[sdiy] Techniques for Multiplying MIDI Clock frequency?

Brian Willoughby brianw at audiobanshee.com
Sat Dec 18 22:05:01 CET 2021

```It's more likely that the receiver *averages* the periods between the last 12 in order to set the period for its 16th-note timer. This assumes that 32nd notes are not allowed.

If those 48 PPQ blips are not equally spaced, then they will cause the average period to rise and fall even though it should be constant.

Brian

On Dec 18, 2021, at 12:56, Benjamin Tremblay <btremblay at me.com> wrote:
> I’m assuming all it does is divide by 12 to get a 16th note.
>
> Benjamin Tremblay
>
> On Dec 18, 2021, at 3:53 PM, Pete Hartman <pete.hartman at gmail.com> wrote:
>> On Sat, Dec 18, 2021 at 2:15 PM Benjamin Tremblay via Synth-diy <synth-diy at synth-diy.org> wrote:
>>> 2) I wish I understood the theory of clock multipliers. I have seen code that measures the period between clock pulses and dead reckons the double-time pulse as an average of the recent periods. But why? Why can’t I just fire another extra HIGH-LOW pulse whenever I get a MIDI clock event? Why does timing of the extra ticks matter?  I’m assuming 48 PPQ divides the clock down to individual sequencer steps on the KPR-77. As long as the divided clock is coming in on the beat, what does it matter if some of the synthetic pulses are a little off? (They’re just shadows of the main tempo clock). It’s not like the KPR-77 is inferring something or trying to calculate BPM from the external clock… So… Anyway I just wish I knew what I was aiming for, and then maybe I could hit the target.
>>
>> One suspects that most people are trying to write a general purpose converter.  E.g. you could run those 48ppq out to some other module, like an analog sequencer, and it would keep time.  I'm not familiar with the KPR-77, but I'm also slightly puzzled by the idea that some piece of gear would require 48PPQN but not care about the timing of half of the pulses.
>>
>> Pete

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