Elektron Musical Instruments

Very cool report and graph, too. At which tempo was the MD for the test?

> known issues:
> 
> 1. MIDI over USB is purportedly not jitter-free.  there is no
> published spec for the MIDI interface's jitter that i know
> of, so it's something of an unknown quantity here

Not sure what you mean by jitter in this sense. FWIW the tolerance for 
midi timing depends on the sampling rate of the MIDI wire itself, which 
ends up being about 1%. That is, one device (the sender) can have an 
internal electrical timing that is about 1% off the other (the receiver) 
and you'll still be able to clearly tell what is coming in over the 
wire. (Online there seems to be a good deal of misundertanding about the 
baud rate for MIDI. IIRC it is 32 kilobaud and not 32,000 baud. Or maybe 
I got that backwards heh.) I guess maybe you're talking about things 
getting bumped over in little increments to suit the timing of USB? We 
could get all mathematical, but imho it can be considered negligible here.

> 2. the clock in MIDI monitor may not be consistent, either,
> but i hope it is.  at any rate, it times to the millisecond.

It's good that you used a Mac, because the resolution of the readily 
available timers in Windows suck. Something like 10ms resolution has 
been my experience. I don't remember if MIDI-OX or the like improve on 
that by using a timer that's deeper in the matrix; too lazy to check.

> 3. go and pour myself a beer.  samuel adams' imperial
> pilsner is surprisingly great, if you like really hoppy
> beers.

I'm gonna have to try that one. ChrisM, a member here on the list, 
turned me on to India pale ales and I especially like Pyramid's IPA when 
I'm in the mood for 'top of the hops'. Don't let him convince you to try 
"Golden Monkey", it will be your downfall.

> 797 ticks with 21ms between them
> 191 ticks with 22ms between them
> 13 ticks with 20 ms between them

Imho this is "good enough timing" and certainly better than alot of 
things I've seen. If you wanted to get really serious about seeing what 
the timing skew is, you could wire up a dedicated microprocessor with a 
UART module in it and log the exact times between those 0xF8 ticks 
(there are six of those per 16th-note) at a resolution much, much 
smaller than 1ms. Might be a righteous hack on a rainy day.

I think for the best timer, a manufacturer would want the MIDI ticks to 
be run by an on-chip timer that (highest-priority) interrupts everything 
in the instrument's CPU in order to get that 0xF8 sent off down the 
wire, and use a really tight crystal to drive the CPU's internal clock. 
The MD is really complex, so who knows how they are issuing clock 
messages, but I think your results show that it is performing at a 
professionally acceptable level.

In the words of Daniel Hansson, Elektron, "Dump on!"

,
Mark