I replaced one nylon string (the G string) with a steel string. All the other strings are nylon. Is this okay?


The short answer is no. The tension of steel strings are way to much for a classical guitar to handle as it generally does not have a truss rod in the neck.


You'll probably get away with it on a temporary basis, but the tension isn't good for that guitar. Certainly, on a classical guitar, I wouldn't be putting all 6 on. One won't be too detrimental, but also the feel will be different - tighter, thinner - and certainly the sound will be different, so it's inappropriate for many reasons.


Steel strings are available in a wide range of gauges, which will need different levels of tension to play at any given pitch. For the most part, one may reduce the tension required to play a certain pitch by using a narrower string, but as metal strings get too loose, pitch stability suffers severely--much more so than with nylon strings.

The tension on a 13-gauge steel string (the "e'" from an heavy-gauge set or a "b" from a lighter set) would be about 9.7lbs. That's rather light as steel strings go, but probably not unplayable, and it should be safe on a nylon-string guitar (many nylon sets average slightly over 10lbs). I would not expect such a string to sound very good or offer a good playing experience when used in that fashion, but the tension should be low enough to avoid damaging anything. Using a 14 gauge string would increase tension to about 11.2lbs; that would probably improve playability, and would probably be safe, but would leave less safety margin against accidental over-tightening.

  • I've used .008" top, .010" second for the last 40+yrs, with no pitch problems – Tim Feb 12 '19 at 19:56
  • @Tim: A 13ga "g" string would fit right in with a set of 8's for an electric. Some people like 8's, and on a guitar with a suitable action height they can work just fine. Nylon guitars often have higher actions, however, and I would expect that a 13ga "g" would be right on the cusp of usability--much better than a 12ga, but noticeably worse than a 14ga. – supercat Feb 13 '19 at 16:28

Replacing one string with a steel one won't damage the guitar, but the playability of the guitar won't be good. Drive down to a local guitar store and buy a nylon replacement (or even a new full set).


(I'm sure I answered this before...)

Hey, it's your instrument; the guitar police won't break down your door for putting that string on your instrument. And it isn't like diesel in a gas engine; the damage won't be immediate and cause complete failure. The instrument will be playable until it won't.

But that's not what it's built for, and strings are cheap.

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