#1
Hi, first post here.
A couple of days ago, I decided to create a little jam track for myself in ableton live.  I did what I usually do for this: first, I added a little bass loop, basically just going from A to G.   Then I added a drum loop, and then a simple keyboard loop.  For the keyboard, I just added a couple of arpeggios, and A C# D over the A in the bass, and a G B C over the G in the bass part (here's a short mp3 of it: https://soundcloud.com/vthill/agvamp8bars/s-vcexh).  I wasn't setting out to do anything in particular from a music theoretic perspective -- didn't even pay attention to what actual notes I was entering, just doing what sounded good to me.  So now I'm trying to dissect it, and figure out why certain things sound good over it.  Here's what I think I know:
  * it's in the key of D, except for that C in the G arpeggio
  * it sounds good to my ears to play an A minor pentatonic scale over it (which has a C)
  * it also sounds good to play an E Dorian scale over it (that has the C#)

So, my question is, what's going on here from a music theory perspective?  Any ideas?
#2
This is an oversimplification that the jazz police may flash their lights about, but to get started...

It is in the key of A major.
The A major scale is A B C♯ D E F♯ G♯

The two chords are A major and G major.

G natural is not in the A major scale.
G# is in the A major, it is the major 7th.
A B C♯ D E F♯ G♯
1  2  3  4  5  6  7th

G natural is the dominant 7th of A major.

Dominant 7th means "blues and jazz".
Using the G major chord with the key of A major is going to suggest blues or jazz.

The A minor pentatonic is a blues approach to playing over an A -> G cycle.
The E Dorian is the same notes as A Mixolydian.
A Mixolydian is a jazz approach to playing over the cycle.

That's why both sound good, both those blues and jazz scales in A like the A to G cycle.
Quote by reverb66
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#3
Quote by PlusPaul
This is an oversimplification that the jazz police may flash their lights about, but to get started...

It is in the key of A major.
The A major scale is A B C♯ D E F♯ G♯

The two chords are A major and G major.

G natural is not in the A major scale.
G# is in the A major, it is the major 7th.
A B C♯ D E F♯ G♯
1  2  3  4  5  6  7th

G natural is the dominant 7th of A major.

Dominant 7th means "blues and jazz".
Using the G major chord with the key of A major is going to suggest blues or jazz.

The A minor pentatonic is a blues approach to playing over an A -> G cycle.
The E Dorian is the same notes as A Mixolydian.
A Mixolydian is a jazz approach to playing over the cycle.

That's why both sound good, both those blues and jazz scales in A like the A to G cycle.

Wait, doesn't E-Dorian/A-Mixolydian mean that the key is D?  And the G# just sounds bad with the A-G progression.  Unless maybe you're a jazz guy, in which case you could make it sound good .   This article:  http://www.guitarhabits.com/combining-pentatonics-to-play-mixolydian/ talks about combining the major and minor pentatonics for a scale degree (G in his case) to get the mixolydian + an extra note (which would be the C in my case).  I still don't get that though.  I thought you played major pent or minor, not both at the same time?
#4
It has NOTHING to do with E Dorian. E is not a prevalent note

Just because A mixolydian and D major have the same amount of sharps and flats doesn't mean the key is D; again, the main note is A.

A-G vamp has no tonal function and is A mixolydian. G natural is the flat 7 of A (dominant 7 means something else - forget this), and the major chord with flat 7 root suggests mixolydian in a context with major chords

A mixolydian is largely written with the same signature as A major, but all G notes would have natural signs

There are mode threads that might help you navigate modes a bit more. Start from the forum stickies
#5
 Just because A mixolydian and D major have the same amount of sharps and flats doesn't mean the key is D; again, the main note is A. 

But if you say "A mixolydian", doesn't that imply that the key is D major?  if not, then what is the key?  
#6
snowfall62 Hi dude, if we are talking about harmonic context and function, rather than patterns of scales a with accidentals, modes and keys are separate entities.

If you say a song is "in" a mode, it's not in a key, and if it's in a key, it's not in a mode.

Sound confusing and wanky? Yep. But that's what you get for "modal" stuff.
And no, Guitar Hero will not help. Even on expert. Really.
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#7
What key a song/chord progression is in is all about which of the chords sounds like home.

The chord progression of your jam track is A-Asus4-A G-Gsus4-G. So the same thing is first played in A and then a whole step lower. A does sound like the home chord to me so I would say it's in A. Somebody could also analyze it as two separate "keys" (because it's the same idea all the time, just transposed down and up by a whole step). Though maybe in a case like this where the chords are changing quite frequently it would make more sense to just think it as A Mixolydian (because you don't really have time to hear the two chords as separate key centers). Why Mixolydian? Because there is no functional harmony.

I don't think "mode" and "key" are necessarily mutually exclusive. I mean, people usually use "key" in a broader sense to refer to the tonic chord. You could say that something is in the key of Dm when it's actually in D Dorian. The "key of Dm" in this case would just mean that Dm is the tonic chord. Functional (tonal) and non-functional (modal) on the other hand are different things.

So just calling it A major would be pretty accurate too because A major is the tonic/home chord.


If you play a modal tune but want to transpose it so that it fits the singer's vocal range, I'm pretty sure you would say "let's find a key that fits your vocal range". And in this case "key" just refers to the tonic. It is not an argument about whether or not the song uses functional harmony. "Let's play it in another mode" would mean that you would actually change the mode, not necessarily the tonic - i.e., you would change it from major to minor or from Mixolydian to Phrygian.
Quote by AlanHB
Just remember that there are no boring scales, just boring players.

Gear

Bach Stradivarius 37G
Charvel So Cal
Fender Dimension Bass
Hartke HyDrive 210c
Ibanez BL70
Laney VC30
Tokai TB48
Yamaha FG720S-12
Yamaha P115
#8
A progression like that I would simply qualify as A Mixolydian.  For simplicity,  the first line of attack for me is seeing if one mode or scale works over an entire progression - meaning there are no clash notes.  If so, that's my first obvious choice as a point of reference.  I use that in conjunction with where home base feels like. 

Conceptually for me,stating it's in A Major complicates the matter because then you need to worry about changing scales over the second chord ( G maj) - some see this as easy, but for me it's wasted mental energy - plus rarely in a progression like that does A major scale sound good over the 1 chord, it will sound dorky and out of place compared to A Mixolydian ( that's a subjective thing however).  Also, playing A major scale over the D maj chord will  yield the same problem .  Those are stylistic choices however.

Each person has their own way of organizing this information in their head in a way that works for them - some prefer to look at it as a key with accidentals hitting over the off chord, but I find my way simpler, especially when all the chords fit into one sound.  
#9
Quote by snowfall62
But if you say "A mixolydian", doesn't that imply that the key is D major?  if not, then what is the key?  

This is a jargon issue - about defiinition of terms (to help us all avoid talking at cross purposes )

"Key", "scale" and "mode" are three different things.

The set of notes A B C# D E F# G is a "scale". You can write or play those notes in any order, make any chords you like from them. (I just spelled it alphabetically, the first note has no musical meaning.)  
Call it a "pitch collection" if you think "scale" is too definitive.  (The name of a "scale" does often include one of the notes in the name, implying that note has some kind of musical importance - which it usually does, but doesn't have to.)

The "scale" has two common applications: the "keys" of D major and B minor - which mean D and B are "tonal centres".  That means the music will sound like it comes to rest on either one of those notes.  If D "sounds like home", then the key is D.  If Bm sounds like home, then the key is B minor.

D major is a little more common than B minor, so that "scale" (pitch collection) would commonly be called the "D major scale".  That's OK as long as you remember the key could also be B minor.

The scale has other (slightly) less common applications: such as the "mode" of A mixolydian.  A mixolydian means A is the keynote - not D or B.  That makes it sound like the "key of A major", but with a flattened 7th (G instead of G#).

Another common mode of those notes is E dorian, in which E is key centre.  That sounds like the "key of E minor", but with C# instead of C.

Neither A mixolydian nor E dorian (nor B minor) are "in the key of D major".  That's because the latter phrase means D is the keynote.  Those modes just use the same notes - the same "scale".   
It would be nonsense to say "the key of B minor is in the key of D major" (or vice versa)!  Likewise with modes.  They are, in a sense, their own "keys".

Also remember that every pattern of that scale can be used for any mode of those notes.  There is no such thing as a mixolydian or dorian fret pattern (as some guitarists have been led to believe).  They can all be either.

To answer your original question:

I agree with PlusPaul, the keynote sounds like A to me.  But I wouldn't quite call it "key of A major" because of the exceptions he mentions.  There is clearly a bVII chord (G) relative to the A chord.  You're also using a C natural (as you say) in the bass on the G - where your line is G-A-C, not G-B-C as you said.  The G-A-C bass figure is one element which helps confirm A as key note, because it resolves clearly back to A, in a way the A doesn't to G.
The use of both C# and C means you're using a very common principle in rock known as "mode mixture".  Your vamp contains elements from both A mixolydian and A dorian.   It's mostly "A major-ish", but with that distinctive passing C in the bass, adding a brief implication of "A minor".

Now -  none of this fancy theoretical discussion has any necessary bearing on the scales you improvise with!  The simplest view is you just use the notes your chords give you.  That means A-C#-E-G-B-D.  No F or F# is contained in the chords, but F# would be the most likely assumption  (As you've found, that's what sounds best.)  There is certainly no need to worry about what that set of notes is called.  A correct theoretical name would refer to the apparent keynote (A), but whether you call it A mixolydian, D major or E dorian makes no difference to how you play, does it?  It's all the same notes, and I guess you would play off the chord tones as your foundation.   You can then play around with whether (and when) you use C# or C.  Your ear is the best guide there.
It really does no good to imagine one of the notes might be a keynote.  Eg, to think of it as "D major" might make you think you have to emphasise D.  Even to to think of it as "A mixolydian" doesn't mean you have to emphasis A. (And of course the presence of the C means A mixolydian is not the whole story anyhow.)
You certainly don't have to "start" on any of those notes.  
The "keynote" is the note that inevitably emerges as a "home note" as a result of how the chords move.  There's little you can do to stop that being A - although you could underline it.

It may be that you decide to use a different scale on each chord.  You could use G major or G mixolydian on the G chord (both of which contain the C in the bass).  Again, your ear is the best guide.  The theory is only there to help you name whatever you decide the best sound is.  Which takes us back to my opening sentence...  The "rules" are only about what you call things, not how you use those things.
Last edited by jonriley64 at Mar 24, 2017,
#10
^ Good post. Though I do think that knowing what the key is helps you with playing by ear. If I'm trying to figure out a melody by ear, I usually relate everything to the tonic or the chords (that I figure out by listening to their function in the key).
Quote by AlanHB
Just remember that there are no boring scales, just boring players.

Gear

Bach Stradivarius 37G
Charvel So Cal
Fender Dimension Bass
Hartke HyDrive 210c
Ibanez BL70
Laney VC30
Tokai TB48
Yamaha FG720S-12
Yamaha P115
#11
The purpose of a jam track is, as you wrote, to explore "why certain things sound good over it".

I tend to use a "bottom up" approach to hunting for what sounds good rather than a "top down" approach. Top down is looking at chords and finding what lines sound good... I like to play lines and look for chords that make those sound good. I prefer that direction because it results in finding nice and often unexpected chords, which more line playing leads to more chords.

When I play with your jam track I find that there are really no wrong notes if they are done within the context of the right chord substitution or inserted passing chord... and those chords don't need to actually be played because they become implied by the lines.

major sounding

maj7
(6/9)
6sus2

blues jazz sounding

7
9
13

slightly outside sounding

13sus4

Either chord might take the passing chord 13sus4 to to 13
This give it little D->A C->G sound without being obvious

13sus4 -> 13

So for example, things I notice...

- playing lines whose notes come from A major sounds good with the A chord, but not with the G chord. The A major sound "sticks" to the A chord and does not want to carry over for the G chord... the G chord wants its own G major sound. An example of this sound is the intro to "Rainy Night In Georgia".

A Major

A C# E G# B D F#

G Major

G A B C D E F#

- playing lines from A Mixolydian sounds good over both chords, even though it changes its sound with relation to the chords. An example of this sound is the intro to "Head Over Heels" (Tears For Fears) except there the chord movement is reversed moving from the lower chord to the upper chord.

A Mixolydian

A C# E G B D F#

At this point the inquiring musical mind asks leading questions: how come A Mixolydian sounds great over both chords but each of these chords wants its own major scale? Why do the A and G chords refuse to share the sound of A major or G major, but like to share the sound of A Mixolydian?


- I notice lines of A Lydian Dominant notes sound progressively better as the A chord is changed to A7, then A9, then A13, a little outside with the G chord, but the G Lydian Dominant sounds great with the G chord as G13.

A Lydian Dominant

A C# E G B D# F#


G Lydian Dominant

G B D F A C# E

- I notice that the A# Lydian Dominant notes sound good implying a passing chord leading into the A13 (this passing chord could be A#(13) or A#(9b5) or E(#9) or Eaug... Lydian Dominant sounds good over lots of chords).

A# Lydian Dominant

A# D F G# C E G

- At this point I notice that I have found a way to play every chromatic note in contexts that sound good over either chord... and now I really have to cut the yard before it starts raining.
Quote by reverb66
I'm pretty sure the Bible requires that you play through a tube amp in Texas.
Last edited by PlusPaul at Mar 24, 2017,
#12
Thanks for the inputs/advice everyone! It's really helping me to understand what "sounds good" (to me, anyway) & why.