[sdiy] Analysis of the TB-303 CPU timing

rsdio at audiobanshee.com rsdio at audiobanshee.com
Sun Mar 19 10:55:23 CET 2017


On Mar 16, 2017, at 1:47 PM, Richie Burnett <rburnett at richieburnett.co.uk> wrote:
> I couldn't hear any difference there, but that's quite a slow leisurely pattern.  You're more likely to hear a given amount of ms of jitter on a faster pattern, so try a pattern with loads of repeating 16th notes at a frantic tempo with generous use of accents and slides.  That might be more revealing.  (Also use higher pitched notes to reveal timing detail, because it's easier to perceive onset timing for notes with higher fundamental frequencies.)

I think you need to give some values in Hertz to clarify "higher pitched" notes.

For binaural sound localization, frequencies below 80 Hz are difficult or impossible to localize because the phase difference between the ears is too small. Above 80 Hz and up to 800 Hz, the human brain can use time delays to localize sound, based on the inter aural time delay of 625 microseconds. Above 1.6 kHz, the dimensions of the head are greater than the length of the sound waves, so it's not possible to localize based on phase. This is where level differences come into play for localizing sound.

Of course, all of that is dealing with really small time delays for sensing the direction that a sound is coming from, assuming that the same sound wave hits both ears. I don't know how that relates to general perception of timing, but it seems like super-high frequencies might also present difficulties. Timing of transitions from silence to note triggers might have no upper limit on frequency. I'm just curious whether you have any suggested frequency ranges.

Brian





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