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Diminished 7th Chords. Do you respell them? Violin, or other instrum

violin diminished 7th chords respell enharmonic

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#1 BadStrad

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Posted 20 August 2016 - 17:26

I was flicking through the theory and violin practical leaflets and I got to thinking about diminished seventh chords.  I know!  It's all go in my house.  :)

 

Starting from the major scale the  "recipe" is (1)  ¨3  ¨5   ¨¨7  or by interval (1) m3 dim5 dim7.

 

So starting on G you'd have G Bb Db Fb.  So far so good.  But, I've heard that some people teach the chords using enharmonic names, which I didn't really get, because (using the example here):

 

(a) If you use the E, then you're using the sixth of the scale, not the seventh, so it's not a seventh chord any more. 

(b) I was always taught that you shouldn't mix sharps and flats in a chord.

© From a strings point of view.  If you are playing in a quartet then the intonation is different for a Db than for a C#.  OK at grade five a player might not have the skill to recognise the finer points of the intonation difference, but down the line couldn't this become a problem?

 

So I was wondering what teachers here on the forum do.

Would you teach the chord as those notes or use enharmonics  such as G Bb C# E?

 

Theory wise these don't come up until grade seven, but they are in grade five practical, so do people:

(a) go through the theory of how to create the chord and then either use the basic recipe (so in this example the one with all flats) or

(b) create the chord and then use the enharmonics (a mix of sharps and flats in this example) or

© just give the chord.

 

If ©, which version do you teach?

 

Obviously I'm coming at this from a violin perspective, but I'm equally interested in how teachers of other instruments approach this.


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#2 sbhoa

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  • Tameside

Posted 20 August 2016 - 18:17

I go with the recipe as being a stack of minor 3rds. For this to work properly enharmonics don't really work but as there are only really three different combinations of notes if you go with all the rest as inversions it doesn't always come out so neatly. I've only taught them on piano where it's easier to do as a visual thing.


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#3 Latin pianist

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  • Cotswolds

Posted 20 August 2016 - 18:37

I do adopt a different attitude between learning the construction of scales, arpeggios etc, and the learning to play them. Eg when teaching the 3 black note majors, I explain that you play all the black notes with B and E or C and F for B and Db majors, but for F# major, we remember B and F. But I do make sure they know it's really E #.
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#4 Hildegard

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Posted 21 August 2016 - 04:46

I was flicking through the theory and violin practical leaflets and I got to thinking about diminished seventh chords.  I know!  It's all go in my house.  :)

 

Starting from the major scale the  "recipe" is (1)  ¨3  ¨5   ¨¨7  or by interval (1) m3 dim5 dim7.

 

So starting on G you'd have G Bb Db Fb.  So far so good.  But, I've heard that some people teach the chords using enharmonic names, which I didn't really get, because (using the example here):

 

(a) If you use the E, then you're using the sixth of the scale, not the seventh, so it's not a seventh chord any more. 

(b) I was always taught that you shouldn't mix sharps and flats in a chord.

 

The diminished 7th in question is simply an inversion of chord VII7 in the key of D minor:
C# - E- G - Bb

 

I don't know where the idea of not mixing sharps and flats in the same chord came from, but it is incorrect. Sharps and flats occur together in keys such as G minor and D minor, so it is inevitable that sharps and flats will occur within the same chord in these keys.
I always teach dim 7ths as being seventh chords on the leading note of a minor key:

Chord VII7 in A minor: G# - B - D - F 
Chord VII7 in D minor:  C# - E - G - Bb
Chord VII7 in E minor: D# - F# - A - C

 

As sbhoa says, there are actually only these 3 diminished 7ths. All others are inversions of one of these, sometimes with enharmonic spellings, although I prefer to keep to stacked minor 3rds for simplicity.


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#5 BadStrad

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Posted 21 August 2016 - 10:52

I don't know where the idea of not mixing sharps and flats in the same chord came from, but it is incorrect.

That would be one of only two things that registered from school music lessons (the other was sonata form). We got told it so often, but of course when it comes to minor keys it falls apart. Maybe looking back they were talking key signatures. That makes more sense. My brain must have been as foggy as the weather's been recently. :)


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#6 SingingPython

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Posted 21 August 2016 - 10:55

Having learnt them first on piano and then on violin and never formally within theory, I'm inclined to ignore the issue of "how" to write them as much as possible.  Understand them as minor thirds, learn them visually on the piano; on violin you need to understand that two minor thirds don't quite reach a 5th so therefore crossing strings you will always be moving fingers back until finally you can slip in an open string or need to shift everything up again.


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#7 BadStrad

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Posted 21 August 2016 - 11:41

As I said, the brain was foggy yesterday, so maybe I should have thought a bit more before posting.  I was definitely not thinking about minor scales (as was obvious from comments above) because the recipe I think of for creating a dim7 chord is based on a major scale.

 

I get that there are only three note combinations that make up diminished seventh chords, with the rest being inversions, but it struck me that if you don't use the correct enharmonics then you haven't got a dim7 chord in terms of how one would be created from a scale.  Perhaps I can clarify what I'm musing about.

 

So a diminished seventh starting on G would be  G Bb Db Fb  ie using the note *names* of the first, third, fifth and seventh of the chord.  If asked to write that chord in a theory exam those would be the notes.

 

Respelling the chord as G Bb C# E is using the note names of the first, third, fourth and sixth, which is a different "chord recipe," so if a candidate wrote that as a dim7 starting on G surely it would be wrong?

 

Of course, not many pupils take grade seven theory, so I suppose from that point of view it doesn't matter on an equal temperament instrument what note names you use, but outside of equal temperament Bb to C# and Bb to Db are two different animals, which is why the idea of using G Bb C# E for G Bb Db Fb struck me as odd.  Maybe that's what I'm grasping at - the idea of the notes as just being inversions of three chords (so kind of a stand alone "thing") and of the chords appearing in some kind of context (ie how they relate to the music they're a part of).  So I think what I'm getting at, is that while it might be easier to learn three chords and just invert them,  if you don't use the correct enharmonics, then the chord isn't functioning as a dim7 of whatever key the music is in.

 

@SingingPython, I think you were addressing my question about violin intonation ("on violin you need to understand that two minor thirds don't quite reach a 5th so therefore crossing strings you will always be moving fingers back until finally you can slip in an open string or need to shift everything up again.") but I'm sorry didn't really get what you were saying here.


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#8 Hildegard

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Posted 21 August 2016 - 16:11

Maybe that's what I'm grasping at - the idea of the notes as just being inversions of three chords (so kind of a stand alone "thing") and of the chords appearing in some kind of context (ie how they relate to the music they're a part of).  So I think what I'm getting at, is that while it might be easier to learn three chords and just invert them,  if you don't use the correct enharmonics, then the chord isn't functioning as a dim7 of whatever key the music is in.

 

 

 

That is true, but in AB Theory exams you are not asked to write diminished 7ths - you may have to identify one in a musical extract, but in the harmony questions you are told which notes to use by means of figured bass or (in Grade 7, Question 2) by following the given harmonic skeleton.

 

When a dim.7 has a harmonic function it is often spelled to reflect that function, so your example of G-Bb-Db-Fb would use those letter names if it was chord VII7 of Ab minor. But exactly the same pitches would be written as G-Bb-C#-E if functioning as VII7 of D minor or as E-G-Bb-Db if functioning as VII7 of F minor (*). There is no rule that this has to be done, though - it's just a matter of what is more logical in the context. It is also important to remember that a dim.7 is often used purely for chromatic colour - not as a functional chord. So E would be preferred to Fb in sharp keys, or in C major, for instance.

 

The dim.7 effectively functions like a dominant chord (some people like to think of it as a dominant minor 9th with the root omitted). The symmetrical nature of the dim.7 means that aurally there are only three such chords, together including all 12 pitches of the chromatic scale. Each dim. 7 can function as a quasi-dominant in any of eight keys (four major and four minor). This unique property makes the chord invaluable for modulations to remote keys (albeit sometimes rather abrupt modulations).


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#9 BadStrad

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Posted 21 August 2016 - 17:13

 

When a dim.7 has a harmonic function it is often spelled to reflect that function, so your example of G-Bb-Db-Fb would use those letter names if it was chord VII7 of Ab minor. But exactly the same pitches would be written as G-Bb-C#-E if functioning as VII7 of D minor or as E-G-Bb-Db if functioning as VII7 of F minor (*). There is no rule that this has to be done, though - it's just a matter of what is more logical in the context. It is also important to remember that a dim.7 is often used purely for chromatic colour - not as a functional chord. So E would be preferred to Fb in sharp keys, or in C major, for instance.

 

 

I think that's what I've been trying to get to - what's logical in context?  If the chord isn't constructed of the note names of the first, third, fifth and seventh, of the key signature, but using the first, third, fourth and sixth names (as mentioned above), doesn't that make sight reading the chord much harder? 

 

Thinking about modulations, I would assume that logically the best spelling would be one that respects the leading note.  So in Dm you'd want to use C# rather than Db and so on.


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#10 sbhoa

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  • Tameside

Posted 21 August 2016 - 17:48

 

 

When a dim.7 has a harmonic function it is often spelled to reflect that function, so your example of G-Bb-Db-Fb would use those letter names if it was chord VII7 of Ab minor. But exactly the same pitches would be written as G-Bb-C#-E if functioning as VII7 of D minor or as E-G-Bb-Db if functioning as VII7 of F minor (*). There is no rule that this has to be done, though - it's just a matter of what is more logical in the context. It is also important to remember that a dim.7 is often used purely for chromatic colour - not as a functional chord. So E would be preferred to Fb in sharp keys, or in C major, for instance.

 

 

I think that's what I've been trying to get to - what's logical in context?  If the chord isn't constructed of the note names of the first, third, fifth and seventh, of the key signature, but using the first, third, fourth and sixth names (as mentioned above), doesn't that make sight reading the chord much harder? 

 

Thinking about modulations, I would assume that logically the best spelling would be one that respects the leading note.  So in Dm you'd want to use C# rather than Db and so on.

 

It can take me longer to work out what it is though the mixture of accidentals can be a clue.


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#11 Hildegard

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Posted 22 August 2016 - 07:06

 


I think that's what I've been trying to get to - what's logical in context?  If the chord isn't constructed of the note names of the first, third, fifth and seventh, of the key signature, but using the first, third, fourth and sixth names (as mentioned above), doesn't that make sight reading the chord much harder? 

 

The immediate context is the chord that follows the diminished 7th. Let's take the example of a dim.7 on G#:

 

We would spell this as G#-B-D-F if the next chord is A minor. As you correctly went on to say, this respects G# as the leading note of A minor.

 

However, if this same dim.7 is followed by a chord of C in 2nd inversion (G-C-E reading upwards) then we would spell it Ab-B-D-F. The Ab in the bass would drop a semitone to G in the next chord. Had we used G# instead of Ab, we would need a second accidental to cancel the sharp for the chord of C. So using Ab reduces the number of accidentals, which in turn helps to make sight reading just a bit easier.


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#12 ThreeQuavers

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Posted 06 September 2016 - 19:30

They come in at Grade 5, and some of my pupils at that level are fairly young, certainly not able enough to be thinking too deeply about exactly how they are constructed. So, we just think of stacks of minor thirds, counting them out chromatically. Or, as one child says, "you just play the next spooky note up and it comes out right."


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#13 SingingPython

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Posted 06 September 2016 - 19:59

Sorry I missed coming back to this earlier.  My comments about playing them on the violin were meant purely as an analogy with learning how to play them "geographically" on the piano; you understand where the notes are in relation to the previous ones.  My hearing/pitch sense never developed enough to appreciate the finer details of enharmonic not-quite-equivalents.


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