<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 16 Jun 2026, at 21:21, Gordonjcp <<a href="mailto:gordonjcp@gjcp.net" class="">gordonjcp@gjcp.net</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">On Tue, Jun 16, 2026 at 02:20:42PM +0100, Tom Wiltshire wrote:<br class=""><blockquote type="cite" class="">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.<br class=""><br class="">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.<br class=""><br class=""><a href="https://electricdruid.net/weird-wiggles-bbd-clock-modulation/" class="">https://electricdruid.net/weird-wiggles-bbd-clock-modulation/</a> <<a href="https://electricdruid.net/weird-wiggles-bbd-clock-modulation/" class="">https://electricdruid.net/weird-wiggles-bbd-clock-modulation/</a>><br class=""><br class="">Any thoughts, comments, or error-spotting appreciated.<br class=""><br class="">Thanks,<br class="">Tom<br class=""></blockquote><br class="">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.</div></div></blockquote><br class=""></div><div>I'm not entirely sure what you're asking. "Where does that happen?"...Where does <i class="">what</i> happen?! It happens in the circuit, right?!</div><div><br class=""></div><div>If I'm interpreting you correctly, I think that if you play with the sim, setting the LFO waveform to triangle, and the delay stages to something short (is it 256 or 512 in the Juno? I don't remember without looking it up) and most importantly set the modulation type to "Linear Period", you'll see a "deedahdeedah" pitch shift. It seems a lot like realising modulation of the clock <i class="">period</i> rather than the <i class="">frequency</i> was what gave Roland the edge in the chorus world. Given that, increasing the clock frequency/shortening the delay reduces the pitch shift. Lowering the clock frequency/lengthening the delay increases the pitch shift. Changing the LFO Frequency or Depth also has an effect. The sim shows the differences.</div><div><br class=""></div><div><a href="https://electricdruid.net/modulated-bbd-delay-simulation/" class="">https://electricdruid.net/modulated-bbd-delay-simulation/</a></div><div><br class=""></div><div>T.</div></body></html>