Re: USB sound cards ("Richard F. Lyon" )


Subject: Re: USB sound cards
From:    "Richard F. Lyon"  <dicklyon@xxxxxxxx>
Date:    Fri, 12 Dec 2014 22:09:17 -0800
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

--001a1134ba647be5bc050a12d9f0 Content-Type: text/plain; charset=UTF-8 It seems not unlikely that headphones (or speakers) might have some reactive elements and resonances, such that some added resistance in the driving circuit would lead to higher damping and a more even response. Someone should do a test, starting with impedance measurements of various headphones to see if they have identifiable resonances. It might turn out that adding resistance is a good thing, for scientific perceptual experiments or otherwise. I wouldn't be surprised either way. Dick On Fri, Dec 12, 2014 at 3:36 PM, Steve Beet <stevebeet@xxxxxxxx> wrote: > This may be a red herring, but I've seen some self-proclaimed "audiophile" > publications which claim that when headphones are driven from a resistive > source impedance of a few tens of Ohms, they "sound better" than when they > are driven from an ideal (very low impedance) voltage source. As far as I > recall, these statements were referring to listening tests of > professional-quality headphones with nominal impedances of 200 Ohms. > > These publications didn't present any analytical measurements to suggest > why > this might be the case, but the output resistance added to many headphone > amps might not be there solely to prevent damage or distortion - it might > also be to persuade audiophiles that they're getting the best sound > quality. > > For music produced and mixed to be listened to via loudspeakers, it may be > that adding a series resistor might indeed make the headphones sound more > like the original mixing engineer or producer intended, but for scientific > perceptual experiments I can't see any advantage in artificially increasing > the resistance. > > Steve Beet > > > -----Original Message----- > From: AUDITORY - Research in Auditory Perception > [mailto:AUDITORY@xxxxxxxx On Behalf Of Bob Masta > Sent: 11 December 2014 17:03 > To: AUDITORY@xxxxxxxx > Subject: Re: USB sound cards > > However, there *is* a problem getting low output impedance as well. The > native design of modern amplifier stages has essentially zero output > impedance due to negative feedback (milliohms or less). That means that if > you connect such an amp to a low-impedance load, the current draw can be > high... high enough to damage the output stages, or at least cause massive > distortion as they go into protective current limiting. Since these are > for > consumer use, where anyone can plug in most anything that fits the jack, > manufacturer's typically add some output impedance. > --001a1134ba647be5bc050a12d9f0 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr">It seems not unlikely that headphones (or speakers) might = have some reactive elements and resonances, such that some added resistance= in the driving circuit would lead to higher damping and a more even respon= se.=C2=A0 Someone should do a test, starting with impedance measurements of= various headphones to see if they have identifiable resonances.=C2=A0 It m= ight turn out that adding resistance is a good thing, for scientific percep= tual experiments or otherwise.=C2=A0 I wouldn&#39;t be surprised either way= .<br><br>Dick<br><br></div><div class=3D"gmail_extra"><br><div class=3D"gma= il_quote">On Fri, Dec 12, 2014 at 3:36 PM, Steve Beet <span dir=3D"ltr">&lt= ;<a href=3D"mailto:stevebeet@xxxxxxxx" target=3D"_blank">stevebeet@xxxxxxxx= om</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"marg= in:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">This may be a re= d herring, but I&#39;ve seen some self-proclaimed &quot;audiophile&quot;<br= > publications which claim that when headphones are driven from a resistive<b= r> source impedance of a few tens of Ohms, they &quot;sound better&quot; than = when they<br> are driven from an ideal (very low impedance) voltage source. As far as I<b= r> recall, these statements were referring to listening tests of<br> professional-quality headphones with nominal impedances of 200 Ohms.<br> <br> These publications didn&#39;t present any analytical measurements to sugges= t why<br> this might be the case, but the output resistance added to many headphone<b= r> amps might not be there solely to prevent damage or distortion - it might<b= r> also be to persuade audiophiles that they&#39;re getting the best sound qua= lity.<br> <br> For music produced and mixed to be listened to via loudspeakers, it may be<= br> that adding a series resistor might indeed make the headphones sound more<b= r> like the original mixing engineer or producer intended, but for scientific<= br> perceptual experiments I can&#39;t see any advantage in artificially increa= sing<br> the resistance.<br> <span class=3D"HOEnZb"><font color=3D"#888888"><br> Steve Beet<br> </font></span><div class=3D"HOEnZb"><div class=3D"h5"><br> <br> -----Original Message-----<br> From: AUDITORY - Research in Auditory Perception<br> [mailto:<a href=3D"mailto:AUDITORY@xxxxxxxx">AUDITORY@xxxxxxxx= A</a>] On Behalf Of Bob Masta<br> Sent: 11 December 2014 17:03<br> To: <a href=3D"mailto:AUDITORY@xxxxxxxx">AUDITORY@xxxxxxxx</a= ><br> Subject: Re: USB sound cards<br> <br> However, there *is* a problem getting low output impedance as well.=C2=A0 T= he<br> native design of modern amplifier stages has essentially zero output<br> impedance due to negative feedback (milliohms or less). That means that if<= br> you connect such an amp to a low-impedance load, the current draw can be<br= > high... high enough to damage the output stages, or at least cause massive<= br> distortion as they go into protective current limiting.=C2=A0 Since these a= re for<br> consumer use, where anyone can plug in most anything that fits the jack,<br= > manufacturer&#39;s typically add some output impedance.<br> </div></div></blockquote></div><br></div> --001a1134ba647be5bc050a12d9f0--


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