Mario,

Way, way back in my early music-learning days, my piano teacher, Old Mrs Glover, was quite adamant that there were essentially two types of pulses that in music. These were "simple time" and "compound time". Simple times use complete notes for their pulses.

For example...
Simple Duple time (two counts in a bar) = 2/4 = 2 x 1/4 notes in a bar.
Simple Triple time (three counts in a bar) = 3/4 = 3 x 1/4 notes in a bar.
Simple Quadruple time (four counts in a bar) = 4/4 = 4 x 1/4 notes in a bar.

On the other hand, compound time signatures use dotted notes at the beat note.
Compound Duple time (two counts per bar) = 6/8 = 2 x dotted 1/4 notes in a bar (where 1 x dotted 1/note = 3 x 1/8 notes).
Compound Triple time (three counts per bar) = 9/8 = 3 x dotted 1/4 notes in a bar.
Compound Quadruple time (four counts per bar) = 12/8 = 4 x dotted 1/4 notes in a bar.

The thing with compound times signatures is that the top number of the time signature is always divisible by 3.

The 6/8, 2-counts-per-bar feel is very common with Irish folk tunes (Paddy's Leather Breeches in the original post) and Sousa Marches (such as the one below). The tempo of 136 is counting two pulses per bar where BIAB treats each pulse as a triplet of 1/8 notes. The tempo of 204, it counting 6/8 as equivalent to three pulses (in which case it would be better represented as 3/4 rather than 6/8).

One of Sousa's famous marches in 6/8. It's very easy to hear the left-right-left-right, 2-pulse rhythm.


From a BIAB perspective, whether these pulse beats are two groups of triplet 1/8 notes or two groups of 3 x 1/8 notes (i.e. a dotted 1/4 note), the tempo would always be 136 bpm because that's the speed of the pulses.

I don't know if this helps clarify things, but this is how I remember Mrs Glover's music lessons over 60 years ago.
--Noel

MY SONGS...
Audiophile BIAB 2025