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If this diagram is accurate, would the 7th of a Bmin7 be formed from a minor 7th interval or a major 7th interval, e. g. A-natural or A-sharp? I'm assuming A-natural. If this line of thinking is wrong, what is the proper way to denote the 7th interval and also, while at it, how to determine the 9th?

Update:

I've narrowed down my confusion: the composition of a triad chord is the 1st, 3rd, and 5th interval from the root. However, some cases notes in this triad are a sharp or flat note. Is there any system or rule set that can be universally followed to determine those cases? or is it just by memory?

Another Update

Ok so I've narrowed down (based on answers below) that whether a note is a sharp or flat is determined on the key. So I guess the answer to my question is how to determine a key of a note through some sort of rule set, as in do this, this, and this to determine the key of C. If this doesn't exisit, I will result to memorization I assume.

Also have determined so far that the diagram below is wrong because occasionally a chord will start with a sharp and have sharps as the 3rd interval, so that isn't represented below.

Another Update

So based on feedback below, to know whether notes in a chord are sharp are flat is basically knowing the scale. The pattern I was seeking was TTSTTTS, thanks tim. It is Tone & Semi Tones. I will have to do some more research but thank you everyone for contributing. Please feel free to add more thoughts below.


enter image description here

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This chart seems to me to be unhelpful, as in 7th notes,or will other relevant notes shine blue for other chords?It appears to show that note A is the same A in maj. and min. It isn't. –  Tim Sep 10 '13 at 17:10
    
The way this chart currently stands, the acceptable 7th would be a major or minor A and either of those two notes would be blue. I think I'm learning that this method is inaccurate –  Brian Sep 10 '13 at 17:14
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Use the A for both min.7th and dom.7th, and the A# for maj.7th. This will put all 3 chords right.There seems to me to be a lot of mis-information out there in the big wide web. –  Tim Sep 10 '13 at 17:18
    
@Tim - agreed, I just posted an answer that will hopefully add some good information to the web. –  jjmusicnotes Sep 10 '13 at 17:49
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The sharps and flat bits are purely down to whether the appropriate notes in the triad or tetrachord are sharp or flat in the key to which they are . –  Tim Sep 10 '13 at 20:15

4 Answers 4

up vote 4 down vote accepted

You've maybe been confused by the fact that Bmin. scale sometimes has A# in it. The Bmin. harmonic always does, whereas the Bmin. natural never does, and the Bmin. melodic sometimes does !! Confusing. Yes, very. However, the standard Bm7 , as Wheat states, is B-D-F#-A, using the minor seventh interval of B to A. There is another chord which does use A#, and it's called Bminor major 7, sounding not too stable and often used as a bridging chord .

To understand this lot more easily, use Cmaj. as a starting point. Count TTSTTTS as you go through the scale. It gives CDEFGABC. This will translate , starting at D, for example, as DEF#GABC#D.All maj. scales work in this way, and you need to keep 'black' notes as either # OR b. Don't mix them ! Working on to minors, use the major as a template, but for example, on natural min., flat the 3rd, 6th and 7th notes. If they happen to be #, then they'll become naturals. If they're naturals, they become flats.This is a fair simplification,but I hope it's enough to get you well on the way.

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Thanks, is there any pattern or method to determining when a note is sharp or flat within a chord? Im not exactly clear as to when F# became F# rather than just F. And with F# being in the chord, that makes this chart incorrect? It was supposed to display when Maj, min, Aug, Dim, and perfect notes are acceptable. –  Brian Sep 10 '13 at 17:09
    
@BrianAnthonyDillingham - yes, please see my answer. –  jjmusicnotes Sep 10 '13 at 17:21

The pitches in a Bmin7 chord are B D F# A. "A-natural" is the seventh scale degree of the B minor scale, and forms a minor 7th interval from the tonic note of B natural.

enter image description here

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Thanks, is there any pattern or method to determining when a note is sharp or flat within a chord? Im not exactly clear as to when F# became F# rather than just F. And with F# being in the chord, that makes this chart incorrect? It was supposed to display when Maj, min, Aug, Dim, and perfect notes are acceptable. –  Brian Sep 10 '13 at 17:11

There are four parts to reading macro-analytical chord nomenclature, which I will break down below. First, let's take the chord from the question:

Bm7


B

^

The first part of the chord "B" will tell you what pitch-class the triad is based off of. In this case, it's B. If you saw the chord "Am7", the first part of the chord would indicate some type of "A" chord.


m

^

The second part of the chord "m" will indicate the quality of the chord. A lower-case "m" is used for minor, an upper-case "M" for major (when not dealing with 7th chords,) and "dim" or "aug" used for diminished or augmented chords respectively. Now, there is alternative notation such as a "-" used to signify minor and a "+" to signify augmented.

Alternatively, you may see "°" for diminished chords and a line through the same circle for half-diminished chords.


7

^

The last part of the chord denotes either how the seventh will be treated and / or how any extensions will be treated if used. The "quality" component of the chord and this last component are a little intertwined as a half-dim symbol would obviously apply to the seventh and not the triad. In a seventh chord the 7th is always flatted when presented by itself:

D7 = D, F#, A, C B7 = B, D#, F#, A Ebm7 = Eb, Gb, Bb, Db

etc.

The seventh is only different when specifically notated to be so:

BM7 = B, D#, F#, A# CmM7 = C, Eb, G, B F#°7 = F#, A, C, Eb

This portion of the chord is also where any special alternations to the original triad might be located, for example, a commonly different spelling for a half-diminished chord is "m7b5" such that:

Am7b5 = A, C, Eb, G


The last part of the chord is where compound intervals are located. These are also know as upper-tertian extensions. Here you'll see 9ths, 11ths, and 13ths added or altered in chords:

Bm7(9) = B, D, F#, A, C# Bm7(b9) = B, D, F#, A, C Bm7add11 = B, D, F#, A, E Bm7add13 = B, D, F#, A, G#

If all notes up to a compound interval are expected to sound, then the 7th is dropped and the extension takes the place:

Bm9 = B, D, F#, A, C# B13 = B, D#, F#, A, C#, E, G#

As you can see, in both cases the 7th is still flatted. This is due to historical and contemporary performance practice. The rule still applies. If the 7th is to be altered, it must be notated as such:

BM7(13) = B, D#, F#, A#, C#, E, G#

Upper-tertian extensions may be altered in any way:

Bm7(#9)(addb13) = B, D, F#, A, C##, G

As you can see, because I "added" the 13, the 11th was omitted.


Obviously, there is more nomenclature, notation, and other shorthand elements, but above are outlined the basic premise and process of reading chord nomenclature.

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This is great and informative! thank you for explaining. Can you touch on when or why a note becomes a sharp or flat though? Im looking for some sort of explanation or system that determines that. –  Brian Sep 10 '13 at 19:56
    
I can determine which notes to use in a chord, but when it is sharp or flat or natural eludes me. Thank you for your thorough explanations! –  Brian Sep 10 '13 at 19:57
    
Think of the chords in terms of intervals, i.e. # of semitones, from the root. Depending on your root, sometimes those intervals will fall on a note representable without sharp/flat, and sometimes you need a sharp/flat. As an example, any chord with root C will have all of its notes a semitone higher than a chord with root B, so for many of them, you need sharps/flats in one root or the other. –  microtherion Sep 10 '13 at 20:54
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@BrianAnthonyDillingham - I suggest you take a look at the circle of fifths, funny things called tetrachords, and how major scales are built. –  jjmusicnotes Sep 11 '13 at 0:49

I would advise you not to learn the types of chords like this. You need to understand what it means for a chord to be minor / Major and what it means to be Augmented / Diminished. If you only have notes that are in the scale of the Key then sure there are patterns that arise but no composer is forced to only play notes that are comprised of in the scale.

There are a plethora of reasons why a composer would like to use chords that do not form part of the scale. If you do not know what it means for a chord to have this characteristic then somehow you are now unable to discern what type of chord you are seeing. Which is bad.

To teach theory in this way. To simply make it a memory exercise to me is to teach it in non intellectually engaging manner which will not lead to theory success.

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