I know pretty much jack about music theory. I prefer learning things on my own, from references and experimentation over teachers, and I really need to get a better grip of music theory. Any advice?
Also, curious, why does the 7th note in a 7th chord (say, G7) seem to be the note a half-step dwon from the 7th note on that scale? Or am I just screwing up somehow?
You're not screwing it up... but you're not quite grasping seventh chords.
Our chord structure is called tertian, which means we build chords in thirds. We have two types of thirds, a major third (four frets on the guitar) and a minor third (three frets). If we want to build a four-note chord in thirds, we've got eight possibilities:
m3-m3-m3 gives you R-b3-b5-bb7, which is called a diminished seventh
m3-m3-M3 gives you R-b3-b7-b7, which is a half-diminished seventh, also known as a minor 7 b5
m3-M3-m3 gives you R-b3-5-b7, which is a minor seventh
m3-M3-M3 gives you R-b3-5-7, which is a minor/major seventh
M3-m3-m3 gives you R-3-5-b7, which is a domiant seventh
M3-m3-M3 gives you R-3-5-7, which is a major seventh
M3-M3-m3 gives you R-3-#5-7, which is a major seventh augmented
M3-M3-M3 gives you R-3-#5-R, which is an augmented triad.
Out of those eight possibilities, seven have four different notes, so all seven are "seventh" chords. But they all have different intervals inside them, so they need more specific names.
One of those possibilites - the dominant seventh - is the most common seventh chord. It's so common we often just call it "seventh", as in "G seventh"... when really the correct name is "G dominant seventh".
It's called a "dominant" seventh, because each note of a major scale has a technical name... and the fifth note is the "dominant". If you build thirds in a key without using accidentals (other than those found in the key signature) this is the ONLY scale step that ends up with a 1-3-5-b7 formula... hence the name "dominant seventh".
Guitar teacher offering lessons in Plainfield IL
I see I'm way out of my league.
Know any good music theory books that a person could order?
On a different forum, I've been more or less ordered to take lessons, and I plan on getting some wehn I can afford it, after I move next month. Otherwise, how are online lessons?
It's easy to think you're "out of your league," but the real answer is that you probably know more than you think! It's just a matter of getting a grasp on what you know. At the risk of sounding website-centric :wink:, we've got a whole slew of theory lessons here, and most of them are geared to the beginner...
https://www.guitarnoise.com/theory.php
Theory Without Tears is a good overview, while The Musical Genome Project, followed by The Power of Three and Building Additions (and Suspensions) is a great start to understanding chord construction.
Hope this helps.
Peace
Thanks.
