<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style>
</head>
<body dir="ltr">
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);" class="elementToProof">
Since what the OP probably wants is 2<span><sup>nd</sup> harmonic, you can use a pair of comparators on opposite polarities feeding into a summing op-amp, low pass filtering the output, then adding this into
</span>the original signal at a lower level with another op-amp. A 2901 quad op-amp will add to the vintage-ness of it
<span id="🙂">🙂</span><br>
</div>
<div id="appendonsend"></div>
<hr style="display:inline-block;width:98%" tabindex="-1">
<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 Tom Wiltshire <tom@electricdruid.net><br>
<b>Sent:</b> 04 April 2023 10:12<br>
<b>To:</b> Chris McDowell <declareupdate@gmail.com><br>
<b>Cc:</b> synth-diy@synth-diy.org <synth-diy@synth-diy.org><br>
<b>Subject:</b> Re: [sdiy] what opamp for "warmth"? (I know, I know...)</font>
<div> </div>
</div>
<div class="BodyFragment"><font size="2"><span style="font-size:11pt;">
<div class="PlainText">Yeah, I was going to suggest an OTA too. I suppose a differential pair might be another option (basically the input curve from an OTA).<br>
<br>
The LM13700 is one of the few chips that I would say actually has "a sound", and that sound is definitely vintage.<br>
<br>
Tom<br>
<br>
<br>
> On 3 Apr 2023, at 22:34, Chris McDowell via Synth-diy <synth-diy@synth-diy.org> wrote:<br>
> <br>
> You could use an OTA like the LM13700. They're pretty noisy and clip softly! Will certainly "old up" your sound some.
<br>
> <br>
> Chris McDowell<br>
> <br>
>> On Apr 3, 2023, at 4:18 PM, Neil Harper via Synth-diy <synth-diy@synth-diy.org> wrote:<br>
>> <br>
>> i know this is going to be controversial, and I'm grabbing my popcorn..<br>
>> <br>
>> i have a digital effect that I'd like to "warm up" in the last dry/wet mixing and output buffering stage. So wondering if there's any choice of opamp that might give some favorable non-linearity quality to the output sound. Would be running them with a single
supply +9V.<br>
>> <br>
>> as for what specs constitute "warmth", I'll leave that up to you.. :)<br>
>> <br>
>> <br>
>> <br>
>> -- <br>
>> /// Neil Harper<br>
>> /// Every Wave is New Until it Breaks<br>
>> _______________________________________________<br>
>> Synth-diy mailing list<br>
>> Synth-diy@synth-diy.org<br>
>> <a href="http://synth-diy.org/mailman/listinfo/synth-diy">http://synth-diy.org/mailman/listinfo/synth-diy</a><br>
>> Selling or trading? Use marketplace@synth-diy.org<br>
> <br>
> <br>
> _______________________________________________<br>
> Synth-diy mailing list<br>
> Synth-diy@synth-diy.org<br>
> <a href="http://synth-diy.org/mailman/listinfo/synth-diy">http://synth-diy.org/mailman/listinfo/synth-diy</a><br>
> Selling or trading? Use marketplace@synth-diy.org<br>
<br>
<br>
_______________________________________________<br>
Synth-diy mailing list<br>
Synth-diy@synth-diy.org<br>
<a href="http://synth-diy.org/mailman/listinfo/synth-diy">http://synth-diy.org/mailman/listinfo/synth-diy</a><br>
Selling or trading? Use marketplace@synth-diy.org<br>
</div>
</span></font></div>
</body>
</html>