[sdiy] Pitch shift in modulated BBD delays

[Gordonjcp]

On Tue, Jun 16, 2026 at 02:20:42PM +0100, Tom Wiltshire wrote:
> I've spent a long time wondering about how the LFO waveshape relates to the final pitch shift you get when modulating a BBD clock, as you would in a Chorus or Flanger circuit. Or even a delay-based analogue vibrato, come to that.
> 
> I recently managed to get some interactive demonstrations done, which I think make the whole thing a lot easier to understand. Here's the finished article. Perhaps some of you will find it interesting.
> 
> https://electricdruid.net/weird-wiggles-bbd-clock-modulation/ <https://electricdruid.net/weird-wiggles-bbd-clock-modulation/>
> 
> Any thoughts, comments, or error-spotting appreciated.
> 
> Thanks,
> Tom

So where does that actually happen? The chorus in the Juno 106 at least is modulated with a triangle wave at the same amplitude and one of two speeds, and gives a very distinct pitch shift - but that shift is dead steady, sharp/flat/sharp/flat deedaahdeedaah like a toy police car.

-- 
Gordonjcp