This is the first in a series of articles on using Fretspace to explore music with a guitar or with another fretted instrument. Fretspace is a chord and scale editor for Mac computers. It is published by Softpress and is also available from the Mac App Store.

There are three types of chord that are fundamental to music harmony: major chords, minor chords, and dominant chords. D and Dmaj7 are major chords, Dm and Dm7 are minor chords, and D7 is a dominant chord. There are also other types of chords that are derived from these chords. You can use Fretspace to explore these types of chord and to see how they are related to each other.

Dominant seventh chords

Start by creating an empty chart and adding a standard D7 chord, which looks like this:

If you look at the Notes section of the Inspector panel, it should display the following information:

What this means is that you have a chord whose root is D, and whose other notes are a major third, fifth, and minor seventh from the root note. In fact “root, major third, fifth, minor seventh” (R 3 5 b7) is the chord formula for any dominant seventh chord.

Dominant seventh chords are often followed by chords whose root is a fifth lower. You probably know that the final chord in the key of G is usually G, and the previous chord is most often a D7 chord. Interestingly, dominant seventh chords are often preceded by minor seventh chords whose root is a fifth higher than the dominant chord; so the chord that precedes a D7 chord is often an Am7 chord. This is sometimes known as the ii-V-I progression: a minor chord on the second note of a scale (Am or Am7 in the key of G) is followed by a dominant chord on the fifth note of a scale (D or D7 in the key of G), followed by a chord on the root of the scale (G in this case).

Minor seventh chords

The formula for a minor seventh chord is similar to the formula for a dominant seventh chord, except that the major third is replaced by a minor third: R b3 5 b7 instead of R 3 5 b7. Take the D7 chord that you have and create a duplicate by selecting Duplicate from the Edit menu or by using the shortcut ⌘D. Now click on Major Third in the second popup of the Notes section and select Minor Third instead: this replaces the F# (major third) in the chord with an F natural (minor third) and you have a Dm7 chord:

Major seventh chords

You can create a major seventh chord in a similar fashion. The formula for a major seventh chord is the same as the formula for a dominant seventh chord, except that the minor seventh is replaced by a major seventh: R 3 5 7 instead of R 3 5 b7. Duplicate your original D7 chord and click on Minor Seventh in the Notes section, and select Major Seventh instead: this replaces the C (minor seventh) in the chord with a C# (major seventh) and you have a Dmaj7 chord:

Alternative shapes

If you have been playing guitar for a while, you probably know these shapes, but there are some other shapes that are less well known. Let’s take a standard C major chord, which looks like this:

If you have a song in which this is followed by a Cm chord, you might choose to play Cm with the following shape:

But there is an alternative, which is more closely related to the original C major chord. Add a standard C chord within Fretspace, and look at the Notes section of the Inspector panel. It should look like this:

We can convert this into an equivalent minor chord by replacing the major third with a minor third, but if you click on Major Third at this point you will find that the Minor Third option is disabled: Fretspace is unable to replace the second major third (E) with a minor third (Eb) because it is played on an open E string and we cannot lower it any further. There are two simple ways to get around this. We can remove this second E note from the chord (leave it unplayed) or we can replace it with a G note that is also in the chord. This gives us two alternative ways of playing C, both of which can be converted into Cm chords by using Fretspace to replace the major third with a minor third. Here are the major chords and their minor equivalents:

One reason to use these minor shapes in preference to the more common bar shape is because they create a smoother progression from the previous major shapes. Instead of jumping to a different set of notes, they progress by changing a single note, which is the note that differentiates them from the major chord.

Suspended chords

There are other types of chords that you can explore using the Notes Inspector. What happens if you replace the major or minor third of a chord with a suspended fourth or suspended second? Try doing that with a D chord and with other major (and dominant) chords. Press the Play button in Fretspace to hear what a chord sounds like, or play it on a real guitar.

Chord progressions in which the same chord is repeated over a number of bars sometimes alternate suspended chords with unsuspended chords, as a way of creating variety: A Asus A Asus and so on:

Minor-major seventh chords

Another thing you can try is to take a minor seventh chord and replace the minor seventh with a major seventh. What does that sound like? Try it with some common m7 chords, such as Am7 and Em7.One way to use these chords is to create chromatic (half-step) transitions between minor chords and minor seventh chords:

Add these chords in Fretspace and select them. Press Play to hear what they sound like, then press Play a second time while holding down the Option key, so you can hear what they sound like as arpeggios. You could also try reversing the progression (Am7 AmMaj7 Am) and see what that sounds like.

Diminished and augmented chords

So far, we’ve looked at what happens when we replace the third and seventh notes in a chord. What happens if we replace the fifth with a diminished (flattened) fifth or augmented (sharp) fifth? Try changing the fifth of a minor or major chord to a diminished fifth, or replace the fifth of a major chord with an augmented fifth. One way that you can use diminished and augmented chords is to create transitional chords. For example, Caug sounds good between C and F because the G# creates a chromatic (half-step) link between the notes G and A:

You can hear what this sounds like within Fretspace. Add a standard C chord to a chart, duplicate it and convert it to Caug (by replacing Fifth with Augmented Fifth) and follow it with a standard F chord. Select all three chords and press Play. You might also try using an Fmaj7 chord as the final chord:

Diminished seventh chords

Minor triads become diminished triads when you replace the fifth with a diminished fifth:

So what happens if we do this with a minor seventh chord, such as Dm7? Try it, and you will find that you get a chord that is known as a m7b5 (minor seventh with a flattened fifth). An alternative name for this chord is “half-diminished”. Why half-diminished? The reason is because it contains one diminished note, but there is a related chord which contains two diminished notes. Take a Dm7 chord and replace the fifth with a diminished fifth, then replace the seventh note with a diminished seventh note:

What we end up with is a diminished seventh chord, in which every interval happens to be a minor third. A diminished seventh note can be notated as bb7 to indicate that it is a minor seventh (b7) that has been flattened by an additional semitone, but it is actually the same note as a major sixth, and Fretspace notates it as 6 if you turn on Show Degrees. It’s easier to think of it in this way: most people prefer to say that the diminished seventh of C is A rather than Bbb.

Let’s look at a diminished seventh that is further up the fretboard. Take this Ddim7 chord and use Move Dots to move it two frets along the fretboard, so you have an Edim7. Now try moving the first note so that it is on the previous fret, and you will find that the diminished seventh becomes a normal dominant seventh with a root this is one semitone lower:

Now, an interesting feature of diminished seventh chords is that they are symmetrical (every interval is a minor third), which means that any of the four notes can be regarded as the root note. If you select the Edim7 chord and click on the Name popup in the Inspector panel, you will see that it could also be a Bbdim7 or a C#dim7 or a Gdim7. What this means is that you could lower any of the notes by one semitone, and you will end up with four different dominant seventh chords:

Because of this, diminished sevenths are a useful way of getting from one key to a different key. Here’s a progression that uses a diminished seventh to get from C7 to F#7:

What chord comes next is up to you, but since dominant sevenths commonly resolve to a chord that is a fifth lower, you could try adding a B chord of some description (major, minor, major seventh, dominant seventh, or minor seventh). Select the chords and press Play when you’ve done this, then press Play a second time while holding down the Option key. Then, if you like the sound, play it on a real guitar.

Altered chords

One other chord type that is worth knowing about is commonly referred to as an altered chord. This is a dominant seventh chord in which the fifth degree has been flattened or sharpened, or which has a ninth degree that is flattened or sharpened. Take a standard D7 chord and try flattening the fifth degree, or sharpening it, and see what it sounds like. You will probably think that it sounds discordant. That makes it a great chord. Music works by moving between dissonant and non-dissonant sounds. Dissonant sounds create tension that can then be released by moving to non-dissonant sounds. Dominant sevenths are dissonant chords: the seventh clashes with the root, and they also contain a tritone (6 semitone) interval between the third and seventh degrees. That’s why dominant sevenths are commonly used to create cadences (endings): you expect the dissonance to be resolved to a less dissonant chord. If you want to create a greater degree of tension than you would get from a normal dominant seventh, you can use an altered chord. It doesn’t matter too much whether you flatten or sharpen the fifth, or whether you add a flattened or sharpened ninth (or use chords that contain more than one altered note): the chords will sound different, but any of them can be used in place of a normal seventh chord. Here are some examples of altered E chords resolving to an A or Am chord:

Altered chords don’t have to resolve. You can also use them because you like the sound. Hendrix used 7#9 chords for their bluesy sound.