<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">good point Mike. And even at 600, the clipping would be barely noticeable at full volume, thus sayeth the spice man <div><br id="lineBreakAtBeginningOfSignature"><div dir="ltr">Cheers,<div>Chris </div></div><div dir="ltr"><br><blockquote type="cite">On Apr 24, 2024, at 6:48 PM, Mike Bryant <mbryant@futurehorizons.com> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
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I think the designer assumed the use of consumer 32 Ohm headphones rather than the pro 600 Ohm ones. </div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Synth-diy <synth-diy-bounces@synth-diy.org> on behalf of Tom Wiltshire <tom@electricdruid.net><br>
<b>Sent:</b> 24 April 2024 23:24<br>
<b>To:</b> Chris McDowell <declareupdate@gmail.com><br>
<b>Cc:</b> SDIY List <synth-diy@synth-diy.org><br>
<b>Subject:</b> Re: [sdiy] anti pop mosfets in minibrute</font>
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<div class="" style="word-wrap:break-word; line-break:after-white-space">Isn't the problem when the output goes *over* the forward voltage of the diodes? Below that limit , they won't conduct, or barely, anyway. In which case, keep the voltage low, but drive
the current (it's a low impedance headphone output) and no problem. When the mosfets are on, the output is shorted to ground. When they're not, you're ok up to that (roughly) 2Vpp limit.
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<div class="">Am I just catching up on what you've already worked out? Wouldn't be the first time...;)</div>
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<div class="">On 24 Apr 2024, at 21:14, Chris McDowell via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" class="">synth-diy@synth-diy.org</a>> wrote:</div>
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<div class="">hello list, I've been looking at minibrute schematics today and I'm puzzled by the anti pop circuitry in the headphone driver. it -seems- like the body diode of the mosfets would conduct when the signal went below 0.6ish volts (something I've
run into this using mosfets for dc signal muting).</div>
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<div class=""> From the vca page, that signal can be up to 2Vpp. <a href="https://hackabrute.yusynth.net/MINIBRUTE/analog-board/schematics/MiniBrute-08-VCA.pdf" class="">https://hackabrute.yusynth.net/MINIBRUTE/analog-board/schematics/MiniBrute-08-VCA.pdf</a></div>
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<div class="">What am I missing here? Is 2Vpp just fine in this case? Now reading the 2n7002 datasheet I see the forward voltage of the source-drain diode is typ 0.88V, 1.5V max. Did I just answer my own question? 😜</div>
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<div dir="ltr" class="">Cheers,
<div class="">Chris McDowell</div>
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