[sdiy] Techniques for Multiplying MIDI Clock frequency?

Benjamin Tremblay btremblay at me.com
Sun Dec 19 16:00:26 CET 2021


Thanks to all for the responses, I apologize for hijacking the thread.

> On Dec 19, 2021, at 6:50 AM, Adam Inglis (synthDIY) <synthdiy at adambaby.com> wrote:
> 
> 
> 
>> On 19 Dec 2021, at 20:47, Gordonjcp <gordonjcp at gjcp.net <mailto:gordonjcp at gjcp.net>> wrote:
>> 
>> So I guess the MPC60 must use some sort of software PLL to evenly double up the incoming clock pulses to get 48ppcn clocks.  The Roland W30 has something like 192ppcn and also responds to external MIDI clock, so it must do some very clever measurement - or, perhaps, when you get that fine you don't really notice a bit of wibbly-wobbly clocking.
> 
> 
> I’ve not used a W30, but I understand it’s sequencer runs the standard Roland “Super MRC” software that runs on the MC-300, MC-500 and MC-50 midi sequencers, and that runs at 96ppqn, not 192.
> Also swing or shuffle aren’t actually even mentioned in the manual, and there is no specific setting for this, you have to do a little trick with the quantize function.
> Another problem is that various companies don’t stick to a standard when it comes to using the “percent” terminology.
> Roger Linn explains it thus:
> 
> "My implementation of swing has always been very simple: I merely delay the second 16th note within each 8th note. In other words, I delay all the even-numbered 16th notes within the beat (2, 4, 6, 8, etc.) In my products I describe the swing amount in terms of the ratio of time duration between the first and second 16th notes within each 8th note. For example, 50% is no swing, meaning that both 16th notes within each 8th note are given equal timing. And 66% means perfect triplet swing, meaning that the first 16th note of each pair gets 2/3 of the time, and the second 16th note gets 1/3, so the second 16th note falls on a perfect 8th note triplet."
> 
> but Cubase has another method altogether!!
> 
> Gordon you said 67% sounds “lumpy”… but that’s just triplets! It shouldn’t sound lumpy… unless not everyone is in sync!
> 
> I take a look at some of this stuff here
> https://mezzoauto.blogspot.com/2017/08/swing-conversion.html <https://mezzoauto.blogspot.com/2017/08/swing-conversion.html>
> 
> WRT to Spiros original enquiry, I don’t understand why you need to drastically change your clock PPQN numbers in order to experiment with polymeter rhythms… but then, I’m not using modular gear. 
> What you definitely do need is rock solid clocking at whatever your chosen resolution, so that any subtleties like the push and pull of swing aren’t lost in the jitter.
> 
> A
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