"
BPM is not BPM" - or: "
What the hell is wrong with my song?"
[PROBLEM]
I was trying to synchronize a music keyboard with a drum sequencer using MIDI clock. The keyboard was using its arpeggiator feature, claiming the tempo for it to be 120 BPM. Fine. So I just set the MIDI clock in my recording software to 120 BPM, but then the drums were too slow. They were exactly in-time, but simply too slow. Now what the hell...?
I thought: "a-haa! no problem. I'll just double the clockspeed for the drums, because it's gotta be faster, and it can't be anything in between...".
I was wrong. 240 simply was too fast.
[SOLUTION]
In the end I figured out that it makes sense in a musical way to have the arpeggiator running at 120, but playing a 160 BPM beat to it. Since those two speeds have a common divisor, the timing is ok.
It's kind of hard for me to clearly visualize that problem in my head, but I've heard it and so I know it's a fact.
If I understood it correctly, it looks somewhat like this: ('o' is the end of the rhythm)
Code: Select all
------------------c---b--------a
a 120 x x x o x x x
b 160 x x x o x x x o x x
c 240 x x x o x x x o x x x o x
[PROBLEM #2]
Unfortunately this is easy to solve for recording purposes, but it poses an ugly problem for live scenarios: Synchronizing several devices using MIDI clock, but some of them need different BPMs??
-ouch-
[SOLUTION #2]
I've written my own cheap MIDI clock using pd, so it think it's possible to generate 2 different BPM signals based on the same "metro"-object.
[PROBLEM #3]
(...it never ends....

)
Each clock needs its own MIDI device (since the clock is channel independent). soooo? how to fix that?
[SOLUTION #3]
For some setups (and mine, too I hope) there are workarounds using MIDI loopback devices, since the drum sequencer is software and only the Triton LE (keyboard) is connected by cable.
Actually, I think the arpeggiator pattern should be changed to make it cleanly work with the drum-tempo. From the drummer's point of view I'd say that all instruments should listen to the drum - and not the other way round, or with mixed BPMs
