Note on Steel Strings for Nylon String Guitar

 Update: For those not wanting to modify your guitar's saddle for steel intonation, Thomastik makes an excellent "hybrid" steel rope-core set -- KR116 is the model -- for classicals. It's not cheap ($35) but I use a set on our 1870s Tilton/Haynes guitar (click link to hear a sound clip) and love the sound. It's ideal for getting a small-body fingerpicking sound out of a nylon-intended guitar and the set mellows perfectly into a sweet sound after about a week of play. Back to the original post...

People are always trying to get away with putting steel strings on guitars meant (or rather, built) for nylon or gut strings. Aside from the setup problems this causes (nylon/gut strings tend to be setup for a slightly higher action and don't have compensated saddles) and the fact that the design won't favor the way steel strings resonate... there's also the issue that steel string tension is simply higher.

It can, however, be done safely... but you're not going to like the answer because, tension-wise, classical guitar strings run about 10-15 lbs on each string depending on the scale length used. That means that you really, really have to back the string gauges off and it definitely means you need to use an unwound G string to get a balanced set.

The easiest way to try this is to go out and buy an electric guitar set of "9s." The best (and most balanced) set for the job is the D'Addario EXL120BT pack and its gauges look like:

E - 40w
A - 30w
D - 22w 
G - 15
B - 12
E - 9

They all run about 13 lbs of tension on a long-scale guitar (25.5") tuned to pitch. Similar gauges to the ones above with wound strings of phosphor bronze or 80/20 are going to sound more typical to the ear.

The issue with steel strings of these gauges tuned to standard pitch is that they sound and feel... floppy! I know there are many electric guitar players that adore 9s (I can't stand 'em, myself... as they sound "thin" to my ears), but to your average acoustic player it will be frighteningly-easy to bend your notes out of tune by accident.

If you have a guitar with a shorter scale (24" like many 1900s-1920s parlors) you can probably get away with bumping the gauge up one notch as then the tension is comparable to a stiffer set of classical strings.

But what about "silk & steel?"

There is a constant idea that "silk & steel" strings are comparable, tension-wise, to something like a classical set. They're not. Average sets are anywhere from 1 2/3 to double the tension of a classical set.

So, forget that.


Jack said…
What about putting nylon strings on a guitar built for steel strings?
Anonymous said…
What does Willie Nelson use on his "Trigger" Martin classical guitar?
Jake Wildwood said…
1) Willie uses cheap Martin ball-end classical strings (as far as I know) but has an acoustic pup in there he puts through an electric guitar amp.

2) Nylon on steel strings = usually too quiet and will give you a dull, thuddy sound -- also needs a replacement saddle (non-compensated).

Some older instruments (20s tenor guitars, 20s/30s steel string guitars) are built light enough to sound decent with them, though. It's really case by case.
Unknown said…
I have 4 nylon string guitars and use John Pearse "Folk" strings made by Tomastek Infeld of Vienna. They are amazing. They sound like a hybrid between a steel and an nylon string guitar. I have never had any problem with them pulling on the bridge, whatsoever. It's my own little signature sound until the rest of the world discovers them.
Unknown said…
I wonder how the 9 - 40 method would work on my Martin 00-28c with 26.44" scale?

Here is the description of the John Pearse strings:

"The bass strings E, A, d are round wound on a nylon core for a big warm sound without ­distracting picking noises. The treble strings are flatwound nylon on a rope core and sound brighter than nylon strings. JOHN PEARSE is the perfect set for acoustic fingerstyle guitar."
Anonymous said…
Would the same apply to putting steel strings on a ukulele?
Unknown said…
The only thing I would ever try for a uke would be the John Pearse strings. Buy a set and do some experimenting.
Jake Wildwood said…
Carlos says via email:

I agree: the John Pearse Folkstrings have a unique sound. But the same manufacturer, Thomastik Infeld, also makes a low tension steelstring for classic guitars! The KF110 set from the Classic S series are nickelwound on steel and have the same tension as the nylon sets. Incredible but true!

Carlos Apers
Jake Wildwood said…
Steel strings of the proper gauges were actually made for uke in the old days!

That said, you'd really have to rework your intonation at the saddle to use any sort of steel on a uke without it going fiercely out of tune as you go up the neck.

Uke strings run about 25-40lb of tension for a whole set depending on brand.

A low G set would look like:

20w, 16, 13, 10 low to high to keep about 7-8lb of tension on each string.

If you were doing this on a banjo uke with a neck made for steel strings (often the full-banjo-style rim rather than the "California style" jo-ukes are) you would probably want to go:

30w, 22w, 18w, 13 in an ideal world, or swap in a 17 plain for the E.

My experience with stringing ukes with steel (I'm always tinkering) is that they sound god-awful.

This is because steel strings like a lot more top to get any bass response out of them while nylon/gut will get you tons of bass response on a fairly small surface.
Unknown said…
I have a Levin Model 118 that is supposed to handle both steel and nylon, or at least that is how it was originally marketed in the '60s. Not trusting that and having a really shallow neck angle I was in a pickle. Nylon buzzed on the frets, but, on the other hand, even silk and steel were too heavy for the top, making it deflect enormously. What I found that worked best was Thomastik Plectrum 10's. What I ended up with is an incredibly warm sounding and easy playing guitar, ideal for fingerpicking.
Anonymous said…
I acquired a steel string guitar in the past that had for lack of a better description "soft" feeling strings on it (low tension, easy bends, etc.). I'd compare them to classical strings in feel. What were/are they? Silverish in color as opposed to bronze, etc. I'll have to dig them out of the old string bag and pull one open to see what the core is. I recently tried some new Martin silk and steel thinking they'd be lower tension without actually doing the research and I was wrong as they actually seemed stiffer.