Help with time signatures.
I'm sorry dwswift, my english is not perfect and so perhaps i kinda mess the things up in writing what i had in mind. What i meant is this...
Let's imagine i'm playing to a metronome.... if i'm in 12/8 (12 cand be divided per 3) i can divide each beat of the metronome in three equal parts. This means that each beat has the value of three eight notes. If i'm in 4/4 i can divide each beat in two... this meaning that every beat has the value of two eighth notes. Basically time signature can be divide in two great folders.
The first is simple signatures (4/8, 3/4, 4/4 ecc.) in other words all the signatures where you usually divide the beat per 2 (4/4= II II II II, 3/4= II II II). And composite signature (12/8, 9/8, 6/16) where you usually divide beat per 3 (12/8= III III III III, 9/8 = III III III).
Now let's take complex time signatures like 5/8 or 7/8.
Here you can't divide every beat per the same number.
Let's imagine we are playing with a metronome.... every beat has the value of two eighth notes. We are in 7/8 . So first beat..II, second beat... II, third beat.... II now we can't play two notes in the last beat otherwise we'd play in 8/8. So we can't play this to a metronome because the last beat should be shorter... the half of the previous ones exactly. Now one can ask.... why don't we set the metronome so that every beat is a eighth note and simply count 1234567 eighth notes?
In fact you can do this when the whole piece is in the same time signature. But if the signature changes and the tempo is not VERY slow this won't be very pratical. Imagine fo example we have 2/4.... we'll set the metronome with a beat= a quarter note..... then, some bars later in the same piece, we encounter 5/8. When we get to the complex time signature the metronome will only make a mess, since we can't divide every beat in the same way, like i've already explained before.
But we know that the eight notes have the same value (last for the same time) *in the two time signatures (unless it's otherwise indicated in the sheet of music).
So we must keep to have in mind the eighth notes, with the difference that in 2/4 we'd arrange them II II, while in 5/8 we'll arrange them either III II or II III. In fact the 5/8 bar is longer than the 2/4 (always supposing that it's indicated that the eighth notes have the same value in the two signatures) because we have five eighth notes instead of four, and so the metronome will be pretty much useless in this case.
A good example for this is Dream Theater's "Learning to live" :read:. At a certain point we have an alternation between 12/8 and 11/8. We can play with a metronome the first bar but not the latter, unless we don't set the metronome to a beat=a eighth note...... but that won't be very useful because we'll have to set it at 288 bpm!:shocked:
So we'll keep counting eighth notes in our mind and we'll divide the first bar III III III III and the second one III III III II.
It will be VERY simpler to explain if i had a way to write in musical notation.....
Well... i hope i wrote it down in a comprehensible way!