4

To build a 7th chord, my understanding is that you take the 1st, 3rd, 5th and 7th notes of the major scale.

So C7 would be

C D E F G A B

1 2 3 4 5 6 7

Applying this to Eb:

Eb F G Ab Bb C D Eb

1 2 3 4 5 6 7

Yet when I google the Eb chord it shows be that Eb7 has a Db rather than the D. What am I missing here?

  • Can you point to a source where C7 has a B instead of Bb? – piiperi Reinstate Monica Dec 1 '19 at 22:23
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    What came up when you googled a C7 chord? – Tim Dec 2 '19 at 15:57
  • The problem was that I built the C7 myself, thinking I was safe that I knew this chord. If I'd googled that first, I might have not been confused enough to post a question. Thanks for the answers! – CiaranWelsh Dec 2 '19 at 16:06
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    I vote to re-open this question because it is not a duplicate of the other question, as the latter implies already the knowledge of the dom7. The problem is the new question is too specific. It should be asked more generally Why does X7 have a a minor 7th and not a major 7? X7 might be replaced by any chord like .... Any user who has the same problem like OP wouldn't find the answers in the other question. – Albrecht Hügli Dec 3 '19 at 8:53
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There are several types of 7th chord. What you've constructed is the Major 7th, using the major 3rd and 7th intervals above the root. When abbreviated to a chord symbol, this is "Maj7" or "M7". There's also the Minor 7th chord, built using the minor 3rd and 7th and abbreviated "Min7" or "m7".

The one we abbreviate as just "7" is the Dominant 7th chord, built using the major 3rd and the minor 7th. That's because this is the naturally occurring 7th chord for the dominant chord (built on the 5th):

C D E F G A B C D E F

  • Also, the dominant chord tends to have the 7 in more classical progressions, whereas a 7th chord on the tonic was not as common IIRC. I.e. it is more common and useful to say V7 and not I7. – awe lotta Dec 4 '19 at 0:06
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"To build a 7th chord, my understanding is that you take the 1st, 3rd, 5th and 7th notes of the major scale."

That's true for major seventh chords. However, E♭7 is not a major seventh chord. If the chord symbol is just "7", the chord in question is a dominant seventh. One of the ways to construct this type of chord is to take the notes from the root's mixolydian scale, or if you don't understand modes, you could simply remember that it has a major third and a minor seventh. [E♭ G B♭ D] makes an E♭maj7 chord.

3

Following on Matt's answer.

There are several '7th' type chords, which need to be explained.

Major 7th - containing major 3rd and major 7th notes.

Minor 7th - containing minor 3rd and minor 7th notes.

Dominant 7th - containing major 3rd and minor 7th notes.

Diminished 7th - containing minor 3rd and diminished 7th notes.

Minor major 7th - containing minor 3rd and major 7th notes.

Major 7th is also called M7, or 'triangle' 7th. In key C, it's C E G B.

Minor 7th is also called m7, or -7. In key Cm, it's C E♭ G B♭.

Dominant 7th is simply known as 7 probably as it's the most used. In key C, it's C E G B♭.

Diminished 7th is also called o7, or 0. In key C, it's C E♭ G♭ B♭♭ .

Half diminished as another re-incarnation of a relative m6. (Also Co, but with line through circle). In key C, it's C E♭ G♭ B♭.

Minor major 7th is also called mM7. In key Cm it's C E♭ G B.

OP wasn't aware of the difference between '7th' and 'maj 7th' make up.

  • Thanks @Tim very useful indeed – CiaranWelsh Dec 2 '19 at 14:27
2

To build a 7th chord, my understanding is that you take the 1st, 3rd, 5th and 7th notes of the major scale.

A safer, broader understanding is: to build an xxxxx chord, you take the notes that are w, x, y and z semitones above the root of the chord. Given any name for xxxxx (major, diminished, sesqui-augmented pregnant nineteenth), the values of w,x,y,... are fixed. Count the semitones, and you can't go astray.

Of course in the heat of battle we use shortcuts. Most folks learn early on what a dominant seventh is, and then they consider a major seventh chord as a variation thereof.

  • The problem with counting semitones is that proper enharmonic spelling is thrown out the window. It's a good method to check your work, but used alone, strange results can arise: [G C♭ D E♯] doesn't represent a G7 chord very well! – user45266 Dec 4 '19 at 2:52
  • Professionals agree. newyorker.com/culture/culture-desk/… – Camille Goudeseune Dec 4 '19 at 4:55

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