Chord Construction Fundamentals         How chords are constructed A chord is a group of tones sounded simultaneously. The numbers and symbols used to identify intervals are also used to symbolize the individual tones of any chord — chord tones are intervals. Your knowledge of intervals then, their names, numbers, and symbols, will have immediate application to chord construction. [This is why I’ve included a large intervals primer on this web site.] But how do you know which tones (which intervals) to combine when building chords — good ears aside? In formal composition, scales (with their predetermined sets of intervals) are used as guidelines for selecting chord tones. Elementary chord construction starts by using only those intervals contained in particular (fixed) seven-tone scales. e.g. only the intervals of the Major scale, or only the intervals of some minor scale. Such scales (such restricted sets of intervals serving as composition guidelines) are called keys. Within that broader guideline, there are two more criterion to observe when selecting chord-tones. In simple language, chords are constructed in the ascending direction (i.e. from the lowest tone up), and using (only) every other (ascending) scale tone above the given root — commonly called third intervals, or simply thirds. So chords are constructed by taking any seven tone scale and applying a technique called chord construction in thirds to/from any or all of its scale degrees. To understand chord construction then, we must first understand what thirds are. A third is a type of interval — as are fourths and fifths, etc. Recall from our discussion of intervals that the number-names (values) of all intervals are derived from the scale-degree position numbers used to mark the tones of any seven-tone scale. The tonic of any scale is numbered the “one” tone or the “first”. The next higher pitched tones are numbered, in ascending order, the second, third, fourth, fifth, etc. Those same position numbers are then used as interval number-names. For example, the interval (the distance) from the first tone of the scale to the fifth scale tone above it, is called a fifth interval. Fifth intervals, then, are found by counting tones present and available within the key until you reach the fifth tone above the given tonic or root. The thing to understand here is that this principal “counting tones present and available within the key” is used universally in music theory to locate and name intervals no matter which tone of the scale you take as number one. In chord construction, every tone of every scale will eventually be used as a one tone, i.e. the root of a chord. So from any tone in the scale/key; by counting scale tones (to the right) ... 1 ... 2 ... you’ll find a second interval, ... 1 ... 2 ... 3 ... a third interval, ... 1 ... 2 ... 3 ... 4 ... a fourth interval, and so on. So successive third intervals (the building blocks of chord construction) are found by counting (to the right) ... 1 ... 2 ... 3, ... 1 ... 2 ... 3, ... 1 ... 2 ... 3 — overlapping the 1’s on top of the 3’s. That is, each pervious 3 becomes the new 1, the new tonic/root — the starting-point of the next interval calculation. Figure 1a and 1b illustrate how to find successive third intervals, in the key of C Major, from tones C and D.     Figure 1a       Figure 1b       Knowing how to locate successive third intervals is the first step in understanding chord construction in thirds. The next step is to understand the connection between successive thirds and additive thirds (and to understand the connections in the numbers used to depict them) — where, for example, two successive third intervals equal a fifth interval, and three thirds equal a seventh etc. This connection is illustrated next. Figure 2 shows that the interval from C to G can be measured as being either two thirds or one fifth.     Figure 2       Finally, by combining the ideas (and numbering means) of successive thirds and additive thirds, standard chord-formula like R, 3, 5 and R, 3, 5, 7 begin to make sense (see Figure 3). The first tone of the chord is the root (marked R). The next tone (the 3rd of the chord) is a third above the root. The next tone (the 5th of the chord) is a third above the 3rd (it’s also the fifth available scale tone above the current 1 tone). The last tone (the 7th of the chord) is a third above the 5th, etc.     Figure 3       This process of constructing chords in thirds can be continued further, adding the 9th, 11th, and 13th scale tones (above the given root), to create ninth chords, eleventh chords, and thirteenth chords. Remember, you can (and will) apply this technique to/from all seven tones of any given scale or key. So using third intervals (alone) you can construct the following chord-forms above each degree of any seven-tone scale:     Figure 4       Elementary chord construction, then, is very mechanical in nature, and the resulting chords seem to be almost random creations (i.e. you take what you get). While the process is mechanically simple, identifying the chords so created is not. Figure 3, for example, shows three seventh-chords constructed (in generic or stock thirds) above three different degrees of the C Major scale, i.e. on tones C, D, and G. But what kinds of seventh chords are they? The member tones of these three chords are in fact only partially and incompletely symbolized. Those chords were constructed in stock thirds, as they should be, but we still don’t know what kinds of thirds (Major or minor) we combined (or wound up with) every time we added a third to any of our chords. And standard procedure doesn’t make it easy for us to find out. While it is possible to do, there is no simple way to identify the exact widths of intervals by looking at their (seven thing oriented) letter spellings. Such things are usually learned by memory instead. i.e. you’d know (from memory) the intervalic make-up and formula of all common triads and seventh chords, and you’d have memorized (at least) the types of triads and seventh chords that occur naturally above each degree of any Major scale. In other words, you’d know that the naturally occurring seventh chord above the second scale-degree of any Major scale (the supertonic degree) is a minor-seventh chord, and you’d also know that all minor-seventh chords are composed of a minor triad plus a minor-third interval. So in the end, you’d side-step specific letter spellings whenever possible and focus instead on what you know should occur (when and where) and extrapolate any differences from there. For now then, I’ll simply tell you the kinds of seventh-chords we created above tones C, D, and G (of the C Major scale), and I’ll show you the correct and complete way to render their (standard) number-formula — inserting accidental marks (in this case flats only) as needed. I’ve also added the Cipher formula (half-step value numbers) so you really know what’s there. Even at their best, standard musical number formula are less than revealing. [Note, the Master Charts catalogue all number-formula (standard and Cipher) of all naturally occurring chords (triads through thirteenths) above all scale degrees of the Major and three minor scales.]     Figure 5           On to chord progressions on the guitar.     Up to Top of page