Here's a picture of the four basic triads, major, minor, diminished and augmented. They can all be indicated in a variety of ways.
Major chords are usually denoted simply by the root note, e.g. a C major triad is simply named 'C'. Alternative notations are 'Cmaj' and 'CM'.
Other chords require something to qualify them from major chords. A C minor triad will be named 'Cm', 'Cmin' or 'C-'. A C diminished triad will be named Cdim, Co or C-. A C augmented triad will be named Caug, C+ or C+5.
Lilypond's defaults are to denote the major triad by its root alone, and the minor triad by adding a lower case 'm'. These conventions are now almost universal. The use of a minus sign for either 'minor' or 'diminished' has been so inconsistent that I think it best avoided altogether.
Lilypond names the diminished chord 'Co' and the augmented chord 'C+'; some people will prefer 'Cdim' and 'Caug'. There's an argument for preferring the part-words over the symbols - clarity. If you see 'Cdim', there's not question that a diminished chord is indicated. 'Co', on the other hand, is understood by some as indicating a diminished triad, others a diminished 7th.
The '+' sign is commonly used to indicate the augmented chord, but in Lilypond's chord syntax, the + is used to indicate a note (not necessarily the 5th) should be raised. I think this may cause confusion for users new to Lilypond. The use of '+5' to indicate an augmented triad only adds to the confusion.
On the other hand, the use of the 'o' and '+' helps to keep chord name compact, which is often desirable when there are several rapid chord changes in a piece and/or the performer needs to be able to quickly identify the chord he should be playing/improvising on.
Sevenths
Beyond the basic triads, the first extensions to consider are sevenths.
The "normal" 7th is the harmonic seventh (also known as the dominant seventh), which is a minor 3rd above the dominant (or 1 tone below the octave, if you prefer). This applies to both major and minor chords. The names Lilypond uses are shown on the first and third chords in the picture above.
The "major" 7th (also called the diatonic seventh) is a semitone higher than the "normal" 7th, and thus a major third above the dominant. (A major third is an interval of two tones, which is what "diatonic" means.) The diatonic seventh can also be added to both major and minor triads.
When added to a major triad, the name is variously written as Cmaj7, CMaj7, C with a triangle and 7, and C with just a triangle.
When added to a minor triad, the name is written as Cm(maj7), CmMaj7, CmM7, Cm+7 (a particularly confused notation), Cm with a triangle and 7, and Cm with just a triangle. (And I think I once even saw Cm(#7) in a magazine.)
The triangle is a very compact way of flagging the presence of the major 7th. It's also unambiguous, in that it clearly indicates the presence of the diatonic seventh. Its shortcoming is that it's not something that you can just type on a keyboard (which is important to some people), and there is the question about whether or not it can appear alone or should have a '7' appear after it.
The diminished seventh will appear as either Cdim7 or Co7 or C-7. I've already deprecated the use of the minus sign, so it comes back to the question of whether the part-word or the circle symbol is preferable.
Maybe there is a case for having two schemes - one whether the part-words are the preferred option, and a more terse scheme using the +, o and triangle symbols.
No comments:
Post a Comment