Theory Question on this bass line

[Whousedtoplay]

LOL. I guess this really isn't three chord folk music!

Yes and No.
I would say that some chord substitutions could be interpreted by my amateur taste as too ECLECTIC for that
a la Polish Polka track wrapped in the 12-blues form.
I sense some advanced musician got bored with that chord progression and decided to "improve" it.
During my "musically-bohemian" times, I've played with an advanced, conservatory-educated composer who used to apply those "harmonic devices" in very simple pop songs. And I still remember the eyes of our singers while my friend was applying those harmonic tricks.

 

[jdjk7]

Greetings. I am working with a bassline over a gospel style exercise and am wondering about one particular note choice which seems to be out of key. Chart attached.

My assumption on this piece is that it is in the key of Bb. The walk down from measure 17-23 I am assuming is a 5 > 4> b3 > 2 descending line.

My question is why the Db is chosen in bar 21 instead of a D (which I am assuming is in the key). I have drawn a red box around the note in question. Perhaps a b3 for a 3 substitution is common? Or perhaps I have the key all wrong since this is a blues type progression.

Can you help me understand? Thanks so much!

Including the b3, (to a lesser extent) the b5, and the b7-- whether via entire chordal structures or just individual notes-- in a tune that is otherwise in a major key, is a common route to getting a bluesier feeling to the piece. I use it this idea all the time in basslines.

 

[6-3-2]

Notes and chords out of the key are extremely common. Bach did this all the time. If you look at classical sheet music you'll see it constantly too. Usually it's there because it does something interesting or it just feels right with the mood of the song.

However, the others are right, it's a typo here.

 

[Whousedtoplay]

Db in the key of Bb is simply a blues harmonization. It is also a very typical chord progression.

I appreciate your knowledge.
Just a question.
Let's say, an amateur musician like me has decided to reharmonize slightly the OP's track, and
after Db7 go to Cb7 (or B7 for my knowledge) and resolve it to Bb.

Because, "It sounds good" to my amateur ears.

Or, what if after Db7 I play C(natural)7, Cb7 and resolve to Bb.
Would it still be a blues harmonization?

 

[bassfuser]

+1 as a tritone substitution for G7 which is an extended dominant chord. F7 is the dominant of the key, C7 is a secondary dominant into F7 and G7 is an extended dominant into the C7. The Db9 can be substituted for the G7 because the 3rd of Db is F which is the b7 of G7. Also, the b7 of Db is Cb or B which is the 3rd of G7. The other two notes don't really matter because the 3rd and the b7th are the notes that identify the chord type as being a dominant 7th.

 

[Groove Master]

I appreciate your knowledge.
Just a question.
Let's say, an amateur musician like me has decided to reharmonize slightly the OP's track, and
after Db7 go to Cb7 (or B7 for my knowledge) and resolve it to Bb.

Because, "It sounds good" to my amateur ears.

Or, what if after Db7 I play C(natural)7, Cb7 and resolve to Bb.
Would it still be a blues harmonization?

Both would sound good. A chromatic chord progression if fine which is what you suggest. More jazzier but fine too in a blues context imo. The bII7 to I is a great substitution for the V7. So playing a B7 to Bb instead of F7 to Bb is more jazzy and its the bass player note choice that rules LOL.

 

[Don Kasper]

...Db/Eb is NOT a "Db..." chord - it is a shorthand way of specifying the chord "Eb7,9,sus".
The chording instrument(s) is asked to play a "Db triad" voicing, without a LOW Db, as the bass is supplying the lowest Root note of Eb, which causes the combined "Db triad" + "Eb bass note" to sound an Eb7,9,sus.
This type of notation can sometimes be Harmonically Confusing(tm), as it appears to be injecting some sort of "Db...." tonality, but it is simply a shorthand way of specifying a "X,7,9,sus" tonality.
Thanks.

 

[petermwright]

...Db/Eb is NOT a "Db..." chord - it is a shorthand way of specifying the chord "Eb7,9,sus".
The chording instrument(s) is asked to play a "Db triad" voicing, without a LOW Db, as the bass is supplying the lowest Root note of Eb, which causes the combined "Db triad" + "Eb bass note" to sound an Eb7,9,sus.
This type of notation can sometimes be Harmonically Confusing(tm), as it appears to be injecting some sort of "Db...." tonality, but it is simply a shorthand way of specifying a "X,7,9,sus" tonality.
Thanks.

I think the discussion was about the Db9 chord that appears later, not the Db/Eb chord.

 

[BassChuck]

The point of theory is to gain an understanding (in an academic sense) of what sounds good, what doesn't and try to explain why. Theory shouldn't drive musical decisions, what it sounds like is the criteria you use to decide what to play. The mp3 sounds good - I don't hear anything unmusical. That means any discussion is academic, and exists only to explain why it sounds good. If it sounds good (or even if it sounds bad, but it sounds as the composer intended), there aren't (by definition) wrong notes or chords.

Yep. There is it.
Theory is all about what has happened. It might help as a suggestion of things to try, but it should not be the reason you've made a musical decision.

 

[Whousedtoplay]

the Db/Eb chord.

My first time (and most memorable) encounter with that kind of chord "construction" happened many years ago.
It was Joe Walsh & The Eagles - "Rocky Mountain Way."
The bass plays E while the piano and the guitar play D = D/E.
But that time, I did not call that "construction" E7,9,sus.