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As audio ADCs don't like too low frequencies as they see it more as a wandering DC baseline, one often rolls off the bass anyway then lifts it back up in the digital domain. I know a few people don't like this technique but I don't think there's much actually
information one can lose in a 20Hz base note.<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Synth-diy <synth-diy-bounces@synth-diy.org> on behalf of René Schmitz <synth@schmitzbits.de><br>
<b>Sent:</b> 06 March 2024 14:02<br>
<b>To:</b> synth-diy@synth-diy.org <synth-diy@synth-diy.org><br>
<b>Subject:</b> Re: [sdiy] Free SSM2044, SSM2056 chips for pickup and one question about single supply VCAs</font>
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<div class="PlainText">Am 06.03.2024 um 01:31 schrieb brianw:<br>
> It's very common to use a single supply and handle all signals with a DC offset internal to the circuit. This just requires biasing the op-amps to "virtual ground" - which is half of the supply voltage (or somewhere around there).<br>
><br>
> I glanced at page 35 of that schematic, and the output op-amps on the right of the schematic have a series capacitor. This series capacitor will remove the DC output and present an AC signal beyond that point. The waveforms are probably all biased with a
center around 6V instead of 0V.<br>
><br>
> The drawback of this approach - besides requiring a lot more capacitors on the inputs (if any) and outputs - is that the frequency response is not flat all the way down to 0 Hz. It's usually not even flat down to 20 Hz, which we can hear. However, since nearly
all "affordable" electronics do this, we're not really complaining about the sound.<br>
<br>
The speaker cabinet in these organs problably doesn't go to 20Hz either.<br>
<br>
It is not difficult to dimension caps such that the bass loss is avoided.<br>
<br>
But one shouldn't make them too big either, as this can lead to problems <br>
in recovering from certain overdrive situations.<br>
<br>
<br>
Best,<br>
<br>
René<br>
<br>
-- <br>
<br>
synth@schmitzbits.de<br>
<a href="http://schmitzbits.de">http://schmitzbits.de</a><br>
<br>
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