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<div class="moz-cite-prefix">On 2025-08-04 08:11,
<a class="moz-txt-link-abbreviated" href="mailto:mskala@northcoastsynthesis.com">mskala@northcoastsynthesis.com</a> wrote:<br>
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cite="mid:alpine.LNX.2.20.2508040754270.7463@kharasan.bonobo-conspiracy.ca"><span
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I don't think there is really any phase reversal going on, because the op
amp (either version) can surely go at least as far as about -12V output,
at which point under the described circuit input conditions the op amp
inputs will still be within a couple of volts of zero, nowhere near the
point where they'd trigger phase reversal. I think the real issue is
clipping: the newer version can drive its output closer to the rails, and
so the circuit which depends on clipping behaviour, ends up clipping
differently.
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<p>Hi Matthew, thanks I always appreciate your detailed
explanations.</p>
<p>I've modified a PCB with the old TL074 so I can measure the
current between Q14 and the LM13700. The saturation (or as I call
it my intentional "squish") of the circuit is noticeable. With the
knob at 100%, the current is 32mA. If I add a 5V CV to
resonance-CV the current only goes up to 37mA.</p>
<p>With the new TL074H, the current drops immediately to 0mA as soon
as the resonance-CV goes over 1V with the knob at 100%. So I don't
think it's clipping, I think it's doing something entirely
different.</p>
<p>Mike</p>
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