Music Theory question - "mutating" chords by moving the bass note?

[Gruuve]

OK, so say guitar or piano is playing a major chord. The bass line starts on the root note, then let's say it moves up to or drops down to a dominant 7th (or any other note that's NOT a chord tone). Essentially, the bass line moving to the dominant 7th has made the major chord "mutate" into a 7th chord (if you put all the notes together, you get the notes in a 7th chord). You could choose other notes for the bass line that mutate the major chord into a 6th chord, sus4, sus2 or add9 chord, etc. (Although you probably wouldn't want to sit on the 4th or major 2nd too long...that would likely clash with the major 3rd in the chord, unless you do it in a different register. I've learned from experience that sometimes a tone in a higher register works nicely but drop it down an octave and it sounds nasty against the chord.) You can do the same sort of thing with minor chords as well of course.

 

The question: What is the correct music theory nomenclature for "mutating" chords by moving the bassline? (Or IS there a technically correct term for this?)

 

TIA!

Dave

[Eric VB]

Inversion.

[alexclaber]

In the key of A, doing so would be written as:

 

A and then A/G

 

which indicates that the bassnote has changed from the root to the note on the right hand side of the slash. This way of writing a chord is called a 'slash chord'.

 

If my understanding is correct, the chord is no longer an A major because the root note is now G, and is more like a Gdim9 (because it contains 1, 2 (or 9), b5, 6 (or bb7)). But A/G is an easier way to write it, particularly as this chord would often be split between the guitar and bass or the pianist's hands.

 

Alex

[alexclaber]

Originally posted by RicBassGuy:

Inversion.

Surely that's when you change the order of the chord tones, rather than adding another bass note which isn't in the original chord?

 

Alex

[Gruuve]

I thought an inversion is when you make a non-root chord tone the root note, not a note that wasn't originally in the chord. Right or wrong?

 

Dave

[...]

Inversions are when another note is sitting in the bottom of the chord. Like the 3rd (1st inversion) or the 5th (second inversion). Adding another note to the chord that wasn't previously there is not an inversion.

[Gruuve]

Originally posted by Bumpcity:

Adding another note to the chord that wasn't previously there is not an inversion.

Thanks Bump...so what is adding another note to the chord that wasn't previously there actually called?

 

Dave

[Eric VB]

Originally posted by Bumpcity:

Inversions are when another note is sitting in the bottom of the chord. Like the 3rd (1st inversion) or the 5th (second inversion). Adding another note to the chord that wasn't previously there is not an inversion.

Agreed; and I like Alex' answer as well.

Originally posted by Dave Sisk:

Essentially, the bass line moving to the dominant 7th has made the major chord "mutate" into a 7th chord (if you put all the notes together, you get the notes in a 7th chord).

Note that here Dave says the chord is no longer a major chord, but a 7th, and the bottom note is the 7th. In that context it's in 3rd inversion.

 

Knowing Dave, I'm pretty sure he's talking from a compositional standpoint, not a performing standpoint. If you're playing off a lead sheet and happen to add a 7th as a passing tone, I certainly wouldn't call that an inversion.

 

However, if you're composing/arranging a piece and purposely put a 7th in the bass -- even if it's not repeated in a higher octave -- I think we're pretty much in agreement that we're dealing with something more than just a passing tone in the bass.

 

If the score calls for the guitar/keyboard to play A C# E and G in the bass, it is certainly valid to call that an A7 in 3rd inversion, no?

 

If you want the guitar to play an open A chord (E string muted, A E A C# E) and G in the bass, then the slash notation Alex mentions seems reasonable, and we call it a day. No need to worry about what the actual chord is other than "A/G".

 

[besides, I was trying to show that I actually can make a succint post. ]

[Gruuve]

Oh...now I see how you arrived at this as an inversion. So, for instance, a 7th chord with the root as the dom 7th would actually be an inversion...agreed.

 

I probably didn't really use such a good example above to get the spirit of the question across. Let's say the piano is playing a major chord, and you do a bass line of quarter notes at a fairly slow tempo that starts on the root, moves to the dom 7th, then to the major 6th, then maybe back to the root or to the 5th. So, on count 1 it's a major chord, on count 2 it's got the notes that would make it a 7th chord, on count 3 it's got the notes that would make it a major 6th chord, then it resolves back as a major chord. You sit on those tones long enough for it to define a harmony change, so it's more than just a passing tone. For the moment, forget about what the root note of the chord actually is (say you're playing way up high on the bass, or say you're even using a guitar instead of a bass)...you've used some notes that aren't in the original chord to cause it to become a different chord temporarily (until you resolve it).

 

So, I guess in more general terms, my question is actually if there's a technically correct name for causing the chord to become a different chord by moving one note (and not necessarily just the bass note, although that was my original thought). This is almost contrapuntal or counter melody type of movement, but not entirely.

 

Oh, and thanks for helping me figure out what my question actually is!

 

And yes, this is more from a compositional standpoint. I'm looking to put some study into this area, but I don't know what exactly to search for since I don't know what it's technically called! I know some study in walking bass lines is along the same lines, but I'm actually looking at from a more general perspective (applicable to bass, but not necessarily just related to bass guitar)

 

Dave

[jeremy c]

The correct term for playing a measure in which the bass player plays the first bass note as the name of the chord and then plays other notes in the rest of the measure is:

 

Playing a bass line.

 

If you want to write something specific for the bass player to play you could write:

1) notes on music manuscript paper.

2)something like this:

 

|C C/B C/Bb C/A|G G/F# G/E G/D|

 

some of the above combinations are inversions and some are not. A bass or keyboard player should know what to play when reading chord changes that look like that.

[Gruuve]

Originally posted by jeremy c:

The correct term for playing a measure in which the bass player plays the first bass note as the name of the chord and then plays other notes in the rest of the measure is:

 

Playing a bass line.

 

Well...there ya have it. Question answered I think. (In other words, there is no theory-specific name for it, other than maybe walking bass line or similar.)

 

Dave

[TimR]

The question has been answered but as an extra, the exact wording I would use when describing A/G would be "A with a G bass."

[...]

Originally posted by TimR:

The question has been answered but as an extra, the exact wording I would use when describing A/G would be "A with a G bass."

Pretty much just that. Usually I hear and/or say something like: "A7 over G" "A7 with G in the bass".

[Eric VB]

Originally posted by Dave Sisk:

This is almost contrapuntal or counter melody type of movement, but not entirely.

You could think of it that way.

 

It's almost as if you're taking an orchestral score and arranging it for small ensemble. Give the 1st and 2nd violins, viola and cello to piano, and give bass to bass. It's not often that the non-bass parts would be so harmonically static, but nobody said they had to have interesting parts.

 

For some reason this discussion reminded me of Pachelbel's Canon http://en.wikipedia.org/wiki/Pachelbel\'s_canon. However, upon further inspection, the basso continuo is playing root on every chord. Still, the analysis on Wikipedia is worth a quick read.

 

Sometimes when I compose I have similar chord changes (as Dave describes) in the chordal instrument (typically guitar but sometimes piano). I'll at least grab that "defining" note at some point in the bass line to emphasize it -- don't we all? -- but I can't think of anything off hand where I've used bass to change the chords as Dave first described.

 

I'd guess the Keyboard Corner folk might have some interesting input, as they are usually fairly well steeped in theory.

[Tom Capasso]

I'm not the best when it comes to theory, but it seems that we're blurring a line.

 

If the sounds being made are 4 notes that form a 7th chord, it's a 7th chord that's inverted. That's from a theoretical viewpoint. It treats it as if it was planned out this way.

 

But that's not how this really it happens. And because of the voicing and different instruments, we look at it from an "arrangement" point of view, which is A/G.

 

And when you do this live - not preplanned - it seems like it's an arrangement more than something you did to cause a theory situation.

 

I play from chord charts in church, and see lots of the "slash" based bass notation. Maybe that's why I think of it as an arrangement kinda thing.

 

Tom

[BenLoy]

If the non-root note in the bass is in the chord, it's an inversion.

 

If the non-root note is not in the chord, it's a substitution.

 

F'instance, if you play a C# under a G7 chord, you're playing a b5 substitution and changing the chord to C#7b5 (or C# half-diminished). Something like this usually works best if your next chord is going to be a C7.

[PhilMan99]

I'm not schooled in music theory, but a lot of the Church music I play has "chord charts" with the "slash notation" (like A/G).

 

Sometimes the "bass" (G above), rather than a common root/3/5/7 is a 2nd or a 4th and it really makes a difference. Just last week, I was driving the guitars *nuts* by just "jamming" in the current chord, rather than emphasizing the bass-note in the "slash chord".

 

Live-n-learn; I'll be watchin' them "slash" notes (bass-notes) on the chords now...

[Davo-London]

Slash chords are lot of fun to play on guitar often causing really difficult fingerings. That's why the guitarst will be so grateful if you play the bass note as written!

 

I personally adore D/F# and A/C# chords on guitar.

 

Davo

[Eric VB]

Originally posted by PhilMan99:

Just last week, I was driving the guitars *nuts* by just "jamming" in the current chord, rather than emphasizing the bass-note in the "slash chord".

In my church ensemble, ignoring the slash note often leads to disagreement with the piano arrangement. Better to double the piano's left hand in that case than to freely improv.

 

Sticking to the arrangement as written is usually a good thing for ensemble performances. It can be embarrassing to step on the violin lead when trying to avoid clashing with the piano.