[sdiy] Question for those with musical ears

Tom Wiltshire tom at electricdruid.net
Thu Apr 15 21:01:38 CEST 2021


The VCDO chip I designed only manages 6 cent steps (16 steps a semitone, actually = 6.25). The chip also does a smooth glide from one note to another. In certain contexts you can hear the slight stepping, but the smooth glide isn’t really one of them. The movement seems to “blur” the steps, like your ear can’t keep up. As the movement gets slower, it’s easier to hear the steps, although still far from easy. One second per semitone is *very* slow for a practical glide, and on my chip would be possibly-perceptible. I usually scale things in "seconds per octave”, and the maximum on the chip was two or three seconds per octave. This is still slow enough to allow dramatic slow slides from one end of the keyboard to the other. A second per semitone to just crazy-slow, and only really serves a purpose experimentally, rather than musically.

Ultimately, no-one has ever complained about that aspect of my chip, so the vast majority of people can’t hear better than the Wikipedia-sourced “6 cents minimum perceptible difference”.

Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================



> On 15 Apr 2021, at 00:47, Mike Bryant <mbryant at futurehorizons.com> wrote:
> 
> Consider a continuous glissando played on an analogue synth - the frequency rises smoothly between the start and end pitches.
> 
> But on a digital synth there will always be discrete steps between successive frequencies as the frequency is gradually stepped between the start and end pitches.  
> 
> Question is, what is the minimum step (in cents) needed such that the best musical ears cannot tell the frequency isn't rising smoothly as on the analogue synth, but in many discrete steps.  
> 
> It may be that the rate of change can effect it so if so please assume a glissando starting at middle C rising at 1 second per semitone.
> 
> Thanks
> 
> Mike
> 
> 
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