- Hi, in this video we're
going to think a little bit
about modulation.
We've got quite a few videos
out there on YouTube now
about modulation.
So what is modulation
just to be entirely sure,
it's when we start in one key
and then we move to another key.
There could be as many modulations
within a piece as a composer sees fit
or as an improviser decides to include.
Sometimes if you get so many modulations
it gets a bit chaotic.
But if you get stuck in one
key all the way through,
it starts to sound a bit boring.
So conventionally if you were a Baroque
or a Classical composer,
you would start in one key
and then you'd decide to
modulate to another key
that was close by.
So the most obvious
key that people went to
was the dominant key.
So if you started in C
major you might think,
"Okay I'll modulate to G major,
I've just added a sharp."
But you might go to the subdominant key
because that would take you
from C major to F major,
we just need to add one flat.
Or you might think, "I'm in C
major, I'd quite like to vary
"the tonality now so I'll go
to the relative minor key,
"which would be A minor."
But you see what they were
doing, they were going
to neighbouring keys on
the circle of fifths.
Well, by the time we get into
the 19th century particularly,
composers are wanting to
be a bit more adventurous
about this.
So they're trying to find ways of
going from one key to a key
that's quite a long way away
from where they've started.
Or they're moving quickly
through a series of keys.
So modulation starts to get
a little bit more exciting.
One of the chords that they start to use
is the diminished seventh.
The diminished seventh has been around
from the Baroque period onwards,
so it's not a new chord,
but it's been used
previously to have a
particular moment of drama,
particularly in the Opera,
if you wanted to paint a
word like pain or death
or sorrow.
Something like that.
But now in the 19th century
composers think, you know what
this diminished seventh chord
has got various options.
So let's start off by being sure
about what we mean by
diminished seventh chord.
Basically a diminished seventh
is a pile of minor thirds.
So if you give yourself a note like C,
you think what's a minor
third above it, E-flat.
What's a minor third above that?
G-flat you know or
F-sharp it doesn't matter
you could use the enharmonic
equivalent of minor thirds.
So it might be a minor
third or it might be
an augmented second, it doesn't matter.
But C, E-flat, G-flat
or C, D-sharp, F-sharp
another one on top, A, and as
soon as you've got four notes
that are each a minor third apart,
you have got a diminished seventh.
Okay so that's how it works.
If you want to key reference
a diminished seventh,
in other words, diminished
sevenths fundamentally
do belong to a key.
You build them on chord VII.
So if I'm in C major
and I look for chord VII
it's going to be B, D and F.
B to D minor third,
D to F minor third.
Stick another minor
third on the top of it,
hey presto, A-flat.
So, that's a diminished
seventh in the key of C.
So when you use it in a conventional way,
quite often the diminished
seventh will go to chord I.
It works in the major key
like this, that's C major,
it works just the same in C minor.
So, a conventional use
of the diminished seventh
would be to do something like that.
So if you're kind of working on a piece,
improvising, composing, whatever,
and you're kind of
tiddling along in C major,
but you're sort of thinking,
"Actually, my C major piece
is going quite nicely but
"it's not terribly full of colour."
You could think I'll have
a diminished seventh.
Ooh, a bit of drama you see,
and then carry on again.
So the diminished seventh
adds a little bit of colour.
Now if you want to modulate to other keys
of course there are
possibilities to look at this
diminished seventh and
to think about changing
one or more of the notes enharmonically.
So for example,
say I take the same diminished seventh,
and instead of thinking A-flat on the top,
I just think well actually,
I shouldn't really put the sharp sign
let's do this properly,
let's call it G-sharp.
All right, so I've got my G-sharp
on the top of the chord like that.
It's just the same chord
B, D, F, A-flat.
B, D, F, G-sharp,
but G-sharp sort of flags up
another possible key doesn't it.
Because I could go from
that one to A minor
or I could go from this one to A major.
I could even think, I
could use that to get to Ic
and then to V and
possibly to I in D minor.
Or I could do that with the
G-sharp and go to D major,
I and then maybe V-I in D major.
So do you see how one
enharmonic alteration
means that I can go to other keys.
So I'm in C major minding my
own business just tootling
along and C major you see,
not causing any offence to the world.
I could have a little
diminished seventh in C major,
just to have a little bit of colour.
Then I might think well
I'll go somewhere else
so I'll use that to
diminished seventh again
but this time I'm going to call it G-sharp
and then I could into A minor.
So that's worked quite nicely hasn't it,
taking me into A minor.
Or I could be in my C major
and then I could use
this diminished seventh
and then I could think
I'm going to D minor now.
You see, that's even more
interesting isn't it.
It's taking me a step further.
So you see how the diminished seventh
is a little bit flexible.
Or I could change another note of it
say I call the B at the bottom, C-flat.
Now where are we going with this?
So I've now got the
same diminished seventh,
sounds exactly the same,
but an enharmonic
alteration at the bottom.
So I'm now calling it
C-flat, D, F, A-flat.
Well what does that mean,
because if I've got C-flat,
that C-flat could fall to B-flat.
Isn't that a lovely sound.
C-flat to B-flat, and
then what have I got now?
I've got a dominant seventh
in the key of E-flat major
or in the key of E-flat minor.
Oh my goodness, so if you
wanted to do something quite
radical I could be in C major.
I could use this diminished
seventh that belongs to C major
but I could rename that B, C-flat.
And then I could end up in
E-flat major or E-flat minor.
So here I am again,
minding my own business in the C major.
Just enjoying listening to that.
I've had a little diminished
seventh in C major
to give me a little bit of colour.
Now I'm thinking, "You know what,
"this is getting a bit boring now."
So I'm going to use my diminished seventh
and I'm going to call
that C-flat at the bottom
and I'm going to go to E-flat minor,
do you see how I've done that?
And it floats straight into E-flat minor,
well isn't that amazing.
C major, no sharps no flats,
suddenly I'm in six flats.
So, diminished seventh
gives you some colour.
So quite a lot of the 19th
century composers realised that
the diminished seventh gave
us lots of possibilities.
I mean there are composers
around like Liszt
who kind of is a bit of a
diminished seventh king really.
I mean he writes pieces like this.
He's just using one diminished
seventh after another
just whizzing from one to the next
and it's kind of quite dramatic isn't it.
But composers also beginning
to see the possibilities
for doing this.
So it might just open up
some new possibilities
if you're wanting to modulate
in your improvisation
or in your composition, into another key,
think about whether the diminished
seventh is useful to you.
And whether you can use it
with some enharmonic alteration
to take you somewhere else.
Have fun with it.
