Chord construction on guitar

Question

I know that a major chord is built using the root, a third, and a fifth and that the root note is always the note with the lowest frequency.

So in a guitar, a C major chord would have the notes C(3rd fret on the A string), E(2nd fret on the D string) and an open G string.

My question is why do we play the higher octave C (1st fret on B string) and open E string?

As the C major chord is a triad, shouldn't we be playing only 3 notes at a time and mute the B and high E string like how we mute the low E string? If I include the higher octave C and E, wouldn't it change things? Because clearly just plucking the 3 strings to play C E G and strumming all the 5 strings have two different sounds.

And even if we do play 2 different notes that are an octave apart in the same chord, would the chord be renamed as and add8 or add10?

Answer 1

As others have stated, C major contains notes named C, E and G. They can be played in any order, there can be one of each, or a dozen of each in different octaves, and it's still C major. You could play on piano, 7 gs, 2 Cs and an E, and it's still C major!

Voicing is the buzzword here. By using different Cs, Es and Gs, different effects are created. Nothing will change the C-ness of that set of notes, but there are hundreds of different combinations of the three. Close voice combinations are most often the case on guitar, but with piano, there could be an open voice chord with a low G, middle C and high E. Yes, still C major...

On guitar, using an open C chord, several versions (voicings) are readily available. Using all 6 strings. Although the one usually found is X32010, there are:032010, 332010, 032013, 332013. Some work better than others in certain places, but it's nice to have different options under your fingers. None of them is any 'righter' or 'wronger' than the others.

Answer 2

I know that a major chord is built using the root, a third, and a fifth...

You should be specific with the interval qualities in this case, because you wrote major chord. Minor and diminished triads also have thirds and fifths, but the are respectively minor thirds and diminished fifths. A major triad is a root, a major third, and a perfect fifth.

...the root note is always the note with the lowest frequency.

No. The root is always the root. The lowest frequency tone is called the bass. The bass is not necessarily the chord root. The concept you need to review for this is chord inversion. The quick explanation is arrange the letters of the chord alphabetically in thirds, the first letter is then the root tone. Ex. E G C the bass is E but the order in thirds is C E G the first tone C is the root.

As the C major chord is a triad, shouldn't we be playing only 3 notes at a time...

The critical concept here is pitch class. Pitch class being the lettered tones regardless of which octave they are in. Strictly speaking a triad isn't 3 tones, rather it is three pitch classes each being a third apart.

...shouldn't we be playing only 3 notes at a time and mute the B and high E string...

Those two extra tones - the C and E one octave above are just part of the pitch classes C and E so in terms of triads they are just duplicates and the chord is comprised of only 3 pitch classes.

Answer 3

Actually the name of the chord refers to the different notes it contains. So, as you correctly said, the C major triad contains the notes C E G, if you play another C E G one octave higher, it's still a C major triad, because you are just repeating the same notes.

In you example in a guitar, of course you can play only those 3 strings if you want, and it does sound different if you add the higher C and E, and that's entirely up to you. You can even play C major chord in different shapes, for example X35553 (C G C E G). It's still C major. The chord would be renamed if you add a different note, for example B, which would make a Cmaj7.

As for why do we play the higher C and E (in general), I think it's just because it sounds better to most people. By adding those higher notes it sounds more complete and bright to our years than just C E G, don't you think?

Answer 4

The name of a chord comes from the different notes involved and its structural quality. That is why we have major, minor, diminished, and augmented chords. A C major triad will always only have C,E, and G as the notes. The notes can be doubled (or more in larger ensembles), but this does not change its major quality. The chord can be placed in different inversions, with a note other than C in the bass, but again this does not change its major quality. The doubling of notes and use of inversions can be used to describe how the chord is being used, but that does not require a different name for the chord.

Answer 5

A triad has 3 notes, But can have many pitches. To help you understand what I mean, a note, let's say a note named C, can be played in many octaves, but it is still a C. The only requirement for a C major triad is that it contains C, E and G. at least 1 of each. It doesn't really matter what order they are in, what octave they are played in, or it they are repeated.

As you learn more you will learn that there is something called inversions, which tells you what the lowest note is.