In trying to understand another 'Why?' I have one more question regarding time signatures:
In simple time it is said that the beats can be divided into two equal beats so, in 2/4 each crotchet can be divided into 2 quavers still keeping the vlaue of two crotchet beats per bar.
But in 3/4, there are three beats per bar (crotchets) how do these 'divide' into two equal beats? I can see that each crotchet can divide into two quavers as before, this time keeping the three beats, but the same can also be said of each quaver in 6/8 compound. Each quaver divides equally into two semi quavers.
Why then do we say they divide into threes? I know the sub division of beats sounds 123 223 so the two beats are grouped in threes (2x3 =6) when written.
I can't feel a sub division in 3/4 which would divide into two beats either?

In 2/4 and 3/4 the beats are crotchets so each crotchet divides into 2 equal quavers. In compound time each beat is dotted eg 6/8 is 2 dotted crotchets in a bar and each dotted crotchet dives into 3 quavers.

Sorry - am in a hurry. Will explain this a bit better later!

Not at all! Thank-you!

3/4 cannot be thoght of as two equal beats, its three ! Split into quavers........ 1 2 2 2 3 2
You end up with a compound 6/8 if you try to split it into 2....... 1 2 3 2 2 3

You're welcome!

Ahh right. So, is it classed as simple time because it uses a crotchet as a whole beat? I thought all simple time split into two equal beats ... Sorry if i sound dim i am a theory beginner ( goodness knows how I got to a practical G4 without understanding these simple things)



Just realised! crotchet still divides into two quavers! Sorry.

And if you go to smaller note values the crotchets can also consist of 4 semiquavers (or a combination that adds up to a crotchet.
In the same way your dotted crotchet in 6/8 9/8 etc. can be made up of quavers, semiquavers (or smaller) or any combination that adds up to a dotted crotchet.

no, no, no, no, no no, no, No, NO!!!!

It is classed as simple time because the unit of the main beats can be constructed from two smaller notes. In 3/4 the unit happens to be a crotchet. It could just as easily be 3/2 (unit minim, comprises two crotchets) or 3/8 (unit quaver, comprises two semiquavers) etc.

In compound time the unit of the main beats is built up from three smaller notes. So 6/8 (unit dotted crotchet, splits into 3 quavers) 9/16 (unit dotted quaver, splits into 3 semiquavers), 6/4 (unit dotted minim, splits into 3 crotchets)


I can think of a couple of reasons:

Maybe the concepts really are quite simple, as you say, but the notation we use is a bit stupid. It is reasonably consistent for the tiny subset of metric patterns that it evolved to represent but it is very limited - so it is incapable of expressing many basic patterns of metre and rhythm. For example a time signature cannot show the pattern of a Calypso rhythm (123 456 78) - so you write 4/4 then show the rhythm as two dotted crotchets followed by a crotchet, and/or by the grouping of quavers: two groups of 3 and a group of 2. Nor can it accurately show where the accents are to fall in a jazzy 5/4 - is it 123 45 123 45 or 12 345 12 345 or 12345 12345 ??

The main reason for finding it difficult is that time signatures are horribly badly explained in most "elementary texts". They start by telling you a misleading semi-truth (bottom number is type of beat, top number is number of beats - true for simple time only). Then get themselves into a mess when they get onto the subject of compound time. Hence confusion such as yours - that could have been avoided by telling the proper story in the first place.

So don't fret. Just accept the conventions. If the top number is any multiple of 3 bigger than 3 itself (in practice that means if it is 6,9 or, rarely, 12) then it is compound time, and the unit is some sort of dotted note. If the top number is 2,3 or 4 it is simple time. As for other top numbers, the conventional system of time signatures was established when composers tended not to use metres like 5/4 and 7/4, so it has no special terms for them, does not handle them especially well, and can't show the rhythmic pattern that is intended by them.