[sdiy] Random trigger delay?

[Colin Fraser]

> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl 
> [mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of mark verbos
> Sent: 25 May 2002 12:54
> To: synth DIY
> Subject: Re: [sdiy] Random trigger delay?
> 
> The whole idea started with trying to imagine a box that could make 
> shuffle like a TR-909. In that case I think you have to split up the 
> 16th notes so that they alternate. first uneffected, then 
> delayed. For 
> that a trigger delay circuit would work.

909 shuffle is quite interesting. But you're going to have to do some
clock multiplication to get the right results.
The 909's timebase internally is 48 ppqn.
Even when synced from MIDI, the 909 can trigger notes exactly between 2
MIDI clocks, so it must be interpolating it's 48 ppqn clock from the 24
ppqn MIDI clock.

There are 7 different shuffle settings.
>From 1 to 7, these introduce a delay for even numbered steps of 0, 0.5,
1, 1.5, 2, 2.5 and 3 clock pulses assuming a 24 ppqn.
I got these results by analysing note timings in recordings of 909
patterns (all in 4/4 - different scales may use different values), with
the 909 running on internal then MIDI sync.
Results were identical in both cases.

The 909 flam uses increments of fixed delay, not related to tempo.
There are 8 settings for flam (on keys 9 to 16), equal to delays of 20,
20, 25, 30, 35, 40, 45 and 50 ms. Not sure why flam 9 and 10 are the
same. I double checked, but that seems to be correct.

Note that the 909 shuffle has twice the resolution of the 707/727
shuffle, which can only use delays of whole numbers of clock pulses.

Colin f