Dwain gave you a very good run down on the various aspects of wound strings. In the end, if you experiment with different strings, it all depends on the sound you like. It is interesting to note (pun not intended) that the sound you hear as a player is not necessarily the sound someone listening to you play hears. Strum you dulcimer strings a few times and listen. Then ask someone to strum the strings while you sit about ten feet away from the dulcimer. Does it sound the same? Is there a difference? When you play you hear the sound from above and maybe slightly behind the dulcimer. When listen from ten feet away you hear the sound from a lateral position. Another aspect is volume which drives me crazy with our dulcimer group. Folks play to hear themselves, but five feet away your can hardly hear them. Put some force in to that strumming, I tell them. It might work for a quarter of one verse of a song.

Ken
"The dulcimer sings a sweet song."

 

The choice of string and string size depends on the instrument you have, the voice quality it is capable of, the voice quality you want, the tuning scheme you want for its strings, and the vibrating string length ( aka VSL, the distance between the nut and the saddle).

There are various tools to help get the right string set. But there are some surprises to be gained in unconventional string choices.

No wonder you're getting brain swell!

But if you furnish more details than listed above, luthiers and musicians can give some guidance. Regarding what you did list, here's a luthier's experience with them:

80/20 bronze refers to the mixture of copper and tin in a the windings of a wound string. It can be initially bright, even bell-like, but quickly loses its brilliance. But that will depend on the tension of the string, which is determined by the VSL and the pitch it is tuned to.

Phosphor Bronze is a warm wound string that holds its warmth and brilliance over a range of tensions, though higher tension will bring out its brilliance too.

Flat-top wound strings have the winding flattened to relieve the 'zing' during quick traverses from note to note without raising the finger. Some people do not appreciate the slight loss of brilliance that results with flattening the tops of the round winding wire.

Nickel wound strings are quite a bit more brilliant than 8/20 or Phosphor Bronze.

Plain steel wire is used for higher pitches and/or to control the finger pressure needed to firmly fret the string's note. Steel strings can be chosen by gauge (measured in thousandths of an inch, in my experience), to define the tension at which a string is operating when tuned to a designated pitch.

As for XS and XT strings, that seems to be a D'Addario innovation that alters the warmth of the string with coatings. Here is a video illustrating the difference between XS and XT strings.

As for string gauge, or diameter,  these choices usually involve the pitches you want the strings tuned to (the tuning scheme), the instrument's VSL, the warmth vs brilliance you want, and the optimum finger pressure for fretting notes. All those will depend, also, on the qualities of the music instrument you are concerned about.

Hope that helps!

updated by @dwain-wilder: 05/15/25 05:16:59PM

Only one of my current dulcimers uses a wound bass string. I have always preferred a nickel wound string when a wound string is called for.

A string is a string is a string. You don't need to pay too much attention to the instrument type on the string package:::just the gauge, and end style. Just make sure it is long enough to fit your dulcimer.

You can purchase sets that include typical sizes for the dulcimer or individual strings of the correct size and style, plain or wound. Years ago before I started getting a friend to make my strings from bulk music wire, I purchased all ball end strings in groups of 3 of each of the sizes my instruments used. It is easy to cut the ball end out of the loop, and have a loop left if you do not need the ball end. That way you do not need an inventory of both loop end and ball end in each size.

The strothers string gauge is a good place to start to help determine the gauge you need. List the VSL and the note to which you wish to tune. Some think it tends to run a bit light on the recommendations and suggest going to a slightly heavier string.  https://www.strothers.com/string_choice.html

Juststrings.com is going out of business. Another source I have used is  https://www.stringsandbeyond.com/aboutus.html

I hope this helps. Thanks for asking. That is the way to learn when you have questions.

Hey kids, here we go again. I think this musical journey is starting to hurt my head. any one out there know of a good website or link about strings.  Looks like there's 80/20 bronze, phosphor bronze, nickel bronze,  flat top, nickel wound, XS plain steel, XT plain steel, and so on. Then of course we have gauge sizes.  I think my brain is starting to swell