I'm playing blues in dropped d tuning (DADGBe) while using the open DAD as a "root" chord, and playing lots of "F" and "G" notes on the low and hi d Strings and lots of "c" and "d" notes on the "a" string. What key does that put me in? What would be a 4th above that key? I'm looking to get a blues harp and was told that you get one a 4th above the key I'm playing in. sorry about my ignorance here, I guess it's time to start learning the basics of notes and keys etc... what's the best place to start there? Every time I open a theory book I am immediately lost.