<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">I don’t see any sonic advantages. If the offset voltage on the output of IC1B isn’t exactly 0 (set by R63) you will have audible clicks anyway.<div class=""><br class=""></div><div class="">As far as I can see from online images, the switch is not on the pcb. So it saves one wire to solder/assemble. Maybe it was just for economical reasons.<div class=""><br class=""></div><div class="">Ben</div><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 5 Oct 2020, at 16:25, ColinMuirDorward <<a href="mailto:colindorward@gmail.com" class="">colindorward@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="">Thanks Ben!</div><div class="">What's the advantage of doing this, rather than using a switch connected to the output buffer that toggles between either the processed or the unprocessed signal? <br class=""></div><div class="">Less click?</div><div class="">Colin<br class=""></div><div class=""><br class=""></div></div><br class=""><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Oct 5, 2020 at 12:43 AM Ben Stuyts <<a href="mailto:ben@stuyts.nl" class="">ben@stuyts.nl</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><div class=""><blockquote type="cite" class=""><div class="">On 5 Oct 2020, at 05:28, ColinMuirDorward <<a href="mailto:colindorward@gmail.com" target="_blank" class="">colindorward@gmail.com</a>> wrote:</div><br class=""><div class=""><div dir="ltr" class=""><div class=""><a href="http://www225.pair.com/audio/waltzingbear/Schematics/Urei/545.JPG" target="_blank" class="">Here</a> is the schematic for the Urei 545 PEQ. I understand that it's a highpass filter followed by four BP SVFs summed into the dry signal, then a lowpass filter.</div><div class="">I'm stuck on the in/out switch, though. What's going on here? I know what it's supposed to do, but I don't understand how it works.</div></div></div></blockquote><div class=""><br class=""></div>The switch connects the output of IC1b directly to the output stage IC7. The output of IC1b is very low impedance and is connected directly to the + input of IC7. Therefor, the processed signal (coming in via R52) is completely attenuated (short circuited you might say) by IC1b’s output.<div class=""><br class=""></div><div class="">There might be some bleed but it is attenuated by R52 (10k) over the output impedance of IC1b (extremely low).</div><div class=""><br class=""></div><div class="">Ben</div><div class=""><br class=""></div></div></div></blockquote></div><br clear="all" class=""><br class="">-- <br class=""><div dir="ltr" class="gmail_signature"><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><a href="https://www.instagram.com/colinmuirdorward/" target="_blank" class="">https://www.instagram.com/colinmuirdorward/</a></div><div class=""><a href="https://www.instagram.com/colinmuirdorward/" target="_blank" class="">-<br class=""></a></div><div class=""><a href="https://www.instagram.com/ssdp_synthesis/" target="_blank" class="">https://www.instagram.com/ssdp_synthesis/</a></div></div></div></div></div></div></div>
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