Chord theory epic: functional harmony, secondary dominants, substitutions and diminished 7ths

hey guys it's Bill Hilton here once again and today I've got something for those of you who are really into music theory I know there are loads of you out there because I get lots and lots of comments and questions on my piano tutorials about theory about how chords work about about kind of how Music Works under the hood you know loads of you are kind of really interested in getting in there and tinkering around with your own chord progressions maybe you're interested in production or songwriting you want to know how this how some of this stuff kind of sticks together so where this all comes from is that a couple of weeks ago I put out a piano tutorial called blues and jazz piano gamified yeah people seem to like it and in response some of you came along with these questions about the way the cor progression from that tutorial worked which I'm going to try to answer now don't worry if you haven't seen that tutorial yet yeah you might have done but if you if you haven't it doesn't matter because I'm going to go through the chords again if you would like to watch it after you've watched this tutorial then I'll include a link in the description field underneath this video you might need to click on the little um the little down arrow to to to reveal the description if you're watching on mobile I'll also stick a link in a YouTube card yeah that you can access by clicking the little I at the top right hand corner of the screen up there so here's the core progression that we're going to be working off and if you saw that previous tutorial you you you know you'll find it familiar but let's just have a quick refresher and a quick explanation of what's going on here for for those of you who haven't seen it before it's 16 bars long and it's in the key of C major with four beats in the bar maybe two beats in the bar if we played it quickly let me just play it through for you yeah with the chord symbols in subtitles so you can follow along I'll take this quite quickly so don't worry about kind of um you know having to slow it down and copy what I'm doing because what I'm most interested in doing here is giving you a sense of the sound of the progression here we go we've got c c diminish 7 D Minor 7 G7 e- 7 A- 7 dor 7 d flat major 7 C E7 a minor 7 E flat diminish 7 C over G D7 D- 7 G7 C G7 kind of a turnaround bar to take us uh to take us back to the start you know that that was quite quick it wasn't strictly in time just a couple of things to notice again if you didn't see the previous tutorial in bars 13 and 14 there with those bars are split between two chords so we've got C over G on two beats D7 on two beats D minus 7 on two beats G7 on two beats and then we're back to regular 4 beat bars now the questions I've been asked and that have been about dozen of them so far or all kind of around the same topic given that I basically invented this chord progression for the purposes of the tutorial how did I come up with some of those chords like D7 and d flat major 7 and E7 and C diminished 7 that don't appear naturally in the key of C that don't incl that include notes that are not in the scale of C did I just make them up did I pick them at random in short where do those kind of weird chords like C diminish 7 come from let's start off by taking that kind of broad question and putting it in context now if you know a bit about music theory you'll know that the most common chords in any progression are those based on the scale of the key the progression is in so we're in the key of C major and here's the scale of C major all the white notes from C to C now the chords that we can if you like grow out of that scale the naturally occurring chords in C major C Major's dionic chords to give them their proper name R C D Minor E minor f g a minor and be diminished as you can see what I'm doing there is just playing a basic a very basic chord shape a Triad shape and moving it up the scale using nothing but the notes of the scale to generate those chords I could do it in any major key not just C so we could go into E flat major with lots of black notes there's the scale of E flat major and here I go generating the dionic chords the kind of native chords of that key in the key of E flat major just by running that simple Triad up the scale back to C we can also number those chords and and that's really handy because it means we can discuss them independent of key because Keys often change so the chord built on the first degree of the scale is the number one chord which we sometimes call the tonic then we have the number two then the number three chord the number four chord the number five chord really important we call the number five the dominant chord the number six chord and the number seven chord and then at the octave we're back to the number one chord the tonic absolutely key Point here within a song in C major you'd expect to find those chords the dionic chords of C more often than any others in fact it's likely that nearly all and in many songs absolutely all of the chords in a song's chord progression will be taken from that list of dionic chords or there'll be extensions of those dionic chords like D Minor 7 instead of D minor or G7 instead of G or whatever all of the dionic chords of a key have what we call a function yeah so what we're talking about here is functional Harmony a chord function is basically the job it tends to do in a chord progression the role it plays in making the progression work so for example the function of the chord built on the fifth degree of the scale that's G in C major is what we call a dominant function I I just said we could we call that number five called the dominant chord its job is that it naturally takes us back to a chord that has a tonic function which is most often the tonic chord c okay the chord built on the first note of the scale so um in turn we would say that the function of that chord is tonic it's a chord that kind of sounds like home so dominant tonic dominant tonic I'm playing them in inversions there to make it clearer but they're still basically the same chord the job of the dominant chord is to want to take us back to the tonic chord and the job of the tonic chord is to be to be home the place where the music sounds at rest where there's no tension okay so the job of the dominant chord it's function to use the technical terminology is to resolve to the tonic I don't want to dig too far into functional Harmony because not to put too fine of points on it yet it can get madly complicated and there are various different approaches and ideas when it comes to expressing the roles of the the different chords but very roughly just to use one of the ways of describing the roles of chords of those seven chords built off the major scale there are broadly three types of function yeah some chords have a tonic function that's the tonic chord itself yeah and sometimes the number three chord E minor in the key of C major and sometimes the number six chord a minor in the key of C major some of the chords have a dominant function we've seen that the number five chord the dominant chord g in C major yeah that has a dominant function we even call it the dominant chord but um there's also this B diminished chord the number seven chord um yeah and um that also has a dominant function those two are often combined there's G there's B diminished yeah to give us the chord of of uh give us a dominant seventh chord G7 in the key of C major okay which has an even stronger resolve back to the tonic okay so the job of dominant chords the function of dominant type chords is to lead us back to Tonic type chords most often the tonic chord c but not always yeah whether it goes to any any other kind of tonic chord or you know to C or E minor or a minor that would drag us into talking about cadences which are really useful and and really interesting as a theory topic but I don't kind of want to get stuck in there just yet then as well as tonic and dominant type Tye chords there's the third and final type which are predominant or subdominant chords yeah those are chords that tend naturally to lead to a dominant chord and those are the number two and the number four chords D minor and F in C major and sometimes the number six chord a minor and C major can do that job as well let's think about how all of that sticks together any core progression is a journey out and back and it usually starts on a tonic type chord and goes out to a dominant chord and comes back again not always but that you know that's the kind of the standard model from home out to the furthest point of tension and Back Again tension release so a really simple progression will go tonic say the one chord out to dominant the five chord and back again to the number one chord again I'm playing those chords in different inversions but they're still cgc tonic dominant tonic more complex progressions would use the tonic okay and then a subdominant or predominant call it what you like like D Minor then a dominant chord and then back to the tonic okay now most progressions of most songs even quite simple ones will be built of several tonic dominant tonic or tonic subdominant dominant tonic however you know several of those Journeys yeah you you've probably heard of things like 2 5 1 sequence quencies that often get used at the end of chord progressions a number two chord to a number five chord to a number one chord really common in jazz and lots of popular music that's basically a subdominant dominant tonic sequence of chords two 5 1 D minor G C subdominant dominant tonic needless to say and this is always the case in music theory the rules so-called rules get bent and broken all the time by everyone from you know Beethoven to Farrell Williams yeah and that's because they're not really rules at all if when you're thinking about core progressions you're in a kind of rules-based mindset then you need to kind of get out of that way of thinking harmonic Theory doesn't say to you you must do this and if you don't it's definitely wrong rather it says this is what tends to work so what the the rules tell us is that if you're wri a chord progression then you know if you use the dionic chords of the key that you've chosen and if you go tonic dominant tonic or tonic subdominant dominant tonic then that will always sound at least kind of okay and logical but and here we come back to our question it's not the only thing we can do so if we know that the dionic chords of our Key C major in this case all have their kind of different functions all have their particular roles they can play the jobs they can do in our progression then where do we get those chords that don't apparently belong in the key these non-diatonic chords as we call them that use notes from outside the key where do they come from what are their functions yeah did I did I just make them up so the first thing to understand is that no I didn't I didn't just add them at random I didn't just make them up these cords do have particular ular jobs to do let's start off as an example with this E7 chord that we have here in B 10 now E7 isn't a chord that's dionic to the key of C major because it contains this G sharp and you won't find a g Shar in the c major scale what this E7 is in fact is what we call a secondary dominant okay it's a chord that's the number five chord the dominant chord actually it's a dominant seventh chord of the chord that follows it you which will usually be a chord dionic to the key we're in the way you spot secondary dominance usually is by looking at the chord that comes after them so if you look at the next chord in the progression you'll see that it's a minor 7 which is dionic it's naturally occurring in the key of C it only uses notes on the c major scale it's a number six chord in um in C major now E7 as we've said isn't dionic to the key of C but it does act as a dominant to this A minor chord and resolves to it very n very naturally and very nicely so from the c major chord in bar 9 we have this sudden and dramatic jump out out of key if you like to E7 but it resolves very quickly back to a chord that is in the key A Minor 7 yeah because it acts as as I say a dominant to that chord it's a secondary dominant in the key of C major as with many non-diatonic cords we can think of um a secondary dominant that jump to E7 as as a shortlived and very unstable key change that as soon as it's happened what wants to resolve back to the home key yeah it's it's like one of these if you're a physicist it's like a fundamental particle that only exists for a tiny moment before you know settling back into equ equilibrium we have another secondary dominant in the second half of bar 13 in the form of this D7 chord now D7 isn't dionic to C major because it has an F sharp in it and there's no F in the scale of C major so as I said usually the process we go through to identify as a secondary dominant is to look at the next chord okay but whoops there's something a bit complicated going on here because under ordinary circumstances would expect this D7 to resolve to a G chord because it's the five chord of G Okay g is the five chord of C okay so we call it we call that D7 the five of the five of C C to use a technical terminology but here instead of going to G or at least directly to G it moves briefly to D Minor 7 before finally reaching the G so is it a secondary dominant or not tricky but yeah it probably is we can probably say it has that function because it sets up the expectation of going straight to a G chord even though it doesn't actually go straight there yeah you could see that transition from the D7 to the D Minor 7 as a weird kind of deceptive Cadence to use a technical term or you could see the D Minor 7 G7 combination in Bar 14 as a substitution for a straight 4B G7 chord yeah because in fact D Minor 7 with a a g in the base is a common substitution for G7 in the key of C okay or if you lik you could just see it in terms of chromaticism a little harmonic color especially since we transition from a D7 to a D Minor 7 really only involves that single semmit tone that single half step shift from F to F natural an interesting side point here is that even a relatively way out dominant 7th like that E7 in the key of C can actually find its way back to the tonic by a very straightforward route although that isn't what's happening in this progression but what we could do is resolve E7 to a a A7 to D D7 to G and G7 back to C the tonic and what we're doing there is making use of the circle of fifths this endless chain of fifths all resolving down onto each other until you get where you want to go yeah you you know we could go even further out than um than E7 we could go out to a a flat 7 okay and we would go a flat 7 d flat 7 to g flat 7 to B7 to E7 to A7 to D7 to G7 to C okay you know you you can go that far out and come back again using the circle of fifths not many progressions use a string of fifths that long many just kind of use a segment of of that cycle to get where they want to go but it's a useful thing to know about okay so as chords in jazz and Blue's progressions go secondary dominance pretty standard pretty ordinary let's have a look at something a bit more exotic now here in bar eight we've got this d flat major 7 chord and that definitely isn't dionic to see because we've got a d flat and an a flat in there neither of those notes in the c major scale so why is it there what is it doing what is its function now when we see a chord like that that's so apparently out of place but doesn't seem to be a secondary dominant one of the things we have to wonder is if it's some kind of substitution usually a complex cord that's been dropped in instead of something more straightforward but which has the same harmonic function as a more straightforward chord so is this d ma d flat major 7 a substitution in the key of C well maybe now if this were a more plain vanilla kind of core progression then the chord we might expect to see in that bar is G7 okay because we've had the D minus 7 subdominant then would expect to go to G7 dominant and back to the tonic chord in the next bar Yeah so basically if this is a substitution it's substituting a dominant chord now this d flat major um d flat major seven chord that we we've got here looks a bit like one of the most common of all dominant substitutions which would be a trone substitution that would be the chord of d flat 7 substituting for G7 now the trone substitution is a dominant seventh chord built on the Note a trone that's three whole tones three hold steps a sharp and fourth above the root notes of the original dominant seventh chord so here's G7 and a trone up from the root is d flat and from that we build d flat 7 and it kind of has this uh kind of exotic sound really common to the point of being a cliche in jazz but it works as a dominant chord yeah it resolves up to the tonic the reason it does that is that it has these two notes the F and the B strictly speaking a C flat and a D7 chord but d flat uh d flat 7 chord but we'll call it a b it has those two notes in common with G7 yeah and this B is a really important one because in the home key of C it's the leading tone the note right below the tonic C and that leading tone really really really wants to drag us up to the tonic yeah in the same way the F kind of wants to go down to the E so that can work from a G7 chord or from a d flat 7 chord okay trone substitution it's just that the trone substitution is a bit more exotic sounding so we could say that this d flat major 7 is just a slight variant by one semmit tone on the trone substitution it's a bit less strong a bit less pronounced but it has a similar kind of of effect more generally we could see it as an altered chord we could see it as the D Minor 7 that's just been altered to give it a little bit more harmonic color and the D minus 7 the subdominant chord you know just resolves straight to the you know you know the the tonic chord that comes next which subdominant chords can and often do do although you know it's a subtler Cadence it's a subtler resolve than the dominant tonic now in Broad music theory terms an alter chord is a dionic IC chord like D Minor 7 that has had one or more of its notes raised or lowered by a semitone or half step there's some scope for confusion here because in jazz Theory the term altered is usually used to describe chords built from a scale called the alter dominant scale and that isn't quite what's going on here although it's close yeah if it were straight top trone substitution that would be the case because the trione substitution is built off the alter dominant chord but we're getting kind of deep into Jazz jungle there you know so so let let's not go further but you could describe it as a kind of altered chord as well now when I was composing the progression and this is a point worth making about composition in general I didn't actually have either of those views in mind I didn't say to myself hm you know I've got D Minor 7 and I want a a kind of dominant chord next I know let's have a tritto substitution and alter it a bit I just kind of let my fingers do the thinking and thought hey you know that sounds cool I'll I'll keep it yeah very few songwriters in particular or in fact improvisers go into what they're doing with this very kind of theory oriented kind of left brain approach oh you know I've done this so now I need one of these and and and that will fit and blah blah and so on you just improvise it and think yeah that sounds nice and then the theory explains it afterwards so that d flat major 7 if you like kind of an alternate subdominant chord that's a bit like a trione substitution and maybe has a kind of dominant function yeah the main thing is that it sounds cool finally what's the deal with these diminished seventh chords we have a c diminished 7th in bar two and then an E flat diminished 7th in bar 12 what are they doing what's their function what's their role in the chord progression so the first thing to understand here is that the diminished seventh chord is a four note chord made up of a root note with three minor thirs stacked on top of it and there are basically only three of them that's because and this is a good trick if you can do it C diminish 7th uses the same notes as E flat diminish 7th and F Shar diminish 7th and a diminish 7th and then C Shar diminish 7th is the same as e diminish 7th and G diminish 7th and B flat diminish 7th and D diminish 7th is the same as F diminish 7th and a flat diminish 7th and B diminish 7th and that's it we covered all the notes of the octave with just three chords building a diminish sth off each of them so this C diminish 7th chord is basically the same chord as the E flat diminish 7th just in a different inversion no full diminished sth chord as opposed to half diminished sth which are a bit different I'm not going to talk about here no full diminished sth chord is dionic to any major key if you use a full diminished seventh chord in a major key it will always use at least one note that is not in the scale of that key you're always jumping out of key to some extent so what do these crazy diminished 7ths do I was skimming through the Wikipedia article on diminished 7th just before I sat down to make this tutorial and it says there and I quote music theorists have struggled over the centuries to explain the meaning and function of diminished sth chord and I was like well yeah you know you can say that again although it's really unclear the best way to think of them is in the context of major Keys is as points of instability now a regular dominant seventh chord a dominant chord is also a point of instability but it has a clear resolution a clear route back to stability to the tonic and if it takes any other route yeah if it resolves anywhere else which it can do it can do that but it's always kind of doing that in defiance of what your air expect a diminish seventh chord on the other hand like see diminish sth here can resolve to a few different places now the most widely accepted resolution in traditional music theory is that it resolves upwards to the major chord built on the Note a semitone above the root of the diminished seventh chord which acts as you know because that root kind of acts as a leading tone and that from C diminish 7th would take us to d flat and you can hear that's kind of a that's kind of a fairly natural resolution but in terms of the progression we're looking at we'd be heading off in totally the wrong direction yeah it will also resolve pretty nicely to F or F major 7 or to a minor and also to D Minor 7 yeah which is actually where we go in bar three after the C diminish 7 you can even go off to A7 and woo you know down into the circle of fifths well hey off we go as we said a diminished seventh chord is always a point of instability but in bar two it resolves to that D Minor 7 chord in bar 3 and in bar 12 the E flat diminish s um resolves to the C over a g in bar 13 and in each of those cases it's a pretty successful resolution and it's happening pretty much on the basis of common tones of shared notes with each of those chords so um the C diminish 7 shares a c and an a with D Minor 7 yeah and the uh the E flat diminish 7 in bar 13 shares the C with the c chord that follows it so that all still kind of leaves the question what do these diminished seventh chords do what's the point of them why are they that why are they there what's their function the simple answer is that in terms of functional Harmony in terms of the structure of the core progression they don't do anything sometimes diminished sevs can have functions usually a kind of dominant function but here they're what we call you know this C diminish 7 this E flat diminish 7 are what we call nonfunctional chords or passing chords or color cords or if we want to be really fancy we might say that they're apuras decorations to the cords that go immediately before them yeah there's kind of a lot of different views of of the way diminish sevs work in the first three bars we could progress from that c chord to the D Minor 7 without the C diminish 7 in the middle all it's really doing is adding color so its job its function if you like is really just to kind of sit there and say pretty yeah as with the D um d flat major 7 my fingers just kind of found it when I was putting the progression together and I thought yeah that sounds cool and once again it was a creative process you know if you want to think in those terms I kind of write brain process and then after my fingers have found after i' improvised the cord and thought yeah that sounds nice that adds a little bit of interesting Jazzy color then we can think then I was kind of thinking about it in theoretical terms afterwards well that all got kind of technical is it yeah I I don't dive into heavy music theory that often but I know that those of you out there who are into it so I hope you found that useful and I hope it didn't kind of fry your brains too much as usual don't forget to subscribe to my channel if you haven't already maybe support me on patreon the links below and check out my book had really play the piano again there's a link below and also in a card up there on the top right just click the little ey button any questions or comments you happen to have stick them in the thread below and I'll do my best to answer you know Al you know this Theory stuff does get kind of mindboggling kind of Rocket sciency kind of quickly if you try to explain it in writing rather than at the keyboard anyway there we go new piano tutorials coming up in the next week or so I'm going to go I'm going to go and lie down after explaining all that I'll see you very soon

Channel: Bill Hilton

Views: 268,755

Keywords: chord theory, music theory, harmonic theory, harmony theory, functional harmony, chord functions, secondary dominants, diminished seventh, chord substitution, chord progressions, non-diatonic chords, jazz chords, blues chords, jazz chord progression, how chords work, how music works

Id: AYBQUvmhAX8

Length: 28min 51sec (1731 seconds)

Published: Mon Jul 31 2017