6/8 time signature - tempo calculation

If I understand correctly, all you need to do is drag a dotted 1/4 note symbol from the metronome indication box in the score section and it puts it in at dotted 1/4 note = 36

Is that what you want?

I just did it in Logic! You can see it here: http://www.flickr.com/photos/76366061@N00/4471683358/

Set tempo to 54 with a 6/8 signature, then dragged a dotted 1/4 note from the metronome indicator and it calculated 36.

Ah, I see... well I'm not entirely sure if I'm honest, though hopefully someone can clear this up.

Ordinarily, when writing in 6/8 you would always indicate the metronome in dotted 1/4 notes.

But despite setting Logics tempo at 54, this appears to be a 1/4 note tempo (not sure why?).

If it helps 36 comes from 54÷3=18, 18x2=36 (I also have a hunch it should actually be 72 though).

Anyway, all I'm doing now is making this more confusing, so hopefully someone with a better understanding of tempos/signatures can step in and clear this up.

Ko be wrote:
Hi,
I have a project in 6/8, the tempo is 54.

In Logic, this means that each crotchet =54bpm even though you are in 6/8.

Crotchet 54bpm = quaver 108bpm = dotted cotchet 36bpm (108/3=36)

This seems to be the case. I have several pieces in 4/2 or 3/2 & these all have the tempo given in crotchets in the Transport bar.

This STINKS. Since when are all values interpreted, read, tapped, understood, and experienced as CROTCH values????

This i a Bug which should have been fixed versions ago.

Ko be wrote:
Yes, but I would like to know what is the calculation I need to make in order to get that 36.

A quarter note, or two eighths, is 54bpm. You're looking for the bpm of a dotted quarter, or three eighths.

The ratio between what Logic offers and what you want is 2:3.

So you either divide by 2/3 or multiply by 2/3 to convert between them.

54 * 2/3 = 36

36 / 2/3 = 54

Since when are all values interpreted, read, tapped, understood, and experienced as CROTCH values????

I think the underlying reason for this has to do with the way midi works. A standard midi file can contain a set-tempo meta-event, which is used to communicate tempo information. The set-tempo meta-event defines tempo in terms of microseconds per quarter note (see here or here). This means that quarter notes are the basis for defining tempo, at least as far as standard midi files are concerned. So I think Logic does it this way because midi does it this way, and Logic wants to be compatible, with regard to importing and exporting standard midi files.

Logic does provide a way to see the 'correct' tempo in the Score, as siderealxxx pointed out above. This is explained (albeit superficially) in the manual ( pdf, pp. 886-7): "The tempo indicators in the Transport bar and the Tempo List always refer to quarter notes, even if a time signature with another denominator is used. As such, the displayed tempo differs, depending on the symbol being used."

Another interesting variation on this is LoopBack. I recorded a loop in 5/4 the other day. Loopback calculated the tempo as xxbpm in 4/4. The playback is definitely in 5/4.

That is interesting, and I didn't know. Thank you.

45 RPM,

Thank you for your explanation. I now understand. I don't like it, but I understand.

It might be nice if we had the option to "Show MIDI-file-compatible BPM," or "Show Toe-Taps BPM"

Only Victor Borge would (for comedy sake) tap his foot three times per measure in 6/8!!!

Perhaps the options should read: "For compound meters display tempo Victor Borge style,"

or "For compound meters display tempo the way every other human being in the know universe would interpret the word "BEAT" in the sentence in the term "Beats per minute."