- Hi, and welcome to
this video in our series
of dealing with modulation.
So just so we're sure what
we mean by modulation,
this is when a piece of music's in one key
and we want to move to another key.
Well why would we want to bother?
Lots of people are very happy
making up a piece of music
in C major and just staying
in C major for the rest
of their lives but actually
it begins to be a bit tedious
after a while, particularly
the longer the piece
you're either writing or improvising.
So to be able to modulate,
move to another key,
is a really useful thing to be able to do.
So what I'm going to
talk about in this video
is how to deal with this, a
modulation by a semitone shift
because when composers
first got into dealing
with modulation in the
1600s and the 1700s,
they tended to modulate to nearby keys
and that carried on being
the case certainly during
the Classical period and
it was in the 19th century
where people began to be more adventurous.
So back in those earlier
days, you'd think, well I'm in
C major so maybe I could
modulate to G major
because that just involves adding a sharp,
or maybe I could modulate to F major
because that just involves
adding a flat from C major.
Or maybe I could go to the
relative minor key of A minor.
In other words, they
would modulate to keys
that were quite close by.
So what happens if you want
to do something more radical
than a closely related key,
but you want to go to a key
that's really quite a long way away?
And if you want to be
really sure about keys
you may be happy with that,
but if you're not have a look
at our video on the circle of fifths
that explains how the
whole key system works
and then you can see where
the closely related keys are
and where the keys are
that are further away.
So something that happens
in a lot of songs is that
you have the first verse,
and maybe the first chorus,
in one key and then maybe it's
going to shift up a semitone
just to give the whole
song a bit of a lift.
It would happen in a lot of
pop music, it might happen in
worship songs in church,
lots of different contexts
where you might want to do this.
And when some writers
decide to go up a semitone,
they do it without kind of transitioning,
in other words you finish in
one key and suddenly you launch
into another key a semitone higher,
and it's a bit like driving
a car and changing gear
without using the clutch,
you can kind of do it
but it doesn't do your gearbox much good
and there's certainly quite a jolt.
Now there's a way of smoothing
over this by a little trick
that I'm going to show you.
So say we're in the key of C major,
and maybe we're getting
to the end of a section
or the end of a verse
or a chorus or something
and we want to shift up a semitone.
Now when you think about it,
a semitone up from C major
takes us to D-flat major.
Now D-flat major's got five flats so it's
a long way away from C major.
So how do I do that,
because when I modulate
from one key to a neighbouring key,
I try to find something
called a pivot chord.
In other words if I'm going
from C major to G major
I can say that chord I in C major is also
chord IV in G major, so
that's a pivot chord.
II isn't a pivot chord because
it's got F natural in it.
III's a pivot chord,
IV's not because it's got F natural in it.
V's a good pivot chord
because V in C is I in G.
VI in C is II in the key of
G, VII's not a pivot chord.
So you see there are some
chords in common with
both the keys, so you
pass through a pivot chord
and then you carry on in the new key,
and it's a way of using
that kind of musical clutch
to go from one key to another smoothly.
But if you want to go
from a key like C major
with no sharps no flats,
to a key like D-flat major,
with five flats, it's quite
tricky to find a pivot chord,
isn't it?
But you can do this, find a pivot note.
And in this case we're
going to use the note C.
And what we do is we're
tiddling along in C major
quite happily.
Minding our own business in C.
And we're quite happily in C.
Now we want to go up a semitone.
So what do we do?
We take the tonic chord in C major,
we use the C as a sort of pivot note
and then under that C we
put the dominant seventh
of the key that's a semitone above.
So let's think about that,
a semitone above C major
is D-flat major, so I'm
talking about finishing
on chord I,
or the tonic chord in C major
and then using the dominant
seventh in D-flat major
which does have a C in it.
So I do this.
So you see what's happened?
That takes me to the
tonic chord of D-flat major.
So from there it's very easy to do this.
So you can see that this is the
tonic chord in D-flat major.
So you see how we've done this?
We've finished in C.
We've used a dominant seventh in D-flat,
and then we've gone on in D-flat major.
And can you see how I've just
managed to go into that key
which is five flats away and
it just goes very smoothly
because we've used this
dominant seventh in the new key.
The reason it works is
that the C is a pivot note
that connects the keys.
So you can do that from any key to any key
just simply by saying if
you're going up a semitone,
if that's what you want to
do, finish on the tonic chord
of the key you're in, find the
dominant seventh of the key
that's a semitone higher,
put that in, then put the
tonic chord of the new key,
and off you go in the new key.
So it's a nice little trick to know,
a modulation using a semitone shift.
