<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;">Oooh. Saving this in my handy notes.<br id="lineBreakAtBeginningOfMessage"><div><br><blockquote type="cite"><div>On Oct 15, 2024, at 8:21 AM, Mattias Rickardsson <mr@analogue.org> wrote:</div><br class="Apple-interchange-newline"><div><div dir="ltr"><div dir="ltr">On Mon, 14 Oct 2024 at 22:09, Neil Harper via Synth-diy <<a href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">looks like the stereo output and headphones are being driven by the same<br>
circuit, NE5532's with 220 ohm series resistors. and if I understand the<br>
normalizing properly, the "shorting" situation I was worried about only<br>
happens if the LEFT/PHONES output is used with a TS cable without a<br>
cable in the RIGHT/MONO jack. even then there's still the 220 ohm series<br>
resistor in place so it's not even a short.. wonder if the 5532 would care?<br></blockquote><div><br></div><div dir="ltr" class="gmail_attr">On Tue, 15 Oct 2024 at 00:48, grant <a href="http://musictechnologiesgroup.com/">musictechnologiesgroup.com</a> <<a href="mailto:grant@musictechnologiesgroup.com">grant@musictechnologiesgroup.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">The Pro-One has a mono-for-stereo-headphones/audio output jack, again<br>with the NE5532:<br>Stereo headphones can be plugged directly into the AUDIO OUT jack. The<br>headphones should have a minimum impedance of 600 Ohms,"<br></blockquote><div><br></div><div>As you have pointed out, the signal on the ring will need to handle being permanently shorted to ground if a TS plug is connected.</div><div><br></div><div>Many typical headphones will be around 100-200-300 ohms. Feels a bit underspecified to use an op-amp with 500-1000 ohm load capabilities here, perhaps worth making a proper headphone stage for these outputs?</div><div><br></div><div>/mr</div></div></div>
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