Forum to discuss all matters relating to the MPC1000 and MPC2500 operating systems created by 'JJ' (all versions).
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By tsutek Sun Apr 06, 2014 3:25 pm
Hi,

I don't know if this has been discussed before, but I just found out that the timing of MIDI sequences on my MPC, while running any JJOS is quite jittery. I only found this out recently, if I try to make just a 16thnote hihat pattern at tempos above 160BPM, I get lots of jitter in the MIDI timing. Internal sample playback seems to be more stable tho.

Just tested and the same MIDI jitter does not occur on the original Akai OS.

Has anyone experienced the same? Is there something wrong with my settings perhaps?
By 313 studio tricks Sun Apr 06, 2014 6:41 pm
are you soloing the midi track when you measure its performance? presumably you would commit a midi line to sample when you were ready to and then use the superior internal timing or simply stick to creating your composition using internal sound and sync your external equipment.

my logic tends towards 'its economical and compact'. jjos and the 1000 is a great combo if you ask me.
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By m:t:c Sun Apr 06, 2014 7:04 pm
I doubt that midi jitter can be removed for good. By my experiments you'll always have +/- 5ms jitter if doing midi clock synced recordings. MTC with 1bar count-in has always been on point for me.
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By tsutek Mon Apr 07, 2014 7:48 am
There were no 16th hihat MIDI notes inyour example video AFAIK, Amen chops were occurring at most on the 8ths, but not a constant 16th note midi note repeat action. I can make a utube clips if necessary in order to demonstrate the problem..

I don't use MIDI sync, just MIDI notes. So you're saying it's not my settings? Bummer if so :(
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By le rat Mon Apr 07, 2014 10:36 am
I did a test few years ago. No 16th notes, just a simple click at the beginning of each bar to check the sequencer drift during approximately 11 minutes.

Akai OS was the tightest, OS1 or OS2 the worst and OS2XL average. I guess that it's because AKAI OS has less features that it's tighter in general.

Personnaly I can live with it and I don't think it's a setting problem. Probably only a matter of OS being pushed till its limits.
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By tsutek Mon Apr 07, 2014 11:09 am
Yeah, I mean it doesn't render the MPC unusable, but it does make it tough to make for example footwork via a MIDI controlled drumbox (tried two different ones so far, same jitter with both) without a midiclock syncable sequencer.

Think imma sell mine and get a 4000 since I have lusted for one of those for a year now anyway. The 2500 with JJOS is still a very nice machine for low/midtempo stuff, which is why I didn't find about this until now.

Or maybe Ill keep both ;)
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By m:t:c Mon Apr 07, 2014 11:37 am
One should conduct a test with os3/128xl. Tsutek, it would be appreciated if you have the time and energy to do a vid showing how much jitter you get. Sure you're not having a midi loop going on or weird cc-data recorded from those boxes? Is it just midi-out mpc -> midi-in drumboxes -> audio out -> mixer/audio interface ?
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By SimonInAustralia Mon Apr 07, 2014 11:56 am
m:t:c wrote:Sure you're not having a midi loop going on or weird cc-data recorded from those boxes? Is it just midi-out mpc -> midi-in drumboxes -> audio out -> mixer/audio interface ?

...and no MIDI clock or timecode being sent out the same MPC MIDI output as the MIDI note on/offs?

Have you plugged the MIDI output of the MPC into a computer, and checked the MPC MIDI output with a MIDI monitor application/utility, to make sure it is only MIDI note on/offs being sent out of the MPC MIDI output?
Last edited by SimonInAustralia on Mon Apr 07, 2014 12:48 pm, edited 1 time in total.
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By tsutek Mon Apr 07, 2014 12:44 pm
Thanks for the suggestions! Will make sure that no extra data is being sent. All the MIDI outs on my MPC go straight to MIDI ins on the tonegens, which are not sending anything out or thru.

I think I remember checking that MIDI clocks were disabled on the output ports as well but will triple-check.
By elmacaco Mon Apr 07, 2014 5:34 pm
Man, Boylan makes footwork on a 1000 with JJ OS IIRC, and Rashad and Spinn rock any and all MPCs, although not JJ OS yet.

footwork is pretty quantized so the slight jitter wouldn't matter but I don't hear any.

Might be polyphony on stereo samples messing with your tight sequences, make the sounds mono in all senses and see.
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By tsutek Tue Apr 08, 2014 7:44 am
Not saying that there's any problems with the internal sample playback, the internal sample triggering timing is OK, this only affects MIDI out notes.

Tried slaving the MPCs clock to a DAW last night, and the MIDI timing issue was gone, although I think I was using the stock Akai OS. Will try again with JJOS next, if having slaved to an ext clock solves my probs then I'll just get a MIDIpal or smthng and always slave to clock.