I'm still planning to post on chord progressions, when I have a long enough block of time to do so--should be soon.

But for now, I'll tie up a few loose ends and address a few questions that have been raised.

I did see a book that used the terminology X minor major seventh chord, written Xmin(maj7). Means the same thing as X minor sharp seventh--Xmin#7.

I don't know if the 11th and 13th chords I talked about earlier lack certain notes because that's the definition of the chord or because the book I was looking at was accomodating the fact that guitars offer a maximum of six different notes. I'm sure there are texts that have the info, for those who are curious. The main point in my mentioning those chords was that they (and 9th chords) are built on 7th chords. Sometimes a plain old 7th chord is a reasonable substitution for a 9th, 11th, or 13th chord. Other times it's not satisfactory--trust your ear.

Now, about that #8 note:

It's significant in terms of an octave (A to A, C to C, Db to Db, etc.)--our word octave stems from the Latin word for eight. "Do-re-mi-etc." back to "do" comprises eight notes.

In 9th, 11th, & 13th chords, you're obviously going to pass 8 on your way to those numbers, so you've got to have a #8 note.

BUT--in terms of major, minor, seventh, suspended, diminished, etc. chords, it's just a repeat of note #1. Another way to look at a C scale is this:

  C  D  E  F  G  A  B  C  D  E  F  G  A  B  C  D  etc.
  1  2  3  4  5  6  7  1  2  3  4  5  6  7  1  2  etc.

Sometimes you'll see the second course labeled "1a, 2a," etc. and the third course "1b, 2b," etc. This is because they are different notes--that second C is a higher pitch than the first C. But for our purposes, we're concerned about the essential character of its being a C, rather than a D or an E.

In an earlier post, I mentioned that a typical guitar F chord has the notes F, C, F, A, C, F. The important thing is that the F major chord has the notes F, A, & C (notes 1, 3, & 5 of the F scale) and ONLY those notes. Whether it has one, or two, or three F notes (or A notes or C notes) doesn't really matter. It's still an F major chord. You could call the F notes in that chord 1, 8, & 15, which is technically correct, but for our purposes irrelevant. Look at the seven different notes of the scale, look at the definition of the chord in question, and select notes with the correct note name. For most chords, there is no need to count above 7.

Some mention has been made of the fact that there are no notes between B & C or between E & F, while there is a note (black piano key) between A & B, C & D, etc. Well, here's the explanation:

Because.

I'm sure there's a history of music text that explains how and why this came to be, but in terms of practical application, there is no more definitive nor satisfying answer than--because. That's the way it is, it ain't gonna change, we just gotta learn it and deal with it.

Now, about that V or V7 chord:

When a three chord song is said to have the I, IV, & V chords, those numbers are often meant in a general sense. It might have a I, I7, IV, IV7, IVm, V, V7--the point is it has a I-something chord, a IV-something chord, and a V-something chord.

In a great many songs found in folk, Irish, bluegrass, country, etc. music, it really doesn't matter much whether it's a V or a V7. I notice that bluegrassers hardly ever use seventh chords, whereas folksingers use them a fair amount. You can even find that one book use the V chord in a given song where the next book uses a V7. So often, either one is fine, and it comes down to personal preference.

Sometimes, using the seventh chord is significant. Play I--I7--IV (in C, C--C7--F), and you'll see that it's just not the same as playing I--I--IV. And in blues, often the IV7 is used instead of IV, and sometimes even I7 instead of I. Other blues patterns use V7 in the main phrasing, but use a V as a turnaround between verses. These uses of seventh vs. major chords are part of the character we associate with blues music, so it can matter which one we use.

These distinctions tend to become easier to pick up with experience.