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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b>From:</b> Synth-diy <synth-diy-bounces@synth-diy.org> <b>On Behalf Of </b>Florian Anwander<br><b>Sent:</b> Thursday, December 5, 2019 11:13 AM<br><b>To:</b> synth-diy@synth-diy.org<br><b>Subject:</b> Re: [sdiy] Enveloppe follower<o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><p>Hi Jean<o:p></o:p></p><div><p class=MsoNormal>Am 04.12.19 um 17:31 schrieb Jean Bender:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><pre>discovered that most of them was pretty good for following musical<o:p></o:p></pre><pre>instruments signals, but not so much for more electronic audio<o:p></o:p></pre><pre>signal..<o:p></o:p></pre><pre>I mean, i play a lot of ambient and noise stuff, including sounds<o:p></o:p></pre><pre>without so much attack, even if they have some relief.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>And that's my point : i'd like to build myself an enveloppe follower<o:p></o:p></pre><pre>able to be really subtle, and able to be effective even on droning<o:p></o:p></pre><pre>sounds...<o:p></o:p></pre><pre>So where should i take a look ? What i have to be careful of ?<o:p></o:p></pre></blockquote><p>Brian wrote all the theory already.<o:p></o:p></p><p>Your main problem is: drones typically don't have a significant change in amplitude. On the other side: drones often change the colour of sound, the spectrum.<o:p></o:p></p><p>So I think you don't need a simple envelope-Follower, but you might need something more complex. I could imagine something like the analysis section of a vocoder, with an circuit after it, that outputs a voltage that corresponds to the frequency range or frequency weight.<o:p></o:p></p><p>I did not think it completely over, but a first attempt might look like this:<o:p></o:p></p><p>A state-variable-filter splits the signal in two signals: high and low. Both signals then are fed through an envelope follower each. Now the output voltages of the two env-followers are subtracted. The result would be something like:<o:p></o:p></p><ul type=disc><li class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1'>full frequency-spectrum = 0V<o:p></o:p></li><li class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1'>only high frequencies = +maxV<o:p></o:p></li><li class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1'>only low frequencies = -maxV<o:p></o:p></li></ul><p>I am not sure, whether the result is really interesting or usable, but it might be worth a try.<o:p></o:p></p><p><o:p> </o:p></p><p>Florian<o:p></o:p></p><p><o:p> </o:p></p><p>I think Florian has a great point regarding spectrum versus loudness. <o:p></o:p></p><p> I wonder (brainstorming) if something akin to a “color organ” would be interesting here, too? Divide the input into 3-4 frequency bands and provide an envelope follower on each. <o:p></o:p></p><p>Then you could mix / match use each output in a different manner?<o:p></o:p></p><p>Dave<o:p></o:p></p></div></body></html>