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<div dir="ltr" data-setdir="false">(first time poster!)</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Hi Ian,</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Usually in my experience one would scale down resistors around an opamp to generally lower the johnson noise contribution. Additionally there is something to be said for high impedance nodes and coupling in radiated noise from external sources but usually that's only problematic over 1M. </div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(0, 0, 0); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">As to why it's commonplace, I'm not sure which schematics you are referring to, but as mentioned, 100k shows up a lot in eurorack circuits since it's the defacto input impedance.</span></span><br></div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">There are a ton of other factors in the decision of this resistor, it's hard to generalize rationale w/o the context of the circuit and design intentions. Happy to comment on something more specific.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Ben.</div><div><br></div>
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On Friday, November 13, 2020, 04:16:17 PM EST, Mattias Rickardsson <mr@analogue.org> wrote:
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<div><div id="yiv0322069605"><div><div><div><div class="yiv0322069605gmail_quote"><div class="yiv0322069605gmail_attr" dir="ltr">Mattias Rickardsson <<a rel="nofollow" shape="rect" ymailto="mailto:mr@analogue.org" target="_blank" href="mailto:mr@analogue.org">mr@analogue.org</a>> skrev:<br clear="none"></div><blockquote class="yiv0322069605gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div><div><div><br clear="none"></div><div>And perhaps 10k-22k for TL06x.</div></div></div></blockquote></div></div><div><br clear="none"></div><div>I should have written 22k-47k.</div><div class="yiv0322069605yqt8318435605" id="yiv0322069605yqtfd93142"><div><br clear="none"></div><div>/mr</div><div><br clear="none"></div><div><div class="yiv0322069605gmail_quote"><blockquote class="yiv0322069605gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div><div>
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