How long does 1 bar last in 2/2 time at 120 bpm?
At 120 bpm, each beat should be 0.5 seconds. And there are two beats per bar, so I'd assume each bar would be 1 second. Am I misunderstanding something?
The software I'm using Logic Pro X, if I set my time signature to 2/2 and bpm to 120, 1 bar lasts 2 seconds.
Why am I so confused?
You are correct and Logic is wrong if looking at beat in the traditional way.
Logic and most other DAWs will always assume the quarter note gets the beat no matter what the time signature is so it will see 4 total beats in 2/2. From a music notation perspective the time signature dictates the beat and in 2/2 the half note gets the beat and there are 2 beats.
The conflict is due to the DAWs being more geared towards general music creation rather than music performance where this matters much more. To simplify this, by default the quarter note gets the beat as more or less the common user will write in 4/4 or not really care about what the time signature is.
I suspect that the bpm you specify is in crotchets (quarter notes) per second.
In 2/2, you have two minims (half notes) per bar. Hence, you also have four crotchets a bar (obviously).
If the 'beat' in beats per minute was minims, then each bar would take a second, as you expected. If it's really crotchets per second, then every bar will take two seconds.
Using crotchets is technically wrong, as you would expect the bpm in a 2/2 piece to be defined in terms of minims, not crotchets. But this sort of technicality may have been overlooked by the software developers.
There may be a way to correctly specify bpm as minims per second in Logic Pro, but I could not locate it via Google. The search was hardly comprehensive, however. Hopefully a comment will prove me wrong.
