Building Seventh Chords

Here is a quick review of how to build the 5 most commonly used seventh chords.

The five most commonly used types of seventh chords are:

    1. Major seventh chord (M7, or MM7, a major triad with a major 7th)

    2. Dominant seventh chord (V7, or Mm7, a major triad with a minor 7th)

    3. Minor seventh chord (m7, or mm7, a minor triad with a minor 7th)

    4. Half-diminished seventh chord (dm7, a diminished triad with a minor 7th)

    5. (Fully) diminished seventh chord (o7, dd7, a diminished triad with a diminished 7th)

Here is a chart showing all five types built on the root C:

:8.18 seventh chords.jpg

If you know how to build intervals and triads, the above descriptions may be enough to help you construct the chords properly.  But here are a couple of important tips:


Try this fast and accurate method to build a 7th chord:


1. Stack up four notes on the staff in thirds (all notes are on lines, or all in spaces)

2. Make the 5th perfect, or not perfect as required by matching accidentals

3. Adjust the accidental on the 3rd of the chord if necessary, based on white key thirds

4. Use a 2nd to adjust the accidental on the 7th of the chord


This method is described in more detail below.  The techniques of matching fifths, using white key thirds as measuring devices, and seconds to measure sevenths are the things that make this method work so quickly and accurately.  These techniques will help you with many music theory and ear training notation problems besides building chords, so take the time to understand and learn them now. 


Here is a detailed step-by-step example of the above process:


Quick and accurate: This method, even though it takes a while to explain, goes very, very quickly when you use it, since it is very simple and visual.  It does not require a lot of counting of steps and half steps, or consulting a piano keyboard.  This is a technique that will help you read music quickly, analyze quickly, and make fewer mistakes.


Don't measure whole and half steps: Measuring out how many half and whole steps are in an interval is very slow, and not practical when trying to read, write, or analyze music quickly.  Counting out many half or whole steps is also more prone to error than the two-step methods used here.  All intervals can be created by counting no more than two whole steps. Fifths and sevenths are faster and easier to spell than thirds!  Fifths can be analyzed at sight without any measuring, and sevenths can be analyzed by measuring only one whole or half step.


Don't stack up thirds: If you memorize 7th chords as stacks of major and minor thirds, this is slow (you have to count out all the whole/half steps in every third) and also quite prone to error.  If you accidentally make an error on the third of the chord, all the other notes will be wrong.  In my method, each note relates to the root and is independent of the others, (which is true musically/acoustically and the way your ear will hear the notes) so that if you make any errors at all, only one note will be affected.


You can use exactly this procedure to construct any seventh chord you need.  For a demonstration of this process, let’s build a M7 chord.


1. Stack up four notes on the staff in thirds, for the moment, do not use any kind of B for the root of the chord.  Feel free to put a sharp or flat on your starting note.  I will choose F# for my example. 


2. Match up the fifth of the chord next. (This is the easiest note to find without counting any steps.)  Rather than building a stack of thirds one on top of the other, we will measure all chord intervals from the root, since this is faster and more accurate. We don’t need the third there to find the fifth.  Since we need a P5 in this type of seventh chord, all we need to do is “match up” the accidental on the fifth of the chord to be the same as the one on the root. If there is no accidental on the root, then you don’t need one on the fifth for it to be perfect (except for the fifth B-F, which is a d5).  In my example, since I have a sharp on the root F#, I am going to also put a sharp on the fifth of the chord, C#.  If you are wondering how it could be that easy, follow the link to the magic of perfect fifths page.


3. Next, make the third of the chord into a major third.  Again, in order to do this, I am not going to count out the steps exactly.  I use a faster system based on the fact that I can easily tell how far apart the notes of any third are without using the piano, then I adjust for the accidentals as necessary. Only the letters E & F, and B & C are half steps.  The rest are whole steps. 


To measure the distance between D and F, for example, I just name the three letters D-E-F.  When saying this, I can tell that one of them, E & F, is a half step and the other is a whole step, making this a m3.  If the notes are G-flat and B-flat, I can use the same technique: G-A-B, those are whole steps.  G & B are a M3 apart, and therefore G-flat and B-flat are also a M3, since both notes are flatted the distance between them will still be the same.


The “white key” notes in the third F and A (don’t worry about the # yet) are always two whole steps apart (just say the letters F, G, A: F-G is a whole step, and G-A is a whole step.)  Therefore, F and A are always a M3 apart.  If we want to build a M3 on F#, we will also have to sharp the A for the space between them to stay the same.  In other words, if F-A is a major third, then F#-A# is also a major third  (also F-flat to A-flat, and F double sharp to A double sharp are M3's – you get the idea).  If you know your white key notes, which is very easy, since they are all whole steps except B-C and E-F which are half steps, you can measure out any third quickly this way in your head without needing to go to the piano.  This process works no matter what sort of difficult accidentals the third has, or whether it is ascending or descending. So, in the case of building our M7 chord, we need the A to have a sharp on it so that it will be a M3 above the F# root.


4. Use a 2nd to construct the seventh.  As you might have guessed, my method does not involve counting up all the whole and half steps from the bottom to the top note.  There is a much easier way, and you should use this when you build any seventh interval, not just when making a chord. 


In this method, we will just look at the two notes of the seventh as if they were a 2nd, right next to each other on the piano (again, know your white key notes!)  In this case, my root is F#, and the top note in my stack is E.  Do I need to sharp it or not to make this a M7 chord?  In order to decide we need to know how big each type of seventh interval is. 


Instead of thinking that a M7 interval is 5 ½ steps and that a m7 is 5 steps, it is much simpler to measure them by saying a M7 is one half step smaller than an octave, and a m7 is a whole step smaller than an octave.  If we leaped up an octave from our root note F#, how far is the seventh interval note E below that F#?  You will see that it is a whole step below F# (or if you know your white keys you don’t even need to look at a keyboard - since E and F are always a half step, E and F# will be a whole step). So, as the note stands now without any accidental on it, E is only a minor seventh above F#, since it is a whole step below the F# octave note. 


To make this into a M7, we need the E to be a half step higher, a half step below F#, which is the note E#.  Be careful if you are using the keyboard, since it is easy to fall into the trap of calling this note F instead. 


On the keyboard it certainly looks like we should call it F, but in fact, we must call this note by the letter name E, not F, in order that the letters in this chord can stack up properly in thirds.  This is the reason I asked you to draw in your notes on the staff back in step one.  If you’ve got them arranged properly in thirds, you will know this note needs to be some kind of E.  Never erase notes in your stack to respell them as another letter name, as this will not create a proper chord.  E# may seem like an odd note, but it is the correct way to spell this M7th chord.


That is all you need to do: stack the notes, match the fifth, adjust the accidental on the third, then build the seventh.  Master this method, using the matching technique for fifths, measuring thirds by knowing the distance between those letters without accidentals on the white keys, and measuring sevenths by using seconds, and you will find that your speed and accuracy improves greatly.




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