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<p>Hi Jean<br>
</p>
<div class="moz-cite-prefix">Am 04.12.19 um 17:31 schrieb Jean
Bender:<br>
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<blockquote type="cite"
cite="mid:CA+rzoo6+N+s8khWJSnYMZ9pB-6VDtBqo=CqpyFp=5ozwVEb2VA@mail.gmail.com">
<pre class="moz-quote-pre" wrap="">discovered that most of them was pretty good for following musical
instruments signals, but not so much for more electronic audio
signal..
I mean, i play a lot of ambient and noise stuff, including sounds
without so much attack, even if they have some relief.
And that's my point : i'd like to build myself an enveloppe follower
able to be really subtle, and able to be effective even on droning
sounds...
So where should i take a look ? What i have to be careful of ?</pre>
</blockquote>
<p>Brian wrote all the theory already.</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.</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.</p>
<p><br>
</p>
<p>I did not think it completely over, but a first attempt might
look like this:</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:</p>
<ul>
<li>full frequency-spectrum = 0V</li>
<li>only high frequencies = +maxV</li>
<li>only low frequencies = -maxV</li>
</ul>
<p>I am not sure, whether the result is really interesting or
usable, but it might be worth a try.</p>
<p><br>
</p>
<p>Florian<br>
</p>
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