A Dobro is a namebrand of a particular type of guitar called a ” resonator guitar ” just like ” Chlorox ” is a name brand of bleach. Much like ” Chlorox ” and some other name brands sometimes a brand becomes so popular and well known that its name is synonymous with the product. That is the case for ” Dobro ” it is what most people know it best as, and as far as I know that is what most people still call resonator guitars, ” Dobro ” including me much of the time.
A resonator guitar is still a guitar, it has a lot in common with the tradition steel string guitar, but it also has some differences that gives it, its own distinctive sound. It does have six strings, but most people don’t play them like they would other guitars. There are two variations of the resonator guitar, one is called a square neck, where the strings are really high off of the fret board, these are always played with a slide ( something mostly made of glass or steel that is placed on the strings to give it a distinctive sound ) The ” square neck ” are played with the body of the guitar facing up, and you usually see them in Bluegrass music.The other variation is called a ” round neck ” and the strings are much closer to the fret board like a traditional guitar, these can be played more like a traditional guitar, and still use a slide as well. These are often played and held like a traditional guitar, These are often used in Blues type music. The resonator guitar like its name states, has a resonator built into the body of the guitar, they usually look like a big metal circular disc in the front of the guitar body, this is what helps to give the ” Dobro ” it’s signature sound. If you look at some pictures of them as compared to regular guitars it becomes easy to see the difference, when you see the big metal resonator.
Another key difference is how it is tuned, even though it has the same number of strings as a regular traditional guitar, the resonator guitars are usually tuned differently, one common way of tuning it is in what is called an ” open G ” where when the strings are ” open ” ( the strings are not being held down or touched ) when it is strummed it is in a G chord. This is how they are commonly tuned to play a ” squareneck ” Dobro, with a slide. Find more info on dobro at musicians friend.