Theory question: Why is the 7th chord in key flatted?

[DesertTwang]

I just came across a YoutTube channel with instructional videos that look promising. I've only watched three so far, but from what I can tell, those three short lessons already have provided me with eye-opening insights to long-standing questions that no teacher ever told me.

I'm actually surprised these videos haven't accumulated more views.

Here is the first lesson in a series of ten that teaches going up the neck: https://www.youtube.com/watch?v=cbAkddz8J1c

In this lesson, the teacher explains that a key not only consists of 7 notes, but 7 chords as well. I think I get the concept behind it (harmonizing scales, correct?), but there is something that I'm confused about, and he doesn't explain it.

For the key of G, he says there are the following chords: G major, A minor, B minor, C major, D major, E minor and F major. I think I understand how these chords come to be -- we use only notes from the G scale to build them, and that's why some are major and some are minor -- but what I don't understand is why the seventh chord in the scale is flatted. There is no F in the G scale, so the resulting chord should be F# major, not F major. But the instructor makes it a point that it's flatted.

But why? Why does this one chord get an exemption from the rule of using only notes in the G scale?

[Brent Hahn]

Originally Posted by DesertTwang

For the key of G, he says there are the following chords: G major, A minor, B minor, C major, D major, E minor and F major.

Maybe the reason no teacher ever told you that is because it's wrong. The last chord is actually F# diminished.

[Silly Moustache]

... or even "half diminished - (m7b5):

The half diminished chord has a minor seventh (7) - it's a m7 chord wth a flat five (b5).

The diminished chord has a diminished seventh (dim7, °7). The minor 7th is again decreased by a semitone and hence is equivalent to a sixth (6) - only the theoretical approach is different.

More details on wikipedia - google "Half-diminished seventh chord"

[mr. beaumont]

It's confusing, it sounds like he's building on a previous lesson. He also says 8 chords and 8 notes...there's 7. I'd call it a slip of the tongue but he says it a bunch of times.

The F chord really doesn't belong there, it would be an F# half diminished. It's borrowed from the "dominant scale" or mixolydian...and it does commonly pop up in tunes in the key of G. Keep in mind, if you're improvising over it using the G major scale, hanging on an F# note is gonna sound pretty awful.

This guy looks like he's coming at it from a practical use sort of place for whatever music it is he plays. I tried watching a few other of his videos to see if I could figure out where exactly he was coming from, but I got bored quickly.

If you want to learn how to open up the neck and improvise, I wouldn't waste too much time with this guy's videos, they will be a source of much confusion.

[Sonics]

That harmonized scale doesn't sound quite right does it? But as suggested we don't know the context. That video had a previous part or parts.

Here's chord construction basics for The Major Scale explained in 20 (...or so minutes).

[frankmcr]

Originally Posted by DesertTwang

For the key of G, he says there are the following chords: G major, A minor, B minor, C major, D major, E minor and F major. I think I understand how these chords come to be -- we use only notes from the G scale to build them, and that's why some are major and some are minor -- but what I don't understand is why the seventh chord in the scale is flatted. There is no F in the G scale, so the resulting chord should be F# major, not F major. But the instructor makes it a point that it's flatted.

But why? Why does this one chord get an exemption from the rule of using only notes in the G scale?

It doesn't. The youtube guy is wrong. The "seventh chord" in this case is F# A C, which is called F# diminished (not F# major!).

[JonPR]

Originally Posted by DesertTwang

Here is the first lesson in a series of ten that teaches going up the neck: https://www.youtube.com/watch?v=cbAkddz8J1c

In this lesson, the teacher explains that a key not only consists of 7 notes, but 7 chords as well. I think I get the concept behind it (harmonizing scales, correct?), but there is something that I'm confused about, and he doesn't explain it.

For the key of G, he says there are the following chords: G major, A minor, B minor, C major, D major, E minor and F major. I think I understand how these chords come to be -- we use only notes from the G scale to build them, and that's why some are major and some are minor -- but what I don't understand is why the seventh chord in the scale is flatted. There is no F in the G scale, so the resulting chord should be F# major, not F major. But the instructor makes it a point that it's flatted.

But why? Why does this one chord get an exemption from the rule of using only notes in the G scale?

To be clear, he explains that he is flattening the F# note to make an F major chord.
And he also (partly) explains why: the F chord is "used more often", as the VII (or rather bVII) in the key of G.
IOW, songs in the key of G major - at least in rock music - use an F major chord very often, and never use the F#dim chord.

Where he cuts corners is he doesn't explain what the diatonic vii chord is, nor why that chord is rarely used.
The reason it's not used is three-fold:
(1) it's tricky to play;
(2) its three notes (F# A C) are all contained in the D7 chord, which is much easier (and sounds better and is more useful);
(3) nobody else (in rock, folk or country) uses it. So why would you?

The F#dim IS commonly used in jazz, where it gets two kinds of 7th:
F#m7b5 (half-diminished), F#Ø = F# A C E. Used as the ii chord in key of E minor. (I.e., in the sequence F#m7b5 - B7 - Em.)
F#dim7, F#º7 = F# A C Eb. From the vii degree of G harmonic minor, and used as a vii chord in keys of G minor and G major.
Both these chords are easier to play - and more useful - than the plain dim triad.

You also sometimes find dim7 chords used in blues, at least the jazzier kinds. You might also find the m7b5 chord used as a rootless dom9 chord (D9 without the D is F#m7b5). But this is all a little more advanced than the lesson he's presenting in that video.

[DesertTwang]

Thank you all so much for your responses! Really helpful.

JonPR, you actually answered another question that had me confused, and your explanation saved me from opening another thread about that:

I'm also taking online lessons with Bryan Sutton's Flatpicking School on artistworks, and in one recent exercise, Bryan has us crosspick through arpeggiated chords based on the G scale. It's very similar to what I was asking about in this thread, except that in his video lesson, Bryan calls the seventh chord "D7." This really confused me, because he goes through all the chords as I expected — G, Am, Bm, C, D, Em — but then suddenly, the last chord is yet another D chord before landing back on the G chord.

I chalked it up to him simply misspeaking and in fact referring to the F#m chord, but now I understand why he calls that a D7; as you pointed out, they're the same. The F#m chord consists of the notes F#-A-C, and the D7 chord of D-F#-A-C. I just never realized that because I didn't sit down and really compared the two until now.

The only thing that's still not clear to me is why the F# chord is called diminished. Wouldn't F#-A-C simply be F# minor?

Thanks again. I love this sub forum.

[Brent Hahn]

Originally Posted by DesertTwang

... Bryan calls the seventh chord "D7." This really confused me...

F#dim is the same thing, only without the D note.

[frankmcr]

Originally Posted by DesertTwang

The only thing that's still not clear to me is why the F# chord is called diminished. Wouldn't F#-A-C simply be F# minor?

No, F# minor is: F# A C# - only difference from F# major is the flatted third (A).

F# A C is a "diminished" chord because the third and the 5th are both flatted.

[mr. beaumont]

Originally Posted by DesertTwang

Thank you all so much for your responses! Really helpful.

JonPR, you actually answered another question that had me confused, and your explanation saved me from opening another thread about that:

I'm also taking online lessons with Bryan Sutton's Flatpicking School on artistworks, and in one recent exercise, Bryan has us crosspick through arpeggiated chords based on the G scale. It's very similar to what I was asking about in this thread, except that in his video lesson, Bryan calls the seventh chord "D7." This really confused me, because he goes through all the chords as I expected — G, Am, Bm, C, D, Em — but then suddenly, the last chord is yet another D chord before landing back on the G chord.

I chalked it up to him simply misspeaking and in fact referring to the F#m chord, but now I understand why he calls that a D7; apparently they're the same(?).

I think I get it now: The F#m chord consists of the notes F#-A-C, and the D7 chord of D-F#-A-C. I just never realized that because I didn't sit down and really compared the two until now.

Thanks again. I love this sub forum.

You might want to look into a teacher instead of random YouTube vids, they're crossing your signals.

Let me see if I can help. Let’s go back to that G major scale.

G A B C D E F#

Okay, so to make chords, we stack the interval of a “third.” Thirds are notes that are either 3 half steps or 4 half steps apart. There’s two different types of thirds, major and minor--Let’s just leave it at that for a minute, because all the notes we need to know are built right into that scale.

By taking every other note, we are finding those intervals of thirds. So…

G B D
A C E
B D F#
C E G
D F# A
E G B
F# A C

If we put names to these, we get the following chords

G major, A minor, B minor, C major, D major, E minor, and an F# diminished triad. That last guy doesn’t get used too often in most music.

I think you’ve got this part straight.

The 7th chord thing seems to be messing you up. That’s because of the crossover in language…there’s seven chords that can be found as belong to each scale, and one of them is the “seventh” chord (that’s our F# here)

But chords can also be harmonized further to include another note, and those 4 note chords are called “seventh chords.” To add insult to injury, there's not one type of seventh chord--but let's hold off on that for a minute. The one we are concerned with is the fifth chord of the scale, the "DOMINANT SEVENTH CHORD." Yeah, it's that important.

In the key of G—it’s the 5th chord, the Dmajor, is the DOMINANT--and that's the one that most often has the 7th added to it.

Take the “every other note thing” one step further: We get D F# A C.

This is a D7 chord. I think that gets a little confusing to people too, because the type of 7th interval in a “7th” chord is actually a “flat seventh.” Just accept that as it is for now, we can go further and things will make sense, but let me make sure this is as clear as can be first.

Making the 5th chord in a key a “7th” chord sounds great because the sound of it naturally pulls back to the “one” chord. Try it, play Dmajor to G major, then play D7 to G major. It’s a “satisfying sound” to the ears.

Let me know if this is helpful, and if you want to go on a bit more.

[Wissen]

Originally Posted by DesertTwang

Thank you all so much for your responses! Really helpful.

JonPR, you actually answered another question that had me confused, and your explanation saved me from opening another thread about that:

I'm also taking online lessons with Bryan Sutton's Flatpicking School on artistworks, and in one recent exercise, Bryan has us crosspick through arpeggiated chords based on the G scale. It's very similar to what I was asking about in this thread, except that in his video lesson, Bryan calls the seventh chord "D7." This really confused me, because he goes through all the chords as I expected — G, Am, Bm, C, D, Em — but then suddenly, the last chord is yet another D chord before landing back on the G chord.

I chalked it up to him simply misspeaking and in fact referring to the F#m chord, but now I understand why he calls that a D7; as you pointed out, they're the same. The F#m chord consists of the notes F#-A-C, and the D7 chord of D-F#-A-C. I just never realized that because I didn't sit down and really compared the two until now.

The only thing that's still not clear to me is why the F# chord is called diminished. Wouldn't F#-A-C simply be F# minor?

Thanks again. I love this sub forum.

Herein lies the difference between the academic understanding of Harmony and the real-world application of harmony.

The academic answer is: the chord built on the 7th scale degree of the G major scale is an F# half diminished. This answer is correct and necessary for the purposes of complete and total understanding. So there are no holes in the framework, as it were.

In the real-world application of this harmonic framework, the F#dim chord is almost never used. One explanation is that in Western Harmony we like our diatonic chords to contain the Perfect 5th interval (i.e. G and D in the I chord), and diminished chords are based on a Diminished 5th interval, or tritone.

This is the answer to your most recent question: Minor chords are defined a Major 3rd interval stacked on top of a Minor 3rd interval: an A minor chord is a major third: C-E, on top of a minor third: A-C. Reading the chord from the bottom up, as we normally do: A-C-E. This means the interval between the bottom note and the top note is a Perfect 5th: A-E

Diminished chords are a Minor 3rd stacked on top of a Minor 3rd: In an F#dim we have A-C stacked on top of F#-A. Reading the chord from the bottom up: F#-A-C. This means the interval between the bottom note and the top note is a Diminished 5th: F#-C. There is no such thing as a Minor 5th, which is a whole other topic.

So. F#-A-C is a diminished chord. F# minor would be voiced F#-A-C#.

As for what "half" diminished means, that is also a whole other topic.

Diminished chords can be used to great effect in all manner of music, but not usually in folk music and all of its descendant styles. Usually.

Therefore, as others have explained, the D7 chord is used as a substitute (aka functionally equivalent) because 1) It contains that P5th interval (D and A) to help the chord sound more "solid", 2) it contains that tritone (the same F# and C as in the F#dim) to create tension that begs to be resolved when the two notes in the tritone are 3) two leading tones that take a half step toward a note in the Tonic (I) chord (F# up to G and C down to B).

Now, to toss all of this back into the realm of semantics: say you play standard open chords in first position, and you fret a D7 chord in the universally accepted manner of wrapping your thumb around the neck to fret the F# on the low E string. Are you playing a D7 first inversion, or an F#dim? That depends on two factors: did your middle finger clip enough of the open middle D string to prevent it from ringing out (as this would be the only D note in that chord shape)? And what was your bass player playing (If he was on D, that's one thing. If he was getting fancy and walking, you could argue it was another)? Does it matter? To whom?

To bring all of that home, my conclusion: D7 and F#dim are functionally equivalent, so the vigor with which you defend the distinction depends entirely on what you are trying to prove.

[Wissen]

Originally Posted by mr. beaumont

The 7th chord thing seems to be messing you up.

I agree with most of your explanation, but I would offer one clarification:

A SevenTH chord is a chord that includes the 7th degree of the chord build on that note:

D7 = D-F#-A-C

I think the theory to explain all of that has been covered very well by the posts so far.

A Seven chord is the chord build on the seventh scale degree of the key in question:

In the key of G, F# is the seventh scale degree, so the chord built on top is the Seven chord. Seven chord is the general name: Diminished seven is the specific descriptor. F#dim is the seven chord in the key of G.

In parlance: Seven chord =/= Seventh chord.

This important distinction might be contributing to the confusion.

The reason for the -th is because we shorten the full name to a shorter name that retains all of the meaning: "A D Seventh chord" is just a shorter way to indicate that you should include the C, rather than just playing the basic D-F#-A triad. The C isn't always invited.

Cue the people who reverse these two terms in their mind: Music is a language. People use it in all sorts of ways to be able to communicate.

[mr. beaumont]

Originally Posted by Wissen

I agree with most of your explanation, but I would offer one clarification:

A SevenTH chord is a chord that includes the 7th degree of the chord build on that note:

D7 = D-F#-A-C

I think the theory to explain all of that has been covered very well by the posts so far.

A Seven chord is the chord build on the seventh scale degree of the key in question:

In the key of G, F# is the seventh scale degree, so the chord built on top is the Seven chord. Seven chord is the general name: Diminished seven is the specific descriptor. F#dim is the seven chord in the key of G.

In parlance: Seven chord =/= Seventh chord.

This important distinction might be contributing to the confusion.

The reason for the -th is because we shorten the full name to a shorter name that retains all of the meaning: "A D Seventh chord" is just a shorter way to indicate that you should include the C, rather than just playing the basic D-F#-A triad. The C isn't always invited.

Cue the people who reverse these two terms in their mind: Music is a language. People use it in all sorts of ways to be able to communicate.

I agree. It's also why I prefer Roman Numerals when referring to chords (but I don't know how to make that cool little circle with a line through it for half diminished)

[FwL]

Originally Posted by Wissen

Herein lies the difference between the academic understanding of Harmony and the real-world application of harmony.

[snip]

I was in a situation where I subbed on bass for the backup band at a local country music contest. One of the songs was in a major key and did, in fact, include the diminished vii chord with the bass line clearly outlining the triad.

The problem was that none of the other players could wrap their head around playing a Bdim in the key of C. When I pointed out that the bass line was laying out B diminished I was told by the lead guitar player that there is no such thing as a diminished chord in the major key and I was playing it wrong.

The rest of the band agreed with him, so we all played Bmin instead, and I tried not to visibly cringe, onstage, when the vocal melody rubbed against the chord.

.