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Bdim7 in bar 6 of an F Blues

Discussion in 'Music Theory [DB]' started by Don Kasper, Jan 23, 2020.

  1. Don Kasper

    Don Kasper Supporting Member

    Overflow from another Theory thread regarding Diminished Scales.
    How do you approach the Bdim7 chord that often occurs in m.6 of a Blues in F?
    In my teaching, this is one of the first encounters with a Passing Dim7 chord, and most students are befuddled and unfamiliar with the sound, function and notes of a Bdim7 scale/chord. (B,C#,D,E,F,G,Ab,Bb,B - Please hold your A# comments... I don't roll with a written A#.)
    See m.6 below - I like using this portion of the Bdim SCALE (the Whole/Half version) to return to the F7.
    I'd be interested to see other examples of Scale-based choices on that chord, in that measure.
    (Some students CAN outline the Bdim7 arpeggio, but only 4 notes - there are 4 more notes that are available and work beautifully. I think it is my job to make sure they are aware of the whole enchilada.)
    Last edited: Jan 24, 2020
  2. Wasnex


    Dec 25, 2011
    I might play Bdim7 chord tones, or use a partial whole/half diminished scale, or sub in G7b9. B, D, F G sounds nice as long as no one blows a gasket because you land on A on the down beat of of an F7. If someone gets bent out of shape, B,D,G,F# will take you to the F and sounds like a tritone sub.
    vilshofen likes this.
  3. Tazziedevil


    Apr 2, 2019
    I’m not sure I totally understand the question, but when I play the Dim7 in bar 6, I’ll usually play the B natural on the 1 and then some kind of rhythmic arpeggio based on a G7b9 to make it stand out from the Bb the previous measure.
  4. I know this is going to sound weird, but give it a chance:

    In this progression, I view the Bdim7 as a IV chord with a sharp 1. So I set up a chromatic bassline with it—Bb to B to F/C (then a passing tone C#) to D7.
  5. Tazziedevil


    Apr 2, 2019
    That’s not weird! That’s exactly how I think of a Dim7 chord in this context.
    instrumentalist likes this.
  6. dkziemann


    Dec 13, 2007
    Rochester, NY
    Endorsed by D'Addario
    Great question! I agree with Don, the B diminished scale works just fine.

    When I walk in that part, I have two go-to ideas (depending, of course, on the context). First is I treat it as an F blues sound (Ab and Cb bringing out the blues flavor).

    More commonly I think about it as a variation of a V-I in the key of F. Since the movement of Bdim7 to F7 is technically a V-I movement—though not as apparent as C7-F—I'll play other colorful V-I ideas that focus on the half-step-below resolutions. This includes E7-F or Abº7 to F. (Yes, they're essentially the same).

    For example, here's an E7 in place of Bdim7. I've also included a variation in a second example, thinking of Abdim7. It's basically the same, but gets me hearing slightly different target notes.

    |Bb7 / / / | Bº7 / / / | F7
    |Bb - C - D - F | G# - B - E - D| C [Bb7 to E7]
    |Bb - C - D - F | G# - F - E - D| C [Bb7 to Abdim7]

    The G# would begin on the G string, moving up to the high E in the neck block position.

    It's a bit of an old-school harmonic approach, and I find it both creates melodic contours and forces students to consider all of the fundamental harmonic options before considering other substitutions. Plus, that "E" at the top of the line is sweet.

    My two and a half cents...!
    Last edited: Jan 24, 2020
  7. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator Gold Supporting Member

    Oct 19, 2000
    Louisville, KY
    Like Danny, I think of it in several ways. The primary way is that the Bo7 wants to lead to F7/C, so the voice leading of the line would lead there. I also hear the "IV7 chord with a raised root" approach mentioned earlier, since every dominant chord can be seen as a diminished chord waiting to happen (i.e. - raise the root and it becomes a o7 chord); but in this case I still hear it wanting to resolve to the C in the line pretty strongly.

    For the rest, since the o7 chord is symmetrical, the only thing that tells us what the root is is the way it's written on paper. Aurally, it could have four names, depending on resolution, with any of the notes of the chord except F being a leading tone to a chord tone of F7 (i.e. - B-->C, D-->Eb, Ab/G#-->A ). This opens up the possibilities of the resolution unless you are in a situation where for whatever reason you must play the root on the downbeat of every chord change or face dire consequences.
  8. dkziemann


    Dec 13, 2007
    Rochester, NY
    Endorsed by D'Addario
    Right on the Money—great explanation

    Sometimes the importance of diminished chords can be glossed over. Their overwhelming flexibility might put some people off, but they can also reinforce the harmonic strength of a bass line so well! Just listen to Ron Carter walk on Autumn Leaves from the Miles 1964 YouTube video. Diminished chord heaven. I digress...!
    Chris Fitzgerald likes this.
  9. Steve Freides

    Steve Freides Former Mannes College Theory Faculty Supporting Member

    Dec 11, 2007
    Ridgewood, NJ
    That looks like a treble clef there, son.

  10. Steve Freides

    Steve Freides Former Mannes College Theory Faculty Supporting Member

    Dec 11, 2007
    Ridgewood, NJ
    I agree.

    Does it need to be more complicated than that? It seems a voice-leading thing. A two-voice "slither" if you will, everyone moving by half-step.

    Listing bass note first, it's Bb + Ab, B + Ab, C + A.

    And other things, too. I hear the D in the first two bars wanting to go to C as a middle voice, so Bb + D + Ab, B + D + Ab, C + C + A.

    And all three bars have an F in them, so it becomes a 4-voice Bb + D + F + Ab, B + D + F + Ab, C + C + F + A, and you have 4-note chords and Bob's your uncle.

    Chris Fitzgerald likes this.
  11. Don Kasper

    Don Kasper Supporting Member

    How embarrassing...
    This has been corrected.
    Thank You, Steve.
    Steve Freides likes this.
  12. Steve Freides

    Steve Freides Former Mannes College Theory Faculty Supporting Member

    Dec 11, 2007
    Ridgewood, NJ
    It's OK if I don't write something about reading different clefs now, isn't it? I mean, there's a whole, good lesson about the history of notation, moveable clefs, and the like.

    NVM, this is good: Clef - Wikipedia

    You ain't wun a them gitar playuhs, iz ya? We don't like their kind in these parts.

    Quinn Roberts likes this.
  13. Them there's fightin' terms! :bored: :laugh:
    Steve Freides likes this.
  14. Pat Harris

    Pat Harris Supporting Member

    Nov 17, 2006
    Austin, TX
    All those notes you play over a Bb7... keep them all, except play a B-natural instead of Bb.

    B - C - D - Eb - F - G - Ab
  15. Steve Freides

    Steve Freides Former Mannes College Theory Faculty Supporting Member

    Dec 11, 2007
    Ridgewood, NJ
    @Pat Harris and everyone else, FWIW, I would mostly play an arpeggio here because those are the notes that jibe with the voice-leading aspect of this. For me, I would avoid any sort of C and any sort of E; Bb, D, F, Ab, and G in between the F and Ab sound fine to me.

    I have nothing against fish and reptiles, but sometimes I'm against scales.

    Just my opinion, your mileage may vary.

    longfinger and dkziemann like this.
  16. About this point, Bdim to F7 is a common tone prolongation, not a leading tone resolution. It is basically, F7-Fo7-F7. It's a I - i - I movement (came from common pedal root/bass note and melodic lower chromatic neighbours for the 3rd and 5th) and not a V-I movement. Dominant - tonic would be F - Eo7 - F


    Nice lines. I'll steal them. ;-)
  17. Carl Hillman

    Carl Hillman

    Jan 1, 2010
    B whole|half diminished really sounds best there to my ears, and yes, the chromatic bass motion up from Bb to Bo7 to F7/Cbass is usually what I emphasize when walking.

    When soloing though, I sometimes think of that change as E13b9#9 leading to the F7 in the next bar. Same diminished scale, just a more "functional" way of looking at it as a tritone sub of Bb7 and half-step-below leading chord going to the F7.

    Six of one, half dozen of the other...
    Last edited: Jan 24, 2020
    Jason Hollar likes this.
  18. Most times, I just play the B twice for the 2 feel, and arpeggiate the chord for walking. If I do a scale, I'd use a fragment pf the B H/W diminished scale because it shares many common tones with the key. (B, C, D, Eb, F.. and then I'm on to the next chord.)

    I use much the same approach as "dreamadream99"
    It all works, but after a dozen chorus is can be repetitive! So these other sounds you're bringing here can help shake it up. The B diminished W/H is real nice as the C# and E wakes the listeners up, something is different. I'll use this more..

    Thing is, I hardly ever think of scales when playing bass. Thinking chord tones is so much more effective for me. 4 quarters to the bar, and a chord to the bar, means 4 notes per chord, so I don't need to think of all the 7 notes. I focus on the bottom tetrachord of the scale, or the top tetrachord. There can be 3 different scales sharing the same bottom or the same top, and if I'm only playing 4 out of 7 notes, those differing 3 notes are not relevant to me at the time. (ie. in the OP's written example, the 4 notes {B minor tetrachord} could belong to multiple scales, 3 kinds of B minor, B Dorian, B diminished W-H and many more. 4 notes can't define a 7 note scale)

    But, as chorus after chorus goes by, that kind of thinking can give out repetitive sounds. So it is nice to practice and hear these things.
    Last edited: Jan 24, 2020
  19. Dude here, "You're not wrong, Walter....". Attacking a superimposed chord like that with an entire scale shouldn't be plan A.
    As always, the question needs to be "what notes?" not "what scale?". The second question needs to be "what is happening in the melody (this goes for a solo by another musician as well).
    If it is just hanging a chord a tri-tone away from the root in form as common as the blues, the implication is that said form is strong enough to hold it, so, the bass player can carry on playing an F blues with open ears.
    @Don Kasper's written line is a great one, and similar to what I might play in that context. However, I would see that chord as primarily being about movement, and the moving chromatic line would make sense there. Also, that line makes fine sense if it was still a Bb7.
    Unless the soloist or melody was really digging in it, I wouldn't deal with it harmonically. If they were digging in, their involvement might still be enough - if I didn't have anything to add, I'd just keep things moving.

    The most important thing I ever learned in a jazz bass lesson from the great Bay Area jazz bassist Michael Jones, is that Jazz is about movement, after the 1 you are on your way to the next chords. Checking in at the fixed points is what it is about, not dwelling in the chord.
  20. Now, I'm excited to mix and match Bo7 and C#o7 arpeggios in that measure. Yes, those notes form the 8 note B diminished W/H scale, but I find it more useful to stack them in 3rds instead of 2nds and use them that way.

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