Dominant Chord?

[mhoward]

I'm trying to understand the chord harmony study in the Scales Over Chords book, page 45. They say the Dominant Chord (V) is most active when played as a Dom7, because it is formed by adding a minor 3rd interval over a basic triad. OK, I follow that. But then they say "This produces a flat seventh: a tone that is non-diatonic to the scale established by the key signature. The addition of this one non-diatonic tone creates a tonality that demands resolution back to the Tonic which is the point of rest."

 

Why do they call this 4th tone a flat seventh? It's not flat, is it? A diatonic 7th chord is composed of the 1, 3, 5, and 7th degrees of the key, isn't it?

 

Then they say that the Dom7th is built with a tritone interval, "three whole steps, between the third and seventh degrees." I thought a tritone was the interval between the 4th and the 7th degrees. What's going on here?

[CBLjazz]

I'm trying to understand the chord harmony study in the Scales Over Chords book, page 45. They say the Dominant Chord (V) is most active when played as a Dom7, because it is formed by adding a minor 3rd interval over a basic triad. OK, I follow that. But then they say " This produces a flat seventh : a tone that is non-diatonic to the scale established by the key signature. The addition of this one non-diatonic tone creates a tonality that demands resolution back to the Tonic which is the point of rest." Why do they call this 4th tone a flat seventh? It's not flat, is it? A diatonic 7th chord is composed of the 1, 3, 5, and 7th degrees of the key, isn't it? Then they say that the Dom7th is built with a tritone interval, "three whole steps, between the third and seventh degrees." I thought a tritone was the interval between the 4th and the 7th degrees. What's going on here?

 

Dominant 7s

The reason they say that the dominant 7th chord has a flat 7th is because chords are named according to the root and it's key.

 

G7 is the Dominant 7 of C major and

because the Dominant 7th chord is built

7- 1 3 5 b7 which would be G, B, D, F when G is the root. They are saying the "F" is the flat 7 because in the key of G- F is normally sharp. The key of G has 1 sharp, F#.

 

Tritones

I think you should think of tritones and any other interval as the relationship between 2 notes and not as "between the 4th and whatever degrees" because the distance of notes within a chord changes based on the chord type.

A tritone is always the distance of 6 half steps or 3 whole steps.

In a dominant 7 chord there IS a tritone between the 3rd and 7th degrees because the distance between these 2 notes is 6 half steps or 3 whole steps.

In a G7 chord the distance between the 3rd (B) and the 7th (F) is 6 half steps or 3 whole steps.

You can also think of a tritone as 6 frets on the guitar.

On the 1st string the 3rd (B) is on the 7th fret and the 7th (F) above it is on the 13th fret.

 

There is a mistake in your book though... When it said that the 7th in the dominant 7th chord is not diatonic to the key which is why it wants to resolve. That is wrong. In the key of C, G would be the dominant chord and F would be the 7th. F is diatonic to C- that's why the book is wrong.

 

The dominant chord has strong gravity to resolve to the 1 chord because of the tritone that exists in the domant chord. The tritone is an unstable interval that wants to resolve to a stable interval. Here's an example of that concept in action.... this will be difficult to explain in words but I'll try.

 

Play the open 2nd string and the note on the 1st string, 1st fret together- simultaneously. This is the tritone that exists in a G7 chord- the B (2nd string open) and the F (first string, first fret).

Now if you play that repeatedly your ear wants to hear the resolution...

The resolution- now play the 2nd string, 1st fret and the 1st string open. Play both of these notes simultaneously- this is a major 3rd interval which is very stable. That major 3rd interval is the C (2nd string, 1st fret) and E (1st string open) that is in a C major chord.

 

The tritone wants to resolve to the major 3rd that is why the domimant pulls to the tonic. G7 pulls to C (in the key of C).

 

Does that answer your questions?

[gennation]

The M7 thing is, like a V7-I progression in C Major, the G7 has the note B as it's M3 "leading" to the Root of the I chord, C. B is the M3 of G7, but it's also the M7 of C.

 

There's a few things here, the V7-I progression takes the "Leading-tone" of the Major scale, B, and 'leads' you to the Root of the I chord, or the Tonic of the Key. THis is a very important part of Western Music.

 

The b7 of the G7 (F) also leads down to the E which is the M3 of C, the I chord...or it can move up to G, the 5th of the I chord, C. So, that b7 helps the leading-tone, B->C, sound even stronger.

 

The M3 AND the b7 of the G7 (B and F) set up the Tritone CB was talking about. These set up Tension. These in turn are a major part of the V7 "resolving" to the I chord. This is called a "cadence". The V7->I cadence is called the Perfect Cadence. There are many other cadences, but only one Perfect Cadence.

 

Now, the term "dominant". It's used pretty wide open talking about "7th" type chords. But, the term "Dominant" is in relation to it's FUNCTION...not so much the type of chord it is. But as time has when on...and the functioning Dom7/V7 chord containing the leading-tone...most people just call a 7th chords a Dominant chord by default...but in reality, it's only Dominant when it functions as a Dominant chord...or the V7.

[1001gear]

Somebody correct me if I'm wrong.

With a C fundamental, Bb is the natural 7th. The B natural in C Ionian is therefore a raised seventh. Raised to lead more emphatically to the tonic.

I want to further detail the inexorable correlation of harmonic function to the lowly overtone series but I'm glazing over.

[mhoward]

Dominant 7s The reason they say that the dominant 7th chord has a flat 7th is because chords are named according to the root and it's key. G7 is the Dominant 7 of C major and because the Dominant 7th chord is built 7- 1 3 5 b7 which would be G, B, D, F when G is the root. They are saying the "F" is the flat 7 because in the key of G- F is normally sharp. The key of G has 1 sharp, F#.

 

I see my error... I read about construction of a major 7th chord, and didn't notice that dominant 7th was different. So the dom7 adds a minor third interval over the basic triad, whereas the major7 adds a major 3rd. That explains the b7, which was the source of my confusion. Thanks for your quick replies.

[CBLjazz]

Somebody correct me if I'm wrong. With a C fundamental, Bb is the natural 7th. The B natural in C Ionian is therefore a raised seventh. Raised to lead more emphatically to the tonic. I want to further detail the inexorable correlation of harmonic function to the lowly overtone series but I'm glazing over.

 

The B is natural in the key of C. Theorists don't consider the B natural in the key of C to be a raised 7th.

Harmonically the B is the 3rd in the G chord (the dominant or V) that wants to resolve up a half step (one fret) to the C.

[1001gear]

 

Well like I said, in the overtone series it's a Bb. The first few partials comprise a major triad and a flat 7th. The major 7th doesn't occur till way further up. The psychology of harmonic tendency and resolution is based on those relationships. This is where it gets foggy for me. Maybe Genn or Pops can detail this stuff .

[CBLjazz]

I don't know that stuff. I feel asleep during acoustics class.

[1001gear]

Me too. I think it's the key though.

[gennation]

Well like I said, in the overtone series it's a Bb. The first few partials comprise a major triad and a flat 7th. The major 7th doesn't occur till way further up. The psychology of harmonic tendency and resolution is based on those relationships. This is where it gets foggy for me. Maybe Genn or Pops can detail this stuff .

 

I'm not as familiar with the overtones series, but even in that don't they still LABEL the Bb (in reference to C) as a b7 "interval"? Their are MANY concepts related to music, butit seems even the hard core ones still use the basic Interval Names as points of reference...and commonly compare things to the Major Scale.

 

Now, this need to be considered when learning any new concept/system.

 

So, while Bb is the "7th note of the overtone series", it's not necessarily the "7th note of our Western, or Diatonic Major, Scale".

 

Again, I'm not very familiar with the overtone series, But I know it's directly related to frequency overtones. Kind of scientific if you will and can be understood using an oscilloscope. But the counting of the notes and the Interval labeling are two different things I think. Maybe someone else has a better explanation...that's just my quick look at it.

[1001gear]

I suppose technically all scales are contrivances to facilitate systemizing sound into western music. I just recall a class where it was being discussed. Made perfect sense at the time. Going to have to visit Pythagoras I guess.