Double Bass F7b5 = B7b5

[Steve Freides]

I'm not always the sharpest tool in the shed when it comes to these things. Tonight, I was playing with the One-Note Samba at the piano. The chord progression at the beginning is, in the Real Vocal Book:

Dm7, Db7, Cm7, B7b5

So I said to myself, "Self," I said, "What if we un-sub-V the 2nd and 4th chords - how would that sound?" You get

Dm7, G7, Cm7, F7

Ok, that sounds fine. But there's this cool line in the original, descending in parallel minor-7ths with the roots. While the roots go D, Db, C, B, the 7ths are all minor, so they go C, Cb(B), Bb, A.

So I said to myself, "Self," I said, "Hot d@#$, that same line is in the un-sub-V'ed version of the chords, too.

Then I said to myself, "Self," I said, "How about making those two M/m 7th chords into b5 chords, so we'd have

Dm7, G7b5, Cm7, F7b5

And then it hit me that B7b5, which is in the original progression, and F7b5, in my un-sub-V'ed version, are the same notes! "D@#$," I said, "Both have an F-A and B-D#, and those are two major third separated by a whole step, right out of the whole-tone scale.

So, that's my evening's discovery, that B7b5 and F7b5 each contain the same 4 notes. (You'd just have to spell the B-D# as C-Eb for the F7b5 chord.)

How many of you figured this out a few decades ago? (Or not.)

-S-

 

[Don Kasper]

 

[Groove Doctor]

those are two major third separated by a whole step, right out of the whole-tone scale.

I was shown this when taught tri tone subs at school from my cousin, who was massively into jazz and later became a pro muso. I definitely wouldn’t have worked it out by myself at that age.

 

[Whousedtoplay]

Dm7, Db7, Cm7, B7b5

I'd like to hear your opinion about the last chord, B7b5.

Here is a slightly different chord progression.

N.B. Your chords indicate the Bb major Key.
My example is in G major.
Instead of B7b5 (after transposing our Ab chords), it would be Bmaj7(#11)/B7(#11).

 

[Steve Freides]

@Whousedtoplay,

#11 is the raised 4th scale degree. b5 is the lowered 5th scale degree. They're the same-sounding note, D-natural or Ebb over the Ab in your key

If you asked me to play the b5 chord, that would be the 5th I'd be using. If you asked me to play it as a #11 chord, in your key, I'd have an Eb in it. In either case the note represented here is the melody note. D-natural is an augmented 4th above Ab. If you spell it as Ebb, it's a diminished 5th, and perhaps it's simply to avoid a double-flat that whoever's done the chord in your key has chosen to call it a #11.

The major 7th chord going to a dominant (major 3rd + minor 7th) chord is just a suspension and its resolution. The G natural is a note in the Am7 chord in the 3rd measure, and Gb is part of the Ab dominant 7th chord. It sounds just fine to hold the G natural over, making a major 7th chord, then "resolving" it on the 3rd beat of the bar.

FWIW, I played it a few times - I like the suspended note when it's part of the #11 version of the chord, with the perfect 5th played an octave lower than the #11. I don't like it as much when the #11 become a b5, which when I play this on the piano, means a different voicing. For me, your way but in my key is

B - D# - F# - A (or A# moving to A), F-natural

and my version would be

B - A - D# - F

but honestly, the more I play every version of this, with and without the P5 in the chord below the melody, and with and without the M7-m7 suspension, I think they all sound pretty good.

-S-

 

[Whousedtoplay]

I like the suspended note when it's part of the #11 version of the chord, with the perfect 5th played an octave lower than the #11.

Thank you for your very informative comment.


Here is a short clip of that beginning chord progression - in G major - with the EQ-ed bass part and slower.
It's from Antonio Carlos Jobim Live.

The bass player plays Eb in the last beat of Ab7(#11).
If it's Ab7b5, then the bass note should/would be Ebb/D(?).

https://www.talkbass.com/attachment...8/?temp_hash=110efa0aeabd89b4ae58113c8caf2128

Here is another short soundclip of the same measures/chord progression from Sergio Mendes Brasil 66.
It's also in G major.
On the last beat of Ab7(#11) bass plays Eb while the piano player clearly accentuates C D natural Gb Ab chord notes.

https://www.talkbass.com/attachment...5/?temp_hash=110efa0aeabd89b4ae58113c8caf2128

 

[IamGroot]

Thanks for sharing.