The wikipedia article on double stops is mostly just a big argument, sadly. While it's true the term was borrowed from bowed instruments, it's typical use can simply mean two note struck at the same time (in the most simple interpretation). Some folks will get picky about it and say the notes must be "Plucked" and not picked in order to qualify. Some would say one note can be picked and the other plucked. Some say the notes can't be adjacent in order to fit the term. uggh.
Without making it too complex, you can think of double stops as just two notes played at once such as two notes, vertical to each other in a pentatonic scale. They can be struck, plucked, pinched, whatever, IMHO
It's not physics, i's guitar playing after all. Precision has value, but only so far as it doesn't interfere with progress IMHO. Getting too picky about terms like double stop, seems like a good way to make a simple technique in to something more complex than it needs to be
In broad terms, the two note power chord could be thought of as a double stop of sorts. It's two notes struck in a given scale after all. Though they are not vertical to each other. Then again, once you hit the B string, you have a one fret off set either way, so just add one half step and you get a power chord
The classical technique that it's derived from, often involves a pretty strong mute. Though it's different from pizzicato but that's another topic. Anyhoo, I've written a very long bit trying to make something more simple. I hope I haven't done the opposite
Todd
You are at GuitarMasterClass.net
Don't miss today's
free lick. Plus all our lessons are packed with
free content!