Question with modal progressions! John???

[Cary Chilton]

Hiya everyone! It has been a bloody year since being here and I what the hell have I? Well, playing my nuts off, making the best improvements of my natural life in guitar variety! Seriously at the woodshed, daily. Not unheard of to sweat it in a 4-10 hour session. Smallest being 1-2 hour practices. Learning covers. WRiting. Working on timing, which is a NEVER-FREAKIN-ENDING endeavor.... but I am happy,......

 

Ever-forward!

 

Well I seem to johnnypac ( I bought his book actually) and john I believe is his name on my theory questions.

 

I want to ask what is the best way to approach modal progressions. That is, a chord progression with the distinctive sound of a particular mode. For instance, with Phrygian, it is typical to base the progression on the 1st b2 and b3rd for it's Egyptian character.

 

However, what about other modes? I have been told to basically use a I IV V or I vi IV V .... is that all that is available?

 

Also what recommendations for natural minor Key progressions are there? Not quite the same as a simple modal progression, since Aeolian is a natural minor key.

 

Thanks

[JonR]

I want to ask what is the best way to approach modal progressions. That is, a chord progression with the distinctive sound of a particular mode. For instance, with Phrygian, it is typical to base the progression on the 1st b2 and b3rd for it's Egyptian character. However, what about other modes? I have been told to basically use a I IV V or I vi IV V .... is that all that is available? Also what recommendations for natural minor Key progressions are there? Not quite the same as a simple modal progression, since Aeolian is a natural minor key. Thanks

The best way to construct modal sequences is to think of two chords: one "key" chord, and a contrasting one that will resolve to the key chord and can contain distinctive modal notes that the key chord may lack.

IOW, this other chord acts rather like a "dominant" acts in a key-based progression - although that's not really the correct word (sometimes a "subdominant" is a better comparison),

There's a few ways of approaching it, but here's some ideas. In all of these, you can assume the two chords alternate, but the first chord may need more time spent on it than the second.

 

Ionian: I-IV

Dorian: i-IV, or i-ii

Phrygian: i-bII

Lydian: I-II, or I-vii *

Mixolydian: I-bVII

Aeolian: i-bVII

 

The lydian ones are either the Phrygian or Mixolydian pair the other way round, so its important in these cases to spend more time on the key chord.

 

Alternatives:

 

Ionian: I-ii (make sure you spend more time on I)

Dorian: i-bVII (needs either a 6th on the i or a maj on the bVII to differentiate it from Aeolian)

Phrygian: i-vdim

Mixolydian: I-bVII-IV (make sure you spend more time on I than the others)

Aeolian: i-iv, i-bVII-bVI (ditto)

 

Mixolydian and Aeolian are strong enough to be able to take 2 addtional chords, as long as the I chord is underlined enough.

NB: Aeolian mode is different from the minor "key" because the latter has a major V chord (from harmonic minor). Stick with chords from natural minor and you should be OK, but watch out for a tendency to pull towards the relative major (best avoid the bIII chord altogether).

 

Locrian won't work with any other chord, and its own "key" chord is unstable anyway (any other chord harmonised from the mode will sound more stable). IOW, probably not worth bothering trying for a Locrian vamp or composition at all.

(But if you want to take that as a challenge...)

[Cary Chilton]

THanks JonR~ So you suggesting modal chord progressions should best be with vamps -2 chords? I also read somewhere using the differentiated modal character chord as a slash, can highlight the modal feel. D Dorian - Dm7/A - G/A

 

 

 

I understand Lydan bII is unique to Lydian as is vii (more subtle) but why include the #IV?

 

Hmm interesting about Dorian's i-IV or i ii but to chain 3 chords and showcase the i and 3b and VIIb?

 

I understand Phrgyian's unique i-bII, III - vdim is interesting to note!

 

Not quite sure I understand the Mixo prog I bVII IV -can IV come before?

 

Aeolian i-iv is unique isn't i bVII bVI the typical British metal progression (however metal is power chords) ? So, i bVI bVII too weird? Why does i bVII bVI feel better?

btw Can I IV V approach be used for Aeolian ?

[JonR]

 

btw Can I IV V approach be used for Aeolian ?

Yes. I should have mentioned that, because it would be very common.

 

Just make sure all the chords are minor (Am, Dm, Em for A aeolian). The A minor key will use E or E7, which is how you tell the difference between A aeolian and the A minor key.

[Cary Chilton]

 

Just make sure all the chords are minor (Am, Dm, Em for A aeolian). The A minor key will use E or E7, which is how you tell the difference between A aeolian and the A minor key.

 

 

A minor has major E or Edom??? Where/when did that get standardized?

[JonR]

What I mean is the typical minor key progression: i bVII bVI --- Em/D/C usually in power chords Nearly every Iron Maiden song, lots of Judas Priest songs.

Yes, but if they're power chords, they're neither major nor minor. So that would be E5/D5/C5. If it's Em, it's not a power chord!

Usually the implication of any power chord is that it's standing for major anyway.

I'd need to see more of the chord progression to say whether a tonic power chord could be said to be major or minor (or is genuinely ambiguous).

Generally speaking, heavy rock prefers major chords as tonics, despite all that borrowing from the parallel minor.

 

[cont. below]

[JonR]

A minor has major E or Edom??? Where/when did that get standardized?

Oh, only a few centuries ago...

The conventional minor key - as used in classical, jazz, pop and a lot of rock music - takes its V and vii chords from the harmonic minor scale, and its other five from natural minor.

So the key of A minor will contain Am, Bdim (Bm7b5), C, Dm, E, F, G#dim7, as a standard chord set. No G. (The presence of a G would suggest a modulation to the relative major, C.)

E7 and G#dim7 come from A harmonic minor, and are there to strengthen the cadence to Am by providing the G# leading tone; both have a "dominant" function, IOW.

 

Rock minor keys have their own conventions, and a typical set of chords in A minor in rock would be Am, C, Dm, E, F, G. No Bm7b5 and G instead of G#dim7 - but still E major.

Sometimes you also find a D or D7, which you could interpret as coming from A dorian or A melodic minor. But Em would be relatively rare - rarer than E major anyway.

 

Classic rock minor key songs include House of the Rising Sun, Hotel California and Sultans of Swing.

All have major V chords, and HotRS and HC also have major IV chords. HC is a fancier sequence and modulates to the relative major in the chorus.

Chords in HotRS: Am C D F E (key A minor)

Chords in HC: Bm F# A E G D Em (key B minor, modulating to D major)

Chords in SoS: Dm C Bb A F (key D minor, modulates to F)

 

Sultans uses the classic "Andalusian cadence" (common in flamenco): Dm-C-Bb-A. (A major, not Am .)

[Cary Chilton]

Your a WEALTH of song writing knowledge Jon! I feel guilty getting all this information! hehe

It is a little bit much to digest, so maybe I will my next posts case/song specific until I digest and ask about harmonic minor, melodic minor, Jazz minor and it's uses... 3 cans of worms ...rain cheque

 

I am surprised those mixolydian examples vary wildly in sound. Most are darker sounding in general. Any thoughts what makes them differ so much?

Anymore rock, classic rock, metal examples?

 

I'd like to ask about all the modes, but one at a time....

 

Addressing Natural minor - I am curious if you know why the powers of the day, picked Aeolian to modify for a stronger tonal center and use as the Major key's compliment? Why didn't they pick Mixolydian or Dorian? Since, as you say modal progressions are basically vamps because of it's weak tonal center, why did they decide to alter aeolian instead strengthening the tonal center of another? Just to be clear, an Aeolian modal progression is really not a key and cannot really use a whole lot of chords, rather its modal progression is really no different in use to another mode, correct? I would like to ask about stellar examples of the use of song writing, say as in the Beatles, Major /w minor key chords vs minor key /w Major key - but in the future.

 

 

 

and your examples, below:

 

 

Rock minor keys have their own conventions, and a typical set of chords in A minor in rock would be A, C, Dm, E, F, G. No Bm7b5 and G instead of G#dim7 - but still E major.

Sometimes you also find a D or D7, which you could interpret as coming from A dorian or A melodic minor. But Em would be relatively rare - rarer than E major anyway

 

Amajor? Why? Also, isn't G7 from Cmajor anyway, why G#dim7 ?

 

 

Classic rock minor key songs include House of the Rising Sun, Hotel California and Sultans of Swing.

 

All have major V chords, and HotRS and HC also have major IV chords. HC is a fancier sequence and modulates to the relative major in the chorus.

Chords in HotRS: Am C D F E (key A minor)

 

 

i III IV (why Dmajor?) VI V

 

 

 

Chords in HC: Bm F# A E G D Em (key B minor, modulating to D major)

 

i #III VII IV (again why major?) VI iv

 

 

 

Chords in SoS: Dm C Bb A F (key D minor, modulates to F)

 

Sultans uses the classic "Andalusian cadence" (common in flamenco): Dm-C-Bb-A. (A major, not Am .)

 

what is the common Andalusian cadence? I haven't heard of it! hehe

[JonR]

I'd like to ask about all the modes, but one at a time.... Addressing Natural minor - I am curious if you know why the powers of the day, picked Aeolian to modify for a stronger tonal center and use as the Major key's compliment? Why didn't they pick Mixolydian or Dorian?

Good question. I can only guess, but AFAIK it works as follows:

 

WARNING: potted history lesson follows, no doubt including lots of debatable generalisations...

 

Firstly, the "powers of the day" began as the Catholic church, which (around 600 AD) wanted to rationalise its worship music to underscore its international power. It didn't want local churches just making up their own songs from local folk tunes or whatever! It wanted everyone - literally - singing from the same hymn sheet.

The system they chose was based on the old ancient Greek modal system, but adapted and simplified.

 

The four governing modes in the pre-key modal era (from 600 AD to around 1500) were Dorian, Phrygian, Lydian and Mixolydian (and their 4 "plagal" variants). Ionian and Aeolian were not used.

To begin with, there was no harmony. Singing was in unison.

Look up "Gregorian chant", named after the pope who got the whole show on the road.

Harmony began with "organum" (2 lines at the same time, in perfect 4ths or 5ths only).

But increasing developments in harmonising the modes meant certain notes were habitually altered, primarily to avoid the tritone.

If you were in Dorian, and an F-B interval threatened to turn up, they'd lower the B to Bb. Which makes what we would call Aeolian mode .

If you were in Lydian, and an F-B interval threatened to turn up - guess - they'd lower the B to Bb. Making what we'd call Ionian (F major).

If you were in Mixolydian, and that tritone reared its ugly head, they'd raise the F to F# (to resolve home to G). Making - you guessed it - Ionian again (G major).

In Phrygian (and I have to say I'm not totally sure about this) they might also raise the F to F# to avoid the tritone and resolve to G (rather than lower the more important B) - arriving again at something like Aeolian.

 

So you can see that all these alterations to the traditional modes ended up at arriving at sounds that were already built-in to Ionian and Aeolian modes. The latter were therefore an accident waiting to happen, as it were. (Ionian was apparently resisted for a long time because it was popular with troubadours and folk musicians. And we know the traditional church response to rock'n'roll... plus ca change...)

 

Ionian turned out to go perfectly hand-in-hand with the developing concept of triadic harmony. That nasty tritone could actually be used, and well managed without alteration, because it resolved neatly to the root and major 3rd of the tonic chord. (F-B goes outward to E-C; B-F goes inward to C-E.) So Ionian mode provided a new sense of drama:

"Wow look out, a monster tritone!"

"Phew here comes a major triad to make it all right"!

(and they all lived happily ever after )

 

That sense of dramatic narrative suited the culture of European imperialism and the industrial revolution, as well as the post-classical Romantic era. It was good to have music that illustrated the concept of confronting dark, unruly nature and mastering it (taming and exploiting it) to produce sweetness and light.

(You can extend the metaphor- if you like - to the symphony concert culture, where you have an orchestra (trained workers, soldiers or monks) governed by a conductor (manager, captain or priest) performing the works of a composer (inventor, explorer, or God). And all witnessed and approved by the masses in polite reverence in concert halls.)

 

It should be no surprise, of course, that that whole culture began to break down around the beginning of the 20th century, when the major-minor key system began to run out of steam (all its dramatic tensions had been exploited to the point of over-familiarity), at the same time as the assumptions of secure political hierarchies began to falter.

The 20th century was marked by increasing democratisation of culture, helped by media technology. Music in particular was profoundly changed by audio recording. Now you didn't have to go and witness real musicians performing live (and pay whatever that cost).

African-American music - the music of what writer Christopher Small called the "African diaspora" * - was extremely well suited to this fluid opening up of mass culture. It was democratic - of the people, by the people, for the people - and based around dancing and improvisation. In its inner "conversations" with the composition and among the musicians (and in responses to and fro with an audience), it represented a kind of ideal democratic society; in contrast to the celebration of authoritarianism, of rigid "know-your-place-ask-no-questions" hierarchy that the symphony concert had seemed to come to represent.

(Of course, composers like Beethoven never intended their music to become that; nobody really controlled the process; it was just a natural response to social forces at the time. IOW, there were no "powers that be" controlling it now. It was musicians and composers leading the developments, although naturally they responded to the wishes and moods of their patrons and audiences.)

* http://books.google.co.uk/books/about/Music_of_the_Common_Tongue.html?id=nE-RCSajBCMC&redir_esc=y

 

Similarly, the old certainties of the major-minor key system began to give way to various alternative organisational principles. Schoenberg et al tried doing away with key altogether, making all 12 equal tempered notes equivalent. Debussy, Ravel, Bartok and others rediscovered medieval modes, as well as national folk music cultures, and explored scales like the wholetone and non-functional quartal harmonies. Stravinsky tried things like polytonality (two keys at the same time).

Very few of these experiments resonated successfully with the mass audience, which was still fond of the familiar old key system (ever tried singing along to Schoenberg, or whistling a Stravinsky riff? or dancing to Stockhausen? ). Popular music hung on to keys well into the new century. Jazz (not surprisingly) led the way into new areas in the late 1950s, when Miles Davis got bored with the frantic roller-coaster of functional bebop sequences, and was inspired by African music and old gospel tunes to look for something cooler and more meditative, based around just one chord. Pianist Bill Evans (who knew about Debussy) brought his knowledge of modes and quartal harmony, and "modal jazz" was born.

 

Rock - because it sprang from blues and R&B - had always had modal instincts in its blood (blues is at heart a one-chord modal music). It always distrusted those too-neat "perfect cadences" of conventional major and minor keys, and much preferred funky b7s to cute leading tones. So - knowing nothing of the theory or history - it easily found its way to mixolydian and dorian, scales with Celtic folk ancestry as well as African blues associations.

 

 

Er, where were we....? Wake up at the back there!

 

[cont below... maybe grab a coffee first....]

[JonR]

Sultans uses the classic "Andalusian cadence" (common in flamenco): Dm-C-Bb-A. (A major, not Am .) what is the common Andalusian cadence? I haven't heard of it! hehe

http://en.wikipedia.org/wiki/Andalusian_cadence

[Cary Chilton]

Nice write up on the history!

 

So the minor progression of HC used modal interchange for the purpose of voice leading?

Can the Natural minor use modal interchange in the same way as a Major Key?

 

BTW, Jon in Sweet Child the solo:

( Em C B7 Am Em C B7 Am ) x2

( Em G A C D Em G A C D ) x2

 

 

Is is modulation to Natural minor or still in D mixo? BTW, B7??? V/V/V/V?

What is your analysis?

 

 

 

Since posting I have learned TWO great ACDC have mixolydian progs! BACK IN BLACK E mixo and SHOOT TO THRILL A mixo which now explains why there wasn't a D# and G#, respectively.

 

 

 

 

I forgot to use a fundmental question: Why the hell do our ears accept chords from parallel modes? I mean, first of the root is not the same and second the borrowed chords do not contain the same notes of the parent key. I mean, what it is preventing us composers from total anarchy.... chromatic harmony wherever / whenever?

[Jasco]

 

I want to ask what is the best way to approach modal progressions. That is, a chord progression with the distinctive sound of a particular mode.

 

 

JonR may have already answered this... I didn't take time to read all his good knowledge here.

 

But... my simple answer would be to start with one chord vamps.

 

And try to incorporate or emphasize the 'character note' in each mode. That is what gives each mode it's flavor. Both in your vamp and your improvisations.

 

To my ear, the "character note" of each mode is:

 

Ionian: 7

 

Dorian: 6

 

Phrygian: b2

 

Lydian: #4

 

Mixolydian: b7

 

Aeolian: b3 or b6

 

Locrian: b5

 

 

You may hear it differently???

[polishpaul]

 

....what it is preventing us composers from total anarchy....

 

 

Nothing.

 

Welcome back Cary!

[Cary Chilton]

 

Welcome back Cary!

ha! thnx

 

 

Jasco, right on, I hear that, too. Dorian, not sure if I'd pick 6?

[Cary Chilton]

Jon?

[Cary Chilton]

bump!!!!!!!!!!

 

 

Nice write up on the history! So the minor progression of HC used modal interchange for the purpose of voice leading? Can the Natural minor use modal interchange in the same way as a Major Key? BTW, Jon in Sweet Child the solo: ( Em C B7 Am Em C B7 Am ) x2 ( Em G A C D Em G A C D ) x2 Is is modulation to Natural minor or still in D mixo? BTW, B7??? V/V/V/V? What is your analysis? Since posting I have learned TWO great ACDC have mixolydian progs! BACK IN BLACK E mixo and SHOOT TO THRILL A mixo which now explains why there wasn't a D# and G#, respectively. I forgot to use a fundmental question: Why the hell do our ears accept chords from parallel modes? I mean, first of the root is not the same and second the borrowed chords do not contain the same notes of the parent key. I mean, what it is preventing us composers from total anarchy.... chromatic harmony wherever / whenever?

 

[JonR]

Since posting I have learned TWO great ACDC have mixolydian progs! BACK IN BLACK E mixo and SHOOT TO THRILL A mixo which now explains why there wasn't a D# and G#, respectively.

Yep - a couple of totally conventional "rock mixolydian" tracks.

 

I should say that the frequency of mixolydian mode in rock is as much down to how easy the chords are in key of E! (This explains why E mixolydian - and to a slightly lesser extent A mixolydian - is a lot more common than other mixolydian modes.)

All guitarists know E, D, G, A and C open chords. All beginners have trouble with F and B.

"The key of E major sounds great because we have that nice low bass keynote. But dammit there's supposed to be a B chord! the hell with it, D sounds just fine let's use that!"

Same with all those chords "borrowed from the parallel minor" - G, C and Am. They're part of every guitarist's basic repertoire. So if you're writing in the key of E (and you don't give a hoot about theory), you're going to experiment with adding all the easy chords you know. So, pretty quickly, you're going to hit on the "parallel minor borrowing" concept without having any idea what it is, or that it is a "concept" at all.

 

[cont below... once again your questions have provoked a response exceeding forum limits! must try and control myself...]

[JonR]

 

and second the borrowed chords do not contain the same notes of the parent key. I mean, what it is preventing us composers from total anarchy.... chromatic harmony wherever / whenever?

Nothing! As John Cage said, music is "organised sound". He meant that any (and every sound) could be employed in music (not just tuned pitched notes), but the important word is "organised". We have to perceive some kind of organisation in the music - otherwise it really is just noise.

 

As I mentioned above, Schoenberg worked on constructing music in which all 12 notes were equivalent - abandoning "key" entirely. But he had to apply some very rigorous rules in order to prevent any note assuming a key role. Our ears will look for that, automatically (partly because of cultural conditioning), and if any note seems to emerge as more frequent than another, we'll latch on to it, and start to try to hear it as a keynote. So he invented "tone rows" in which all 12 notes were used once before any of them could be repeated.

 

The interesting thing is that - although he was influential on a lot of later composers - his music can't be said to have caught the public imagination. It was too "difficult". 12-tone music - of course - has other organisational principles which one has to listen for, in place of the familiar old idea of key. But that's too much like hard work for most audiences.

 

In jazz, they tried something similar with "free jazz", but that didn't quite catch on either (except as a refreshing way of clearing the decks). What did work was a more subtle assault on the idea of key, the merely partial demolition job (and restructuring) represented by "modal jazz".

Modal jazz was often about stringing chords together that did NOT share a key (or a root note). It was like you moved from one key (mode) to another, apparently at random, usually without any warning or preparation. (In old jazz, modulations were common, but usually according to familiar rules, and usually well prepared beforehand.) And once you were in that new "key", well, you didn't go anywhere, you just hung on one chord.

The idea was to resist the idea of movement through a progression that characterised "functional" (key-based) harmony. (For the same reason, they frequently also avoided chords built in 3rds, building them in 4ths instead, which were much more ambiguous.)

Quite often, however, modal jazz DID adhere to "modal interchange" rules. So you have a series of chords that were quite unconnected, except they all had the same bass note.

And because the old key progressions weren't totally abandoned (just opened up and reconfigured), post-modal jazz remained quite accessible.

[Cary Chilton]

Hey Jon~ I thought you vanished. Slash, AC/DC probably didn't know a lot of this theory! hehe I will need to re-study HC, it was been a long time since I played it. I can better review what you saying when I re-learned and study it.

 

Any thoughts why Sweet Child would have modulated up to the Key of Em for the solo from D Mixolydian?

 

In pop and Rock, if modulating to a different Key for the bridge, or heighten chorus or solo, it is most accepted to modulate a whole tone above from the Keys Root?

 

 

What I meant by my modal interchange question was: If a song is in E major, and it borrows em from the parallel, due to the fact that the same rootnote ( and as you pointed out the 5th supporting the root). Logically, this makes perfect sense to me.

 

 

I ii iii IV V vi vii

D MAJOR: D . Em . F#m G . A . Bm . C#dim

borrowed chords: . bII II bIII . ivm bV vm bVI . bVII .

D LYDIAN: E(7)

D MIXOLYDIAN: Am C

D DORIAN: F (G7) Am C

D AEOLIAN: F Gm Am Bb C

D PHRYGIAN: Eb F Gm Am Bb Cm

D LOCRIAN: Eb F Gm Ab Bb Cm

 

My Question really is about how or why is it acceptable to use a Ab or Bb in Dmajor?

It certainly doesn't have the rootnote D and yet in Jazz we accept this deviation simply because it came from a mode or parallel minor, whose I chord shared the same note as the Key it was brought into??? G >GM A>AM not a big stretch same root, with a 5th to support it.

[JonR]

G >GM A>AM not a big stretch same root, with a 5th to support it.

Not following you now...

[Cary Chilton]

lol I meant it is not hard to accept using Gm chord if the Key has a Gmajor. Borrowing minor chords with same rootnotes that the parent key also has...via modal interchange.

 

It is the other chords available, the flatted chords,.... do share any tonality with the parent key?

[JonR]

 

lol I meant it is not hard to accept using Gm chord if the Key has a Gmajor. Borrowing minor chords with same rootnotes that the parent key also has...via modal interchange. It is the other chords available, the flatted chords,.... do share any tonality with the parent key?

Yes - if one accepts that "tonality" is a flexible concept.

http://en.wikipedia.org/wiki/Tonality

 

Defined broadly, "tonality" as I understand it can accept chords borrowed from parallel scales. The central point is that the sense of keynote remains. IOW, whatever chord(s) you add, the sense of D as the "tonal centre" must remain. It certainly does with the usual borrowings from minor used with a major tonic.

 

This is probably because we are almost as used to minor key music as we are to major key music, and while mixing the two (in parallel) obviously blurs the boundaries between the "majorness" or "minorness" of the key, it won't disturb the sense of the keynote, the tonal centre. IOW, whether we think we're in D major or D minor, we know we're still "in D", in some form: that's what matters. We have our tonal "anchor", and the rest is just some enjoyable shifting around that point.

 

Where it might arguably start to to get shaky is with borrowings from the more remote or exotic parallel scales: lydian, phrygian, locrian, or odd modes of harmonic or melodic minor (or ethnic scales) which don't normally have a tonic function. In any case, such surprising additions could easily be counterbalanced by returning the progression to more familiar chords.

[Cary Chilton]

I ii iii IV V vi vii

D MAJOR: D . Em . F#m G . A . Bm . C#dim

borrowed chords: . bII II bIII . ivm bV vm bVI . bVII .

D LYDIAN: E(7)

D MIXOLYDIAN: Am C

D DORIAN: F (G7) Am C

D AEOLIAN: F Gm Am Bb C

D PHRYGIAN: Eb F Gm Am Bb Cm

D LOCRIAN: Eb F Gm Ab Bb Cm

 

So using D major for simplicity: F#m the iii chord and notes F# A C

say the composer wants to use F Major from Dorian or Aeolian, F A C

 

The D Dorian shares the same keynote, however the chord in question is not a D chord, it is F borrowed from D Dorian. Are the A C notes enough to tell our ear that F is an allowable departure from F# - tonality intact? With other borrowed chords from e harmonic/melodic chords, is it also true that most of the chords will share at least two notes?

[JonR]

With other borrowed chords from e harmonic/melodic chords, is it also true that most of the chords will share at least two notes?

Not exactly. Speaking just of triads, the V chords share all 3 notes (it's the same chord!). The IV and iv chords each share two notes (root and 5th); the bVII and viidim share 2 notes (3rd and 5th); the others (iii & bIII, vi and bVI) share one note - the 3rd in each case.