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Thread: Choosing Between Enharmonic Equivalents

  1. #1
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    Choosing Between Enharmonic Equivalents

    1) On what factors should my choice between enharmonic equivalents be based? Key, scale, mode, chord, where the melody or harmony has just been and where it is going, a combination of these, something else completely?

    2) And as a follow up, regarding where the melody or harmony is coming from and where it is going, and choosing between enharmonic equivalents; is this only important when changing from one key to another?

  2. #2
    bitter old fool Jed's Avatar
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    Quote Originally Posted by TJM View Post
    1) On what factors should my choice between enharmonic equivalents be based? Key, scale, mode, chord, where the melody or harmony has just been and where it is going, a combination of these, something else completely?
    The general rule that I follow is to make every attempt to stay "in key". When there are harmonic accidentals they are often based on a secondary or extended dominant - So I try to use the key of the target when determining between enharmonic options. Melodic accidentals are easier in that you stay in key as long as possible and use sharps for passing tones that resolve upward and flats for passing tones that resolve downward.

    Quote Originally Posted by TJM View Post
    2) And as a follow up, regarding where the melody or harmony is coming from and where it is going, and choosing between enharmonic equivalents; is this only important when changing from one key to another?
    Sorry I don't really understand what you are asking.

    Typically we notate with an eye towards making the music easy to read so in general we try to minimize the number of sharps or flats when choosing a key signature. Once the key sig is determined, then I try to keep all following notation and symbols make sense from the perspective of that key. If the song modulates then we have to decide how best to notate the new key all over again. I hope some of that helps.

    cheers,

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    Quote Originally Posted by TJM View Post
    1) On what factors should my choice between enharmonic equivalents be based? Key, scale, mode, chord, where the melody or harmony has just been and where it is going, a combination of these, something else completely?

    2) And as a follow up, regarding where the melody or harmony is coming from and where it is going, and choosing between enharmonic equivalents; is this only important when changing from one key to another?
    I'm not 100% sure what you're asking, but this recent thread discusses some of the rules for handling accidentals when notating melodies.

  4. #4
    Registered User Brent2013's Avatar
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    Quote Originally Posted by Jed View Post
    The general rule that I follow is to make every attempt to stay "in key". When there are harmonic accidentals they are often based on a secondary or extended dominant - So I try to use the key of the target when determining between enharmonic options. Melodic accidentals are easier in that you stay in key as long as possible and use sharps for passing tones that resolve upward and flats for passing tones that resolve downward.



    Sorry I don't really understand what you are asking.

    Typically we notate with an eye towards making the music easy to read so in general we try to minimize the number of sharps or flats when choosing a key signature. Once the key sig is determined, then I try to keep all following notation and symbols make sense from the perspective of that key. If the song modulates then we have to decide how best to notate the new key all over again. I hope some of that helps.

    cheers,

    Another thing, besides it being easy to read, as well as staying in key, is to avoid contradictions. Example, sharps in flat keys. in the key of Eb the 2nd tone isn't F# it is Gb. Likewise in the key of B a flat 2nd tone (or C note) would be called B#

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    Registered User Malcolm's Avatar
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    If you are looking for something to keep you on the right track here is THE simple "rule"......

    1. Account for all letters.
    2. Don't duplicate letters.
    3. Don't mix sharps or flats in the same scale.
    4. After you have done that - then allow for the exceptions, i.e. the Blues Scale, etc.


    There are always exceptions.
    Last edited by Malcolm; 03-07-2011 at 06:42 PM.

  6. #6
    Registered User JonR's Avatar
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    Quote Originally Posted by Brent2013 View Post
    Another thing, besides it being easy to read, as well as staying in key, is to avoid contradictions. Example, sharps in flat keys. in the key of Eb the 2nd tone isn't F# it is Gb. Likewise in the key of B a flat 2nd tone (or C note) would be called B#
    Just to complicate things, annoyingly...
    There are exceptions in a couple of minor keys. Eg, in the key of D minor, which has a Bb, there will be a C# leading tone. Likewise in G minor (2 flats in key sig) there is an F# leading tone.
    The rule is still "one of each note".

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    Follow up

    Thank you all for your time and helpful feedback!

    My goal was to get a better grasp on the use of enharmonic equivalents/spellings and yes I see how the proper use of accidentals is very important in that.

    This seems to be important in at least two areas, modulation and chord substitution. I am new to all of this so any more thoughts that you want to throw out is great.

    Thank you, again.

  8. #8
    Registered User Color of Music's Avatar
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    JonR's probably gonna roll his eyes (lol); however, this doesn't mean that you can't have opposite accidentals. With scales - and their exceptions, but you mentioned chord substitution.

    That depends on the function or relationship - not with the key (scale), but the chord before and after it.

    CMaj9-C#dim-Dm9-G7#5b9-CMaj9. That's correct; however, so is this:

    CMaj9-Dbdim-Dm9-Db9 (Fm7b5/Db)-CMaj9. Fm is not in C#, but Db is. VI or I with VI as the bass note. Again, that's scale, but here's where the function comes in:

    In the first progression, we have: I-#idim/ii-V-I

    In progression two, we have: I-biidim-ii9-bII9-I.

    bII = subV; Db = G. Both notes can swap for one another in the bass.

    There is a tri-sub for C# = Abb; however, most don't write double-flatted chords. Nor do scales see a #1. (C# is this in C) Very often they see the b2 (Db in C) CPP says Db doesn't exist in C and it doesn't, but extend it; therefore, changing the function and it does!

    I most certainly wouldn't write Bbb, Db, F - just because I have flats in my KS. Often times, you find double-flats on the last note of chords - particularly diminished ones whether triads or sevenths (and the latter are "serious" trouble!)

    Nor would I write C#dim, just because my KS has sharps. Accidentals don't have to be restricted to KS; however, when doing analysis (at least for me), unless it's absolutely necessary to use the key accidental, I'd use the opposite one.

    #I = bII
    #II - bIII
    #IV = bV
    #V = bVI
    #VI = bVII

    The flatted intervals are considered borrowed chords/tones (III, V, VI and VII; II is simply is tri-sub, but comes from a scale, too. I forget which, atm)

    bIII, VI and VII the natural minor scale
    bV = the Diminished scale
    #IV = the Lydian scale (more mode than scale)
    #V and VI = the Augmented scale

    Again, you'll probably see the former four more often than the latter three, but this doesn't mean the latter three are not seen. I used to use #IV (because it made more sense), but went to bVs because of clarity (and making more sense - to me at least) And if you were to analyze this way:

    C-Ab-G-C. I-bVI-V-I vs. C-G#-G-C - I-#V-V-I. The G in the second progression would need a natural. We could slide since we're in C, but let's do this in Db.

    Db-A-Ab-Db. I-bVI-V-I vs. Db-Gx-Ab-Db. Let's make it worse: Db-Gx-G#-Db. Even if the Is were C#, you'd still prefer A (bVI) over Gx (#V). Would you not?

    The other reason, flats are used is to give a sense of movement. Look at the above progressions again. 1-b6-5-1. Even the 1-x4-5-1, sees a little movement. 1-#5-5-1, doesn't - at least from an analysis perspective.

    You can get movement with sharps.

    C#-A#m-D#m7-G#7-F#m9-G#7b9-C# (I-vi-ii-V-iv-V-I)

    However, if we change a couple of chords:

    C#-A#m-D#m7-G#7-B13sus-B9-C# (I-iv-ii-V-bVII ... I)

    Why is that a bVII as opposed to a #VI - despite being correct an "restricted to the KS?"

    But there is no rule that says that you have to stay within the KS. I've seen D#'s in the key of Eb; however, I wrote a B chord instead of a Cb chord. Again, there's no rule, just something to be aware of.

  9. #9
    Registered User JonR's Avatar
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    Quote Originally Posted by Color of Music View Post
    JonR's probably gonna roll his eyes (lol);
    Here ya go:

    Your posts often inspire me to excessive lengths, and this is no exception. It's not that much of what you say is wrong, exactly (IMO some of it is), more that a lot of it is not clearly expressed, so I'm not sure exactly what it is you are saying.
    I'm afraid much of the following - which extends to two parts! - may be a critique of your English, rather than your theory (which is generally good, actually, at least as far as I know (or care)).
    Quote Originally Posted by Color of Music View Post
    however, this doesn't mean that you can't have opposite accidentals.
    If you mean there are many different rules governing enharmonic choices (some possibly contradictory), I agree...
    Quote Originally Posted by Color of Music View Post
    With scales - and their exceptions, but you mentioned chord substitution.

    That depends on the function or relationship - not with the key (scale), but the chord before and after it.

    CMaj9-C#dim-Dm9-G7#5b9-CMaj9. That's correct; however, so is this:

    CMaj9-Dbdim-Dm9-Db9 (Fm7b5/Db)-CMaj9. Fm is not in C#, but Db is.
    That sounds a little like a confusion between notes and chords (potentially anyway).
    C# (note) is not in F minor (scale/key);
    Db (note) is in F minor (scale/key;
    Fm (chord) is not in C# major (key);
    Fm (chord) is in Db major (key).
    (I think that covers it

    Question is, how do these facts impact on the above progression? "C#dim" is quite correct, because its target is Dm. C# is the leading tone of the D minor key, and C#dim is the vii chord in D (harmonic) minor.
    Dbdim is therefore incorrect.
    It's not even a corerct chord symbol in any other context - if we're being strictly correct with our chord spelling. (I know we went through this in another thread .)
    In relation to F minor (key), you have a Db note in the Edim7 (vii) chord. But putting Db in the bass doesn't make it a "Dbdim7" chord.
    It's a very narrow (pedantic) point but relevant IMO to a discussion of enharmonic niceties.
    In any case, the key of F minor is irrelevant in this sequence.
    There is no way, therefore, that Dbdim7 is justified as a chord symbol - either in this example, or in any I can think of. (It might sometimes be OK, between friends , but not theoretically justifiable.)

    When it comes to Db9 (Fm7b5/Db) that's a different matter. Db9 is the tritone sub for G7 (in the given key of C major). C#9 would not be exactly incorrect, IMO, but Db9 is better.
    That means, in this sequence, you'd have a C# bass note (C#dim), then (after D) a Db bass note. Nothing wrong with that, and perfectly correct - even (coincidentally) following the rule about ascending and descending chromatics.
    Quote Originally Posted by Color of Music View Post
    VI or I with VI as the bass note.
    How does that relate to the above sequence? There is no VI chord.
    Quote Originally Posted by Color of Music View Post
    Again, that's scale, but here's where the function comes in:

    In the first progression, we have: I-#idim/ii-V-I
    Nope. We have I - vii/ii - ii - V - I
    Quote Originally Posted by Color of Music View Post
    In progression two, we have: I-biidim-ii9-bII9-I.
    "bII9" yes, but "biidim" is a pointless symbol. It doesn't reflect the function of the chord, which is a leading tone chord for the next one. It just highlights the fact that "Dbdim7" is a wrong symbol. IOW, an enharmonic error. The correct enharmonic (C#) reflects the chord function.
    Quote Originally Posted by Color of Music View Post
    There is a tri-sub for C# = Abb
    That might as well be G, IMO. Is there a reason to make it Abb? That's neither a diminished 5th nor an augmented 4th. (Some would say that only an aug4 can be a tritone, because it's three separate tones; I wouldn't go that far myself .)
    Quote Originally Posted by Color of Music View Post
    ; however, most don't write double-flatted chords. Nor do scales see a #1. (C# is this in C) Very often they see the b2 (Db in C) CPP says Db doesn't exist in C and it doesn't, but extend it; therefore, changing the function and it does!
    Not following your grammar there...
    But there's no rule why C# (or any other chromaticism) can't appear in key of C.
    Quote Originally Posted by Color of Music View Post
    I most certainly wouldn't write Bbb, Db, F - just because I have flats in my KS.
    In what situation would you need Bbb and not A? (There are some, I'm just not sure what you're thinking of.) [Scratch that - one crops up in part II..]
    Quote Originally Posted by Color of Music View Post
    Often times, you find double-flats on the last note of chords - particularly diminished ones whether triads or sevenths (and the latter are "serious" trouble!)
    Yes, if you build dim7 chords - strictly correctly - on notes which are not normally dim7 roots.
    Such as "Cdim7". Strictly that would be C Eb Gb Bbb.
    But Cdim7 would imply the key of Db minor, which in any practical situation is C# minor. (I can see a context, theoretical at least, where a Db major key might change to its parallel minor...but I don't really want to think about it .)
    "B#dim7" might look like a stranger chord than Cdim7, but it's the natural vii chord in the key of C# minor (4# key sig). The B# note exists in two normal major keys. Bbb doesn't exist in any normal key. It could well exist as a passing chromaticism, I guess, but would still be rare.
    Quote Originally Posted by Color of Music View Post
    Nor would I write C#dim, just because my KS has sharps. Accidentals don't have to be restricted to KS;
    Right. The choice is nothing to do with the key sig, only with the chord function.

    [cont below...]

  10. #10
    Registered User JonR's Avatar
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    [Part II...]
    Quote Originally Posted by Color of Music View Post
    however, when doing analysis (at least for me), unless it's absolutely necessary to use the key accidental, I'd use the opposite one.
    Always? Why?
    Quote Originally Posted by Color of Music View Post

    #I = bII
    #II - bIII
    #IV = bV
    #V = bVI
    #VI = bVII

    The flatted intervals are considered borrowed chords/tones (III, V, VI and VII; II is simply is tri-sub, but comes from a scale, too. I forget which, atm)
    If you mean bII, the tri-sub doesn't come from a parallel scale, because it's a dom7.
    In key of C major, Dbmaj7 could be said to be borrowed from parallel phrygian (or even locrian), but that's not a tri-sub for G7.
    Db7 is not a borrowed chord, because its scale doesn't feature C.
    Quote Originally Posted by Color of Music View Post
    bIII, VI and VII the natural minor scale
    "b" in each case, yes.
    Quote Originally Posted by Color of Music View Post
    bV = the Diminished scale
    Locrian too. Gb major in key of C comes from C locrian (Db major).
    It could also come from the C HW dim scale, but I don't know if that counts as a scale one can borrow chords from.
    Quote Originally Posted by Color of Music View Post
    #IV = the Lydian scale (more mode than scale)
    Yes, if you mean F#m7b5, although that's much more likely to functioning as a secondary ii chord, heading for Em via B7.
    Quote Originally Posted by Color of Music View Post
    #V and VI = the Augmented scale
    This is definitely getting confusing...
    When we talk about "borrowing", we mean chords, not just notes.
    Chords can be borrowed from any scale which features the tonic as a scale note. Just to lay out the full number for C major:

    Db(maj7): C phrygian or locrian
    D(7): C lydian (but would more likely be a secondary dominant)
    Eb(maj7): C aeolian or dorian
    Eb(7): C phrygian
    F7: C dorian (common in F blues too, of course)
    Fm: C aeolian or phrygian
    F#dim (m7b5): C lydian (but see above)
    Gb(maj7): C locrian
    Gm: C aeolian, dorian or mixolydian
    G(maj7): C lydian (pretty unlikely)
    Ab(maj7): C aeolian
    Ab(7): C locrian (but often used in C minor blues)
    Bb(maj7): C dorian or mixolydian.
    Bb(7): C aeolian.
    Bm: C lydian.

    There would be others if you include harmonic and melodic minor scales (not to mention diminished, augmented or harmonic major), but the major scale modes are by far the most common source of borrowed chords (in major keys anyway).
    In rock, borrowed chords are usually triads, so the 7/maj7 distinction doesn't arise. Generally "borrowing from the parallel minor" (aeolian) is the common rule.
    Quote Originally Posted by Color of Music View Post
    Again, you'll probably see the former four more often than the latter three, but this doesn't mean the latter three are not seen. I used to use #IV (because it made more sense), but went to bVs because of clarity (and making more sense - to me at least)
    But it always depends on context. There is no rule saying that bV is better than #IV, even most of the time.
    Quote Originally Posted by Color of Music View Post
    And if you were to analyze this way:

    C-Ab-G-C. I-bVI-V-I vs. C-G#-G-C - I-#V-V-I. The G in the second progression would need a natural.
    OK, now you're talking notes. Yes, this is the ascending/descending rule, and is about avoiding unnecessary accidentals as you say.
    Quote Originally Posted by Color of Music View Post
    We could slide since we're in C, but let's do this in Db.

    Db-A-Ab-Db. I-bVI-V-I vs. Db-Gx-Ab-Db.
    Whoah, Db-A-Ab-Db is I-#IV-IV-I. I-bVI-V-I would be Db-Bbb-Ab-Db. (There's that Bbb finding its niche! )
    I don't quite get the point of calling A "Gx". It's never going to be a likely scenario! (Not in this key anyhow.)
    Quote Originally Posted by Color of Music View Post
    Let's make it worse: Db-Gx-G#-Db. Even if the Is were C#, you'd still prefer A (bVI) over Gx (#V). Would you not?
    Of course, but not because of double sharps/flats. The bVI chord in C# major is A major; not Gx. I see no reason to invoke a "#V" chord.
    However, the note Gx is required in the key of A# minor (relative minor of C# major), and might be a common occurrence in C# major.
    Quote Originally Posted by Color of Music View Post
    The other reason, flats are used is to give a sense of movement. Look at the above progressions again. 1-b6-5-1. Even the 1-x4-5-1, sees a little movement. 1-#5-5-1, doesn't - at least from an analysis perspective.
    I think what you're getting at is the idea of resolution. Classically, chromatic resolutions need to be between different notes: Ab to G, not G# to G. G# would resolve to A.
    That does govern some enharmonic choices. (Eg in augmented 6th chords.)
    Quote Originally Posted by Color of Music View Post

    You can get movement with sharps.

    C#-A#m-D#m7-G#7-F#m9-G#7b9-C# (I-vi-ii-V-iv-V-I)

    However, if we change a couple of chords:

    C#-A#m-D#m7-G#7-B13sus-B9-C# (I-iv-ii-V-bVII ... I)

    Why is that a bVII as opposed to a #VI

    - despite being correct an "restricted to the KS?"
    (last sentence confusing)
    Quote Originally Posted by Color of Music View Post
    But there is no rule that says that you have to stay within the KS. I've seen D#'s in the key of Eb
    Example? (I don't disbelieve you, but I'd like evidence )
    Quote Originally Posted by Color of Music View Post
    ; however, I wrote a B chord instead of a Cb chord. Again, there's no rule, just something to be aware of.
    Actually there is a perfectly good rule why you wrote B instead of Cb.
    The chord is the bVII of the key (sub for the previous minor iv, itself borrowed from C# minor). Why call it a "bI"? Makes even less sense than writing it as "Ax" (#VI).

  11. #11
    Registered User Color of Music's Avatar
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    I always do that! Thanks for corrections again.

    And yes, I was getting to resolution.

    I don't know of any score or such, maybe I shouldn't have said that. I was just re-stating that you don't have to stick to the KS - I probably should've added within reason.

    The last sentence was highlighting this: In D, I have C7#5b9. C (natural) 7 - which is right, but analysis wise, it bVII. Dominants have the bVII, no, regardless of KS, no?

    Regardless of this, whatever is used varies from person to person.

    Btw, I didn't expect you too do that. Thanks for humoring me.

  12. #12
    Registered User JonR's Avatar
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    Quote Originally Posted by Color of Music View Post
    I always do that! Thanks for corrections again.

    And yes, I was getting to resolution.

    I don't know of any score or such, maybe I shouldn't have said that. I was just re-stating that you don't have to stick to the KS - I probably should've added within reason.
    Yes. The point is there are many rules governing enharmonic choice. KS is only one of them, and won't govern every instance. But there are rules; I'm not sure I can think of a situation where there would be no preference either way.
    Quote Originally Posted by Color of Music View Post
    The last sentence was highlighting this: In D, I have C7#5b9. C (natural) 7 - which is right, but analysis wise, it bVII. Dominants have the bVII, no, regardless of KS, no?
    Yes - assuming you mean "b7" . "bVII" refers to a chord or scale degree, not to a chord tone.
    Those alterations would be unusual on a bVII chord, however. bVII chords are usually lydian dominant - they don't have to be, but that's the "common practice".
    But let's say you have a C7#5b9: the chord would normally determine the enharmonics: Bb, G#, Db. But the context (melody, chords before or after) might mean the other enharmonics might make more sense - be more legible.
    Altered chords are one of those grey areas, in fact. As (usually) V chords in minor keys, a "#5" would be enharmonic with the b3 of the key. If that C7#5b9 were in the key of F minor, it would seem crazy (in a melodic line over that chord) to notate G# instead of Ab. Likewise a "#9" on the chord might make more sense - again in a melodic line - written as Eb than D#. (Although a b9 would be nothing but Db, of course.)
    Quote Originally Posted by Color of Music View Post
    Regardless of this, whatever is used varies from person to person.
    Maybe - but it really shouldn't! Music theory and notation has to be a universal language, as far as humanly possible, otherwise there is really no point in it. It's about enabling musicians to communicate effectively with one another, either via words (terms and concepts) or notation. That's not possible if two people mean different things by the same term, or use different terms to mean the same thing.
    There are some variations in the conventions, that's true, especially when it comes to jazz, pop and rock practices. But where there are traditional rules that can be applied (if there is no better, widely understood alternative), they should be.

    Of course, many (if not most) rock players know little theory, and I guess many are tempted to invent their own terms or explanations for things. But those private languages shouldn't be regarded as equally valid as the traditionally accepted one.
    Obviously playing styles and musical choices "vary from person to person" - as they should. But we have to share a common theoretical language; ignorance of it doesn't mean it doesn't exist .

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