Scales

Any scale that doesn't clash with the chord tones will work.

In your G major progression, you have:
G (G-B-D)
C (C-E-G)
D (D-F#-A)
so if you line them up in a row, you're using:
G-A-B-C-D-E-F#-G
which is a G major scale.  That's why it works over any chord in the progression -- no scale notes will clash with any chord notes, no matter where you are in the tune.

The pentatonic G minor has a Bb note in it... this sounds ok, because it creates a 'bluesy' sound against the G major chord.

A mixolydian scale/mode lowers the seventh tone of the major scale with the same name (or starts on the fifth note of the major scale a fifth below), so your D mixolydian contains:
D-E-F#-G-A-B-C-D
these are exactly the same notes as the G major scale, but with a different tonal center.

Your instructor is basically telling you to use G major scale tones througout, but to center your melody around D during part of the progression.

Tom

That makes sense. Let me see if I can explain this question then. I know how the major scale in G covers the entire fret board. I also see where the mixolydian mode fits into that scale and that the root note to that mode is on the tenth fret, or D. Could I then just use the mixolydian mode with the root note on the third fret and just play G mixolydian, or any mode for that matter with the root of G. I realize it would restrict the notes, I'm just trying to get a feel of the modes. I've been using the G minor pentatonic over the progression and feel pretty comfortable with it up and down the fret board now, it's just a little confusing with the modes in the major scale. Thanks for your help.

Modes are probably one of the most confusing things for guitarists... and it's a really no wonder, since most of the stuff written about them seems to be by people who don't understand them (or to be more charitable, maybe they do, and just can't communicate it well).

A mode is just a major scale with a different tonal center -- it doesn't start and end on the keynote.

The easiest way to illustrate this is to listen to something in C major and then to something in A minor.  They sound like very different keys, but they have identical notes, and identical key signatures.

C major is the Ionian mode of C, and A minor is the Aeolian mode of C.

The other modes are more subtle than the C/Am relationship, but it's the same principle: center your melody around a different tone, and it will have a different feeling.

If you know the G major scale up and down the neck, you know all the notes in A dorian, B phrygian, C lydian, D mixolydian, E aeolian, and F# locrian.  It's just a matter of centering your melody around the tone you want (ok, that's a bit easier said than done, but all things come with practice!)

If you use G major scale notes centered around the 10th fret of the 6th string, you're playing in D mixolydian.  If you move that scale fingering down seven frets, you're in G mixolydian, which is relative to C major.  That shouldn't restrict the notes at all... it just moves all your fingerings down seven frets, or up five.

Tonally, what you're doing is going from this scale:

D-E-F#-G-A-B-C-D, which is W-W-H-W-W-H-W

to this one:

G-A-B-C-D-E-F-G, which is W-W-H-W-W-H-W

Since the interval patterns remain the same, you're still in a mixolydian scale, just with a different keynote.

Tom

Think I got it. I was getting the key of the mode confused with the key of the major scale. In the key of C you would have D dorian, E phrygian, F lydian, G mixolydian, A aeolian, and B locrain. Is this correct?

You got it!

Actually, Locrian isn't a traditonal mode (the monks who created this system didn't use a scale from the seventh), and I refer to it more often as a 'leading tone scale' than a Locrian mode, but you have the concept down!

For the most part, I stay away from thinking about modes.  I shift tonal centers all the time, but after a while it becomes second nature to you.... I don't think "I'm gonna move from C Ionian to C Mixolydian", I think "I'm about to move into F... I'm gonna flat the B".

In my opinion, people give WAY too much importance to modes.  Sure, learn them.... understand what they do... anticipate the sounds they make... but then just make music :)

Tom

I'm a little fuzzy on this whole "clash" thing...
Any scale that doesn't clash with the chord tones will work.

In your G major progression, you have:
G (G-B-D)
C (C-E-G)
D (D-F#-A)
so if you line them up in a row, you're using:
G-A-B-C-D-E-F#-G
which is a G major scale.  That's why it works over any chord in the progression -- no scale notes will clash with any chord notes, no matter where you are in the tune.

Okay so is the 4th a passing note over the G chord?

Is the Lydian just 'flat out' the better choice over the I chord?

If this example you've posted illustrates that "no scale notes will clash" then can you illustrate and example of one that does contain notes that clash?

I've always been a bit fuzzy on this.

Not a problem...

You've got an underlying chord, like G.  Your melody note is creating intervals with each of the chord tones.... le'ts say you've chosen Bb in the melody.  You've now got:

G to Bb
B to Bb
D to Bb

all happening at the same time.  The G to Bb gives you a minor third interval, the B to Bb (enharmonic = B to A#) gives you a major seventh interval, and D to Bb (enharmonic = D to A#) gives you an augmented fifth interval.

There aren't any intervals that can't be used; each has its own effect on the listener.  Some theorists have tried to set out hierarchies of all the intervals, moving from consonnance (don't clash) to dissonance (clash).

In general, the intervals that don't clash are perfect unisons (you play a chord note), perfect octaves, perfect fifths, and perfect fourths... although many theorists will treat a perfect fourth as a dissonance if no fifth is sounding in the chord.  These are called perfect consonnances, and are the 'best' sounds for pleasing the ear.

Next you have imperfect consonnances, which are major and minor thirds and sixths.

All the other intervals have some degree of disonnance... major and minor seconds and sevenths, all the augmented and diminished intervals.

You want your solos to have variety to the ear, so all melodies will have a mix of consonnances and disonnances.  You just don't want to overwhelm your listener with too many dissonances (which sounds 'bad') or too many consonnances (which sounds 'sappy').  Tastefully done, just about any scale can be used over just about any chord, as long as it's done for intentional effect, so there's no 'flat out best' scale for any single chord or change.

As far as the 4th being a passing tone, it could be... or you could treat it as a suspension.  In a harmonic suspension, you're playing a non-chord note (C against the G major chord) and holding it through the chord change so that it becomes a chord tone.  If your accompaniment goes from G major to C major, and you hold the C through the change, it's resolved from a 4th to the root of the new chord, and it sounds just dandy without being a passing tone.

To see how some scales work better than others, let's say your chord is G, and we'll limit the scale choices to G major and G locrian.  Both have a G root... here's how the created intervals line up against the G chord on each scale degree, with dissonances in bold... inversions can get confusing, so I'm counting UP from the melody note to each of the chord tones here:

..................G major.............G locrian

1 (G/G).......P1-M3-P5...........P1-M3-P5
2 (A/Ab).....m7-M2-P4...........M7-A2-A4
3 (B/Bb).....m6-P1-m3...........M6-m2*-M3
4 (C/C).......P5-M7-M2...........P5-M7-M2
5 (D/Db).....P4-M6-P1...........A4-m7*-m2*
6 (E/Eb)......M3-P5-m7..........P4*-A5-M7
7 (F#/F)......m2-P4-m6..........M2-A4-M6

* - enharmonic equivalent

You can see there's a lot more dissonance with the locrian... every note except the root will form at least one dissonance, and two notes will be dissonant against ALL the chord tones.

That's essentially the 'why' of some scales working and others not.

Tom

Thanks Noteboat. I agree with you about the modes. I learned the major scale over the fretboard and knew where the modes fit in, just didn't understand how or why. Makes sense now. Now I can get back to making music with them. Thanks again.

Cool,thanks NoteBoat!

You really DO need theme music...

ok, here we go...

these are in step intervals

Ionian mode =
Major scale -(W W H W W W H)

Dorian mode =
same as the Major scale starting on the 2nd note.
-(W H W W W H W)

Phrygian mode =
same as the Major scale starting on the 3rd note.
-(H W W W H W W)

Lydian mode =
same as the Major scale starting on the 4th note.
-(W W W H W W H)

Mixolydian mode =
same as the Major scale starting on the 5th note.
-(W W H W W H W)

Aeolian mode =
same as the Major scale starting on the 6th note
-(W H W W H W W)

Locrian mode =
same as the Major scale starting on the 7th note.
-(H W W H W W W)

is this right?

Yeah, you're right.  Another way to approach this is by thinking of modes as altered major scales.  For example, the Dorian mode is a Major scale with a lowered 3rd and 6th.

na na na na na na na na noteboat! (batman theme melody)*shines "?"*

okay,some more (possibly stupid) questions on scales: do all scales have to consist of the same number of notes? Do all scales have to end on the root note, or can a scale cover several octaves before it hits it's root?how do I apply scales to chord progressions? Ive always just started on any random note that sounds alright, and went along and just played a few different patterns that dont sound bad. Ive been doing the right stuff, in all likelyhood, but I want ot understand how it works. Thanks.

do all scales have to consist of the same number of notes?

Of course not.  The major and minor scales have 7 notes, pentatonic scales have 5, the blues scale 6, bebop scales 8 and so on and so forth.  In theory, any number from 2-12 is possible.  

See http://www.geocities.com/scaleopia/ for a completely pointless compendium of scales.
Do all scales have to end on the root note, or can a scale cover several octaves before it hits it's root?

A note and its octave are for all intents and purposes, the same note.  It is inconceivable to me at least how a scale could include a note, but not its octave.   Or the 2nd, but not the 9th.  I may be thick but I just can't wrap my brain around that concept.  
how do I apply scales to chord progressions? Ive always just started on any random note that sounds alright, and went along and just played a few different patterns that dont sound bad. Ive been doing the right stuff, in all likelyhood, but I want ot understand how it works. Thanks.

Hmmm.  If they're in the same key, the scale and chord progression will fit together. If not, it depends on individual notes and the way they fit with the chord of the moment.

Let's say the chord of the moment is a C major.

It contains the notes C, E and G.  Those notes will fit seamlessly and in fact hardly be heard against the background chord.

Otherwise it depends on the consonance/dissonance of the intervals the note in question forms with the chord tones.

Note of course that dissonant intervals like the minor 2nd can be resolved in a pleasing way and this is the guiding principle in western music.

For example, a C# (minor 2nd) will sound nasty against our chord.  It will grate against the C and we will be happy when it leaves.  Some may be able to use this to advantage in composing.  

A D (2nd) will sound nasty, but much nicer if we play it an octave higher ( as a 9th) so that it doesn't grate so against the C and E.  It will also sound better if me remove the E, making a Csus2 chord.

A D# (minor 3rd) will rub against the E a semitone uo and also form an augmented 5th (b6) interval with the G, both very dissonant.   In the next octave up as a #9 it will sound much nicer and is much used in blues.  A dom7 with a #9 is is often called the "Hendrix chord".

An F (perfect 4th) is dissonant with the E but again sounds better in a higher voicing as an 11.  

And so forth.  

Here's a table of the various intervals and how they sound: http://www.chordwizard.com/hmw301.asp

I was taught that the octave was 8 notes higher than the root note. 12_3_4_5__1 repeatedly will hit the root two octaves higher than the root. it ends on 3.
try it on your geetar and you might get it... thats how I thought this whole stupid thing up. I dont know if that can be considered a scale or not...

[glow=red,2,300]I am a retard. Pay no heed to my retarded and confuzing rambling[/glow]