought that was a big no no?

Guitars intended for use with nylon strings are set up for the amount of force those strings apply to its structure. The guitar's strength and structure is optimized for that amount of force.

Steel strings brought to the same pitch as nylon strings apply a lot more force to the guitar's structure.

Very likely, a guitar strung (to pitch) with steel strings, where it was intended for nylon strings will warp its sound board or even lose its bridge or warp the neck. Unless the steel strings are considerably loosened or lighter.

This often is the result of age and/or quality of the strings. Nylon or synthetic strings often stretch non-uniformly and can develop deviation in the mass along the string length over time. That's what causes the pitch irregularities of synthetic strings compared to their steel counterparts. This can even be the result of non-uniform stretching of the string when they are installed.

Is it normal? Yes, for synthetic strings, but subject to the variables I mentioned. They can, and do, sound true to pitch in many cases. YMMV with synthetics.

I've never noticed that. Nylon strings take a while to stretch out though. Steel strings take about 5 minutes or so to "settle" in.

The OP is questioning two different types of guitars, not a classical strung with steel strings.

Can't prove it by me.

Mimmo Peruffo of Aquila Strings has a nice Youtube video showing his recommended way of pre-stretching his red synthetics to minimize the uneven stretching of the string that results from improper installation.

Aquilacord is one resource that has information relating to synthetic string mass distribution and its associated problems.

One of the ways that signal us to change strings is false intonation, and that's caused from the strings eventually stretching non-uniformly. Since the material is "plastic" by nature the string will always favor stretching in it's weakest area.