# Music Theory Question

Discussion in 'Tab, Tips, Theory and Technique' started by Cloodie, Dec 19, 2020.

1. ### CloodieTele-Meister

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Recently I've been looking to build on my knowledge and add 9ths and 6ths into my blues playing. The part I'm struggling with is understanding why the 9th isn't just called the 2nd. I've read stuff about how it's to do with building chord voicings and them being based on stacking thirds to make chords but does this also apply when discussing scales?
For example, if I'm playing the A minor pentatonic scale and I play the root note on the 10th fret and the 2nd string, then I'm playing the B on the 2nd string 12th fret, in what way is this different, if at all, from just calling it the 2nd rather than the 9th? I've read there can be a difference in sound between a 9th and a 2nd but how can that be possible here as it's not as if you're playing it up an octave?

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2. ### DjimiWreyTele-Holic

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i've asked myself that question as well,
as a person with no formal training and not a lot of self taught theory study either
9th, 2nd to me are just contextual a little bit like G#,Am
so i just assumed the 9th was the same note in the next octave up from the 2nd just above the root?

3. ### hnryclayTele-Meister

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It's the octave from the root, which is on the 12th fret of the A string in that position. Even if you pickup the scale on the B string at the 10th, the root for that position does not change. That is my understandong of fretboard theory. All scales are based on root notes from the E, A, or D strings. No matter where they are picked up.

4. ### theaterguyTDPRI Member

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Yes 9th is same as 2nd technically but a X9 chord has to have a 7th and a X13 chord has a 6th. So math goes like 2+7=9 and so on.

Cadd2 has C, D, E and G
Csus2 has C, D and G

5. ### Mark the MooseTele-Afflicted

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It used to be standardized, then the internet happened.
The 9th implies the presence of a 7th.
So G9 is G-B-D-F-A.
G2, however, implies a missing third: G-A-D...sort of like how a sus chord has a 4th and no 3rd. This is sometimes erroneously called a Gsus2, but it’s not really a suspension.

Further complicating things is the word “add”.
Gadd9 or Gadd2 mean the same thing: full triad with no 7th but add a 2nd or 9th, G-B-D-A. Whether you called it a 2nd or 9th depended whether you came from a jazz or rock background. Jazzers always called it a 9th, rockers were more likely to call it a 2nd. This is likely because the jazz world had more people trained in classical harmony.

Then the internet happened and it became the Wild West, now nobody knows what you really mean when you say G9 on a chord chart.

6. ### -Hawk-Friend of Leo's

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I’ve always referred to it as the 2 when in the context of a scale.

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7. ### ndcasterDoctor of Teleocity

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it's the same note, but as others have said, up one octave

as for it sounding different, I would say yes because a 2nd is often treated more like a suspension, an "inner voice," than a 9th, which is an "extension" and more often treated like a color or melody note

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8. ### Mark the MooseTele-Afflicted

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I would respectfully disagree. Once we agree on the pitch classes, the chord voicing is entirely up to the player. Whether the 2 or 9 is voiced internally or not doesn’t connect to the analysis of the note.

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9. ### JamesAMTele-Meister

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Yep, the number is relative to tonic (of the chord, not the song). How you choose to invert it doesn’t matter- you could play the 9 as a 2 in your voicing, but there should be a 7 in there also to make it a true 9. I thought your previous explanation was perfect!

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10. ### ndcasterDoctor of Teleocity

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your explanation of what we mean by "a ninth chord" was spot on, but I was responding to this:

"I've read there can be a difference in sound between a 9th and a 2nd but how can that be possible"

the only way I could make sense of that possibility is by thinking about voice leading

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11. ### Mark the MooseTele-Afflicted

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I’m simply stating there is no difference in the analysis based on where you position the note. Thus a 2nd or 9th are both an A in the key of G and can be placed anywhere above the bass. Extra octaves above the bass don’t make one a 9th and the other a 2nd. The difference in sound is reflective of what other notes you use.

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12. ### Leon GrizzardFriend of Leo's

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Just to add that G9 means implied b7; a dominant chord, as opposed to a major 7, which would be called GM9 or GMaj9. But you're a blues guy so it prob'ly don't concern you much. lol

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13. ### MiddlemanFriend of Leo's

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It's a tonal thing. Not a numbers thing. You are looking for that 2nd above the octave and as others pointed out the 7th.

It's a bit clearer on piano.

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yep

15. ### hepularTele-Afflicted

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With ya on this: if we're going to be consistent, the #s should refer to where the note is relative to what we're specifying as the root. Just because lots of folks have accepted the current convention as normal doesn't automatically make it correct. SO . . . forthwith, we will all start using the following system i just made up: instead of the really confusing count in 8 (or is it 7?): intervals an octave above stay the same, but get a ' (prime) symbol" so the 9th would become 2' the 10th 3' etc. Going all Eric Johnson or Holdsworth & slapping 2 octave extensions? 2" etc.

But what about inversions? Negative #s: first inversion, then = -3 1 5.

Thank you for adopting this contribution to musical nomenclature so quickly & without fuss

16. ### rough eyeTele-Meister

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listen to The Moose. he got it right.

all you need to know is 2 = 9, 4 = 11 and 6 = 13.

big difference between a C6 (C E G A) and C13 (C E G Bb D F A) chords - the "13" implies that the 9 and 11 are also present. I think this is more obvious n a piano, where you can actually play a 7-note closed voicing.

so a 9th chord has the 1 3 5 7 9 and an 11th chord has the 1 3 5 7 9 11. On guitar we decide which notes to leave out. OR, we learn when we see a C9 we play an Em7 (over a C bass note), when we see C11 we play a G7 over C - this is how it's taught in jazz piano.

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17. ### Larry FDoctor of TeleocityVendor Member

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I know you hoped to glide over this, but it will be entertaining watching how you go about dealing with it.

Just joking. Seriously, though, is this being used outside of classical?

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18. ### Junkyard DogFriend of Leo's

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I'm not really a blues scholar/expert, but...I don't even think there is supposed to be a B note in the A minor pentatonic scale.

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19. ### jbmandoPoster Extraordinaire

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I disagree that sus2 is erroneous. Sus2 means the third is absent. 2 or add 2 means the third is there. The same terminology applies with the 4. G(4) means the 4th is added to the triad. Sus4 means the 3rd is absent. Many sources, including this forum, use sus2 for a chord consisting of the root, 2nd and 5th.

Last edited: Dec 19, 2020
20. ### klasainePoster ExtraordinaireSilver Supporter

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Those designation numerals are really only used for chord spelling.
A 9th is always above the 5th, 6th, 7th, octave.
If you want that note somewhere between the lowest root and the 5th, then it can be called the 2nd.

In the universe of professional music arrangers, editors and copyists, an add9 chord is 1, 3, 5, 9.
An add2 chord (as Jb just mentioned) is a triad with the 2nd in there between the 1 and the 5 (fielder's choice).
sus2 like sus4 implies no 3rd - usually 1, 2, 5 ( Asus2 - X X 7 4 2 X) and then maybe resolving the 2 (or 4) to the 3. Starting in May of 1965, sus chords ceased having to resolve.

A plain 2 chord such as A2 has no 3rd and no resolution. In guitarland that 2 can be anywhere. The most common voicing for us is: X 0 2 2 0 0 (A E A B E). *No other instrumentalist would voice it that way though (unless they play guitar, maybe?).
A guitar player usually writes A2, a keyboard player usually writes Asus2 (or sometimes Aadd9no3 ).

Nomenclature evolves as music evolves.
Chord symbols with numbers to express extensions and alterations is a relatively new development and even within my lifetime I've seen it evolve and I still run into discrepancies. An example would be A7susb9 or 'A phrygian' chord. Amaj9#11 or 'A lydian' chord. Is an Amaj7b5 the same as an Amaj7#11. Does one imply that the natural 5 is potentially present - ?

Melodically it doesn't really matter; 2/9 or 6/13 - all good.
If you're expressing the contour of a line, for example in A minor: A, C, E, G, B ... I would numerically spell that 1, b3, 5, b7, 9 (not 2). The B note is above the octave.

Last edited: Dec 19, 2020
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