<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Yes, I did read <a href="https://sound-au.com/articles/muting.html">https://sound-au.com/articles/muting.html</a>. <div>Thanks. I think that transistor muting circuit is commonly used in commercial applications, and is okay as long as you can add your own buffer on the output. </div><div>No zero-crossing discussion necessary this time.</div><div><br></div><div>Benjamin <br><div><div><br><blockquote type="cite"><div>On May 8, 2025, at 10:18 AM, David Huss via Synth-diy <synth-diy@synth-diy.org> wrote:</div><br class="Apple-interchange-newline"><div><meta charset="UTF-8"><div style="margin-top: 0px; margin-bottom: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration: none;">The legendary website of Rod Eliott (ESP) provides a good overview as well:<br><a href="https://sound-au.com/articles/muting.html" class="moz-txt-link-freetext">https://sound-au.com/articles/muting.html</a></div><div style="margin-top: 0px; margin-bottom: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration: none;"><br></div><div class="moz-cite-prefix" style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration: none;">On 2025-05-08 15:12, Mike Bryant wrote:<br></div><blockquote type="cite" cite="mid:CWLP265MB713254F3DBA05199BB9D438BDB8BA@CWLP265MB7132.GBRP265.PROD.OUTLOOK.COM" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration: none;"><div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt;">Chapter 21 (well it was in edition 2) of Douglas Self's book on audio which should be on every audio engineer's shelf covers almost every way of muting a signal. One of those should suit you.</div><hr tabindex="-1" style="display: inline-block; width: 1290.65625px;"><div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size: 11pt;"><b>From:</b><span class="Apple-converted-space"> </span>Synth-diy<span class="Apple-converted-space"> </span><a class="moz-txt-link-rfc2396E" href="mailto:synth-diy-bounces@synth-diy.org"><synth-diy-bounces@synth-diy.org></a><span class="Apple-converted-space"> </span>on behalf of Benjamin Tremblay via Synth-diy<span class="Apple-converted-space"> </span><a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a><br><b>Sent:</b><span class="Apple-converted-space"> </span>08 May 2025 13:56<br><b>To:</b><span class="Apple-converted-space"> </span>synth-diy mailing list<span class="Apple-converted-space"> </span><a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a><br><b>Subject:</b><span class="Apple-converted-space"> </span>Re: [sdiy] Muting circuits for line out</font><div> </div></div><div><div dir="auto">The original design had the power switch on the volume knob. I suppose that was a way to mitigate this.<br id="x_x_lineBreakAtBeginningOfSignature"><div dir="ltr">Benjamin Tremblay</div><div dir="ltr"><br><blockquote type="cite">On May 8, 2025, at 8:44 AM, Benjamin Tremblay<span class="Apple-converted-space"> </span><a class="moz-txt-link-rfc2396E" href="mailto:btremblay@me.com"><btremblay@me.com></a><span class="Apple-converted-space"> </span>wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">Oh wait, I suppose the patent is for an fm signal that has not yet been demodulated.<br id="x_x_lineBreakAtBeginningOfSignature"><div dir="ltr">Benjamin Tremblay</div><div dir="ltr"><br><blockquote type="cite">On May 8, 2025, at 8:30 AM, Benjamin Tremblay<span class="Apple-converted-space"> </span><a class="moz-txt-link-rfc2396E" href="mailto:btremblay@me.com"><btremblay@me.com></a><span class="Apple-converted-space"> </span>wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div>Hello,</div><div>I have this lovely Univox JR-5 rhythm machine I have modded with knobs to control the sound mix. The original circuit was high gain but impedance sensitive so it summed current, not voltage and was very </div><div>I added a simple op amp to handle the mix. When power is turned on there is a horrible thump that sounds like it is 100x too loud. </div><div>I have been looking for a simple muting circuit. When I was repairing a Roland MC-909 I saw the muting circuit was little more than a pair of BJTs shorting the signal path. </div><div>I also saw this novel patent which attenuates the signal without much voltage offset, maybe?</div><div><div style="display: block;"><div class="x_x_apple-rich-link" role="link" style="display: inline-block;"><a class="x_x_lp-rich-link" rel="nofollow" href="https://patents.google.com/patent/US4288753A/en" dir="ltr" role="button" width="300" moz-do-not-send="true" style="border-radius: 10px; font-family: -apple-system, Helvetica, Arial, sans-serif; display: block; width: 300px; overflow: hidden; text-decoration: none;"><table class="x_x_lp-rich-link-emailBaseTable" cellpadding="0" cellspacing="0" border="0" width="300" style="table-layout: fixed; border-collapse: collapse; width: 300px; background-color: rgb(227, 227, 227); font-family: -apple-system, Helvetica, Arial, sans-serif;"><tbody><tr><td><table bgcolor="#E3E3E3" cellpadding="0" cellspacing="0" width="300" class="x_x_lp-rich-link-captionBar" style="table-layout: fixed; font-family: -apple-system, Helvetica, Arial, sans-serif; background-color: rgb(227, 227, 227);"><tbody><tr><td class="x_x_lp-rich-link-captionBar-textStackItem" style="padding: 8px 0px;"><div class="x_x_lp-rich-link-captionBar-textStack" style="max-width: 100%; margin: 0px 16px; overflow: hidden;"><div class="x_x_lp-rich-link-captionBar-textStack-topCaption-leading" style="overflow-wrap: break-word; font-weight: 500; font-size: 12px; overflow: hidden; text-overflow: ellipsis; text-align: left;"><a rel="nofollow" href="https://patents.google.com/patent/US4288753A/en" moz-do-not-send="true" style="text-decoration: none;"><font style="">US4288753A - Muting circuit with operational amplifier - Google Patents</font></a></div><div class="x_x_lp-rich-link-captionBar-textStack-bottomCaption-leading" style="overflow-wrap: break-word; font-weight: 400; font-size: 11px; overflow: hidden; text-overflow: ellipsis; text-align: left;"><a rel="nofollow" href="https://patents.google.com/patent/US4288753A/en" moz-do-not-send="true" style="text-decoration: none;"><font color="#A2A2A9" style="color: rgba(60, 60, 67, 0.6);">patents.google.com</font></a></div></div></td><td class="x_x_lp-rich-link-captionBar-rightIconItem" width="30" style="padding: 6px 12px 6px 0px;"><a rel="nofollow" href="https://patents.google.com/patent/US4288753A/en" moz-do-not-send="true"><div><favicon.ico></div></a></td></tr></tbody></table></td></tr></tbody></table></a></div></div><br></div><div>I really just need to prevent that initial thump. I’ll pick up a relay if that is best. </div><div><br></div><div>Is there an easier solid-state solution? I don’t mind adding another buffer stage at the output.</div><br id="x_x_lineBreakAtBeginningOfSignature"><div dir="ltr">Benjamin Tremblay</div></div></blockquote></div></blockquote></div><div class="x_BodyFragment"><font size="2"><span style="font-size: 11pt;"><div class="x_PlainText">________________________________________________________<br>This is the Synth-diy mailing list<br>Submit email to:<span class="Apple-converted-space"> </span><a class="moz-txt-link-abbreviated" href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a><br>View archive at:<span class="Apple-converted-space"> </span><a href="https://synth-diy.org/pipermail/synth-diy/" moz-do-not-send="true" class="moz-txt-link-freetext">https://synth-diy.org/pipermail/synth-diy/</a><br>Check your settings at:<span class="Apple-converted-space"> </span><a href="https://synth-diy.org/mailman/listinfo/synth-diy" moz-do-not-send="true" class="moz-txt-link-freetext">https://synth-diy.org/mailman/listinfo/synth-diy</a><br>Selling or trading? 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