Here's a crash course in what a string does for your sound and some examples of the categorical differences between strings. Next week, I'll give a few recommendations and defend my indefensible position.
On an acoustic instrument (acoustic guitars, mandolins, violins, etc.), the sound is produced by picking/strumming/bowing the string(s), which cause the whole instrument to vibrate. For example, the sound of an acoustic guitar is primarily heard through the vibration of the "top" (the side with the sound hole that faces the audience). So the point of acoustic strings is to get the whole instrument to vibrate in a musical way. In other words, the instrument itself is the "amplifier" that makes the notes project more loudly.
On an electric instrument (Strats and Les Pauls), or at least those with magnetic pickups, the point is to disrupt the magnetic field above the pickup, and the "notes" you hear are electromagnetic signals made louder by an amplifier. Put less scientifically, you aren't trying to make the instrument itself sound good on its own, you are trying to make a magnet sound good through an amp.
So a categorical difference between acoustic and electric strings comes down to magnets, or lack thereof. If you tried an experiment of putting acoustic strings on an electric guitar, it would sound thin and weak. Why? Typical acoustic strings (especially those of a nylon/classical guitar) aren't as magnetic, so electric pickups don't "hear" them vibrating. Alternatively, if you put electric strings on an acoustic guitar, it would again sound a little thin and tinny. Why? Typical electric strings aren't as resonant on their own, so they don't cause the entire instrument to vibrate as fully.
Nylon-string guitars (classical, flamenco, etc.) have strings with a core made of....nylon. Bass-side strings are wrapped with a thin wire, often a silver-plated alloy. The idea is to sound mellow but full. It's also not loud enough to compete with the volume of a larger ensemble, so...
Electric guitars and "western" acoustic guitars have strings with a core made of steel. Where acoustic steel-string instruments differ most from electric instruments is in the wrap wire. Acoustic guitars use a wrap wire made primarily of copper and zinc (it's vibrant and resonant). Electric instruments mostly use pure nickel or nickel-plated steel for the wrap wire (it's magnetic). There are other materials used on electrics as well, including chrome, stainless steel, and cobalt.
If you try string packs of differing gauges (e.g. .009-.042 vs. .011-.048), you'll likely notice an immediate difference in a few key areas. First, the tension of the strings will change. Assuming you keep the same tuning, you'll feel that thicker strings have more tension at pitch. This is what makes lighter strings feel "easier to play" and heavier strings feel "harder to play," especially for beginners. Less tension can mean less effort, so many shredders use light strings, and there's less hand fatigue with certain techniques like bending.
Second, you might hear a difference in tone and volume because a thicker string means more mass vibrating when you pluck it. On an acoustic, this means there is a stronger vibration transferring to the guitar body, and it makes the body vibrate more (more volume). Also, because the string is thicker, you might perceive fewer high frequency overtones in the note, which makes it sound "warmer." On an electric, more mass means more metal to disrupt the magnetic field of the pickup, and can slightly increase volume. Also similar to an acoustic, heavier strings may sound warmer. There are also some science-y things going on with tension and string vibration amplitude, but we'll save that for future discussion.
The construction of the string can change its sound quite a bit, too. Most strings today have a core wire shaped like a hexagon, but some still have a smooth round core wire. The wrap wire is most commonly a round wire, but can be a rectangular "ribbon" or other shape. Because these shapes affect the stiffness, density, and flexibility of a string, they affect its tone.
Most strings have a hex core with a round wrap. This gives stability with flexibility, so the string resonates well, has a balanced tone, lasts a long time, and is playable. These are what we commonly refer to as round wound.
Flatwound strings often have a round core and are easily identified by their wrap wire - a flat ribbon that makes the string very smooth to the touch. Jazz players like these because they last a really long time, can withstand high tensions, are stiff, and the tone is dark/warm.
A hybrid string is the half-round. It's a round wound string ground flat to look like a flatwound. It's flexible like a round wound, but the flat surface makes them less bright when playing fingerstyle.
Round core strings are a favorite of blues players and lovers of vintage electric guitars. While slightly less durable or stable than hex core strings, round cores feel more flexible and pliable, so they're nice for bending.
So what do you do with all this information? Next week, I'll put it all together into a few recommendations. Realize, though, that we guitarists are a fickle bunch of cork-sniffers, so the vast expanse of string choices laid out in front of you is a result of an infinite amount of personal preference that may or may not be rooted in scientific fact. Or tone, for that matter....
Comments will be approved before showing up.