Terminology 9th vs 2nd

[Dylan Ritter]

So...why is the 9th so commonly referred to as the 9th and not the second? I've noticed it lately even, in e9 steel terms, when referring to the note at the 7th string (first occurance of 2nd/9th in an octave for a given feet). I suspect there is something more to it than arbitrary convention.

Dylan

[Bill McCloskey]

Chords are built on 3rds. 3rd, 5th, 7th, 9th.

[Greg Lambert]

I have always thought it was so because the 9th is a tonal value higher than 8th which seems to blend better than the lower tonal value ,ie 2nd.

[Richard Sinkler]

I have always thought it was so because the 9th is a tonal value higher than 8th which seems to blend better than the lower tonal value ,ie 2nd.

The way I was taught was, if the (in 'E') F# was a whole step above the root, it was a 2nd, and if it were a whole step above the octave of the root, it is a 9th.

[Dave Mudgett]

When stacking 3rd intervals to make a chord, starting from the root = 1, you get 1, 3, 5, 7, 9, 11, 13, and then you get back to the root 2 octaves up. The 9, 11, and 13 intervals are an octave up from the 2, 4, and 6, respectively.

By convention, when there is a 7th interval in a chord, i.e., chords with 2/9, 4/11, and/or 6/13 notes, the chord is generally labeled 9/11/13, whichever is highest.

So, if there's a major 7th interval in the chord, extensions are called maj9, maj11, maj13. If there's a b7th (generally called simply a 7th or dom 7th) interval in the chord is called 9/11/13 or dom9/dom11/dom13.

This is not the only way to construct/name chords, but stacking 3rds is very common, if not dominant, in western music.

[Tony Glassman]

The convention is that the 1,3 &.5 comprise the triad (maj, min, dim or aug). Additional tones are usually added above rather than below the triad tones.....with some exceptions. ( i.e. sus, 7b5 etc)

[Jeremy Reeves]

It's a 9th if there's a 7th in the chord. If not, it's a 2nd

[Dave Meis]

I was taught that any chord extension higher than '7th' *assumes* that the 7th tone is in the chord.. i.e.: a 9th chord has a 7th tone in it.. if you had a 6th chord with the 9th tone and no 7th, it would be a '6 add 9'. It's only a 9th, 11th or 13th IF it contains a 7th tone.. but I've been wrong before!

[Richard Sinkler]

Is this post about a 9th chord as opposed to a 2nd/9th scale tone? As scale tones, if you use string 8 (E) as a root, the 7th string F# would be the 2nd scale tone. The 4th string E would be the octave ( 8 ) and the 1st string F# would be the 9th scale tone.

[Chris Reesor]

The 9th is the same note name as the 2nd, but an octave up. In the same way, the 4th becomes the 11th, and the 6th becomes the 13th.

In chord construction, these are all "extensions" of a 7th chord, minor, major. or dominant.

If the seventh is not present, say you play 1-3-5-9, that is an "add 9" chord.

That 6/9 chord you reference is kind of a special case, Dave. The usual guitar voicing starts with a major third, then becomes a stack of perfect fourths.

C6/9 - C,E,A,D,G.C Note that the fifth does appear but here it is technically a twelve. I haven't tried extending it further since I don't have a keyboard handy and my underarm guitar only has six strings.

[Fred Treece]

So...why is the 9th so commonly referred to as the 9th and not the second? I've noticed it lately even, in e9 steel terms, when referring to the note at the 7th string (first occurance of 2nd/9th in an octave for a given feet). I suspect there is something more to it than arbitrary convention.

Dylan

In terms of steel guitar, it could be that the 7th string of a 10-string E9 pedal steel is referred to as a 9th because it is a carryover from an 8-string E9 tuning common at the dawn of pedal steel that included a low root well as a major 3rd below that F# (E-G#-B-D-F#-G#-B-E, low-to-high), so it was a true 9th chord tone back then.

I think a grip on the low strings of E9 psg (B-D-E-F#) is not a great way to voice a dominant 9th chord, and to my ear it is one of the lesser functions of those strings. But I digress.

To expand a little on Chris’s excellent response - In terms of intervals, the 2nd is a note’s nearest neighbor. A 9th is clear over in the next octave, and cavorts around with 7ths and 13ths to form dominant chord types. The 6ths and the Major 7ths spread vicious rumors about the dominants, and the b5ths are always looking for ways to corrupt them...

[Tony Prior]

sometimes we exert energy trying to figure out the reasoning behind why something is defined.

The Sky is Blue, the Sun is Yellow... Music theory is defined...

It's a language , one we can all understand and relate to. 2nd or 9th, we can't call them both the same thing. The most simple expatiation above, they are an octave apart so they are NOT the same. A reference was required that we can all understand. Otherwise we would have serious conflicts of music.

Years back when I was a Mass Spectrometer Service Engineer we could spend our time trying to understand why electrons of various sizes moved thru the Quadruple at varied speeds or we could just accept that they do. Some other extremely brilliant scientists figured it out and laid the foundation. All I needed to know is, are the Electrons actually making it thru the Quadruple , and if not, something is broken. I didn't need to figure out why those scientists came up with the theory of it all.



Why does that amplifier work and create sound ?

Because its ON...

I would suggest we play and listen rather than trying to figure out why there is even sound in the first place !

Unless of course we are engineers first and players second

[Chris Reesor]

Not a good way to voice a ninth for sure, Fred, but that is because the crucial third, G#, is missing while the often omitted fifth is present. Better to play 9,7,6 and let the bass player do his job. Or 8,6,2 lowered a half,1. Gotta have that tritone, man.

But a point to make here is that one often neither wants or needs to play a fully voiced extended seventh chord on ten string E9. Just look at the frequently used "drop back 2 frets and lower the B string" ninth voicing. In C, at fret 8, play 6,5,4. That's E,G,C. Drop back to fret 6, lower string 5 a half and you've got D,E,Bb. That is the ninth, third and flat seven, the guide tones and the color tone. Ninth chord implied, mission accomplished.

There are many more ways that three notes or even two notes can imply complex harmonies in an ensemble, and very often less is indeed more.

Of course, us U12 guys have more voicing choices.

[Pete Burak]

There's a reason it's not called "Music Fact"!

[Fred Treece]

There's a reason it's not called "Music Fact"!

LOL, Pete.
Yeah, in theory you could have 100 notes in an octave. In that case, a 2nd and a 9th could not be mistaken for being the same.

[Tim Herman]

Read through this thread and find the answer that suits your problem. Then make music with it. Theory is an interesting rabbit hole. If what you find sounds good in the end...Success! (from a theory teacher)

[Jeremiah Wade]

When talking about intervals the 9th, 11th, and 13th are piano terms. Those were extensions played with the right hand. Outdated terms. When talking chords they are the proper names for extended seventh chords. You may even sometimes see the 10th written in some places. The 10th is the third an octave higher. The fifth is stable and is always called the fifth to my knowledge.

[Fred Treece]

9th = 2nd + Octave.

[Chris Tarrow]

The 2nd and the 9th may be the same note, but if you see them on a chord chart they mean different things. Have seen every chord under the sun playing big band jazz, composers are very particular about what's happening in the rhythm section as they don't want anything clashing with the horns.

C2 means 1,2,5 (no 3rd)
C9 means 1,3,5,b7,9
C6/9 means 1,3,6,9 (no 5th)

[Ian Rae]

Composers are very particular about what's happening in the rhythm section.

C2 means 1,2,5 (no 3rd)
C9 means 1,3,5,b7,9
C6/9 means 1,3,6,9 (no 5th)

Thanks Chris - music theory is only useful if it can be put into practice.

I also agree with Fred that the 9th and 7th strings are indeed the 7th and 9th degrees above a low E (which actually exists on an extended tuning).

[Charles Kurck]