Subject: Re: Headphone sound pressure level? From: Jose Antonio Almagro Pastor <jalmagro@xxxxxxxx> Date: Wed, 13 Jul 2011 20:50:37 +0200 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>--000e0cd3ff926bcbda04a7f7e423 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Dear Gemma. I don't know about that IEC standard but 113 dB/V is the sensitivity of the device and that is not a maximum pressure level. Maximum level can be estimated from sensitivity, power handling and impedance as power is: W=3DV^2/Z Nominal impedance<http://www.sennheiser.com/sennheiser/home_en.nsf/root/pro= fessional_headphones-headsets_headphones_004974?Open&row=3D2#>64 OhmSound pressure level (SPL)<http://www.sennheiser.com/sennheiser/home_en.nsf/root/professional_he= adphones-headsets_headphones_004974?Open&row=3D2#>102 dB (IEC 268-7)Load rating<http://www.sennheiser.com/sennheiser/home_en.nsf/root/professional_h= eadphones-headsets_headphones_004974?Open&row=3D2#>500 mW Maximum rms voltage is Vmax=3DSQRT(0,5=B764)=3D5,6 V So maximum SPL should be 113+20 log(5,6)=3D 128 dB Now you have two solutions: 102 dB under IEC-268 and 128 dB when loaded with 500 mW, obviously there's a huge difference so I recommend you to just measure the SPL under the closer conditions you'll have on your tests. Best regards. Jose. 2011/7/13 Gemma Rachael Hutchinson <gemma@xxxxxxxx> > Dear all, > > We have a set of Sennheiser HD 280 pro headphones with a "sound pressure > level" of 102 dB "as per IEC 268-7". Since it also states a sound pressur= e > level of 113dB/1V rms, we are unsure exactly what the maximum output leve= l > of these headphones actually is. The impedance is 64ohm. Would anyone kno= w > how to calculate this, or does anyone have access to the full internation= al > standard for headphones (e.g., IEC 60268-7), a preview of which can be fo= und > at the link below? > > http://webstore.iec.ch/**preview/info_iec60268-7%7Bed3.**0%7Den.pdf<http:= //webstore.iec.ch/preview/info_iec60268-7%7Bed3.0%7Den.pdf> > > Thanks, Gemma > --000e0cd3ff926bcbda04a7f7e423 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable =A0=A0 =A0Dear Gemma.<div><br></div><div>=A0=A0 =A0I don't know about t= hat IEC standard but 113 dB/V is the sensitivity of the device and that is = not a maximum pressure level. Maximum level can be estimated from sensitivi= ty, power handling and impedance as power is: W=3DV^2/Z</div> <div><br></div><div><span class=3D"Apple-style-span" style=3D"font-family: = Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 11px; color: rgb(= 51, 51, 51); line-height: 14px; "><table cellpadding=3D"3" cellspacing=3D"0= " border=3D"0" width=3D"530" style=3D"font: normal normal normal 11px/14px = Verdana, Geneva, Arial, Helvetica, sans-serif; color: rgb(51, 51, 51); "> <tbody><tr valign=3D"top" style=3D"font: normal normal normal 11px/14px Ver= dana, Geneva, Arial, Helvetica, sans-serif; color: rgb(51, 51, 51); "><td s= tyle=3D"font: normal normal normal 11px/14px Verdana, Geneva, Arial, Helvet= ica, sans-serif; color: rgb(51, 51, 51); padding-left: 8px; "> <a href=3D"http://www.sennheiser.com/sennheiser/home_en.nsf/root/profession= al_headphones-headsets_headphones_004974?Open&row=3D2#" style=3D"color:= rgb(51, 51, 51); text-decoration: none; "><span class=3D"linkGray" style= =3D"color: rgb(51, 51, 51); text-decoration: none; ">Nominal impedance</spa= n></a></td> <td style=3D"font: normal normal normal 11px/14px Verdana, Geneva, Arial, H= elvetica, sans-serif; color: rgb(51, 51, 51); padding-left: 8px; ">64 Ohm</= td></tr><tr valign=3D"top" bgcolor=3D"#D9D9D9" style=3D"font: normal normal= normal 11px/14px Verdana, Geneva, Arial, Helvetica, sans-serif; color: rgb= (51, 51, 51); "> <td style=3D"font: normal normal normal 11px/14px Verdana, Geneva, Arial, H= elvetica, sans-serif; color: rgb(51, 51, 51); padding-left: 8px; "><a href= =3D"http://www.sennheiser.com/sennheiser/home_en.nsf/root/professional_head= phones-headsets_headphones_004974?Open&row=3D2#" style=3D"color: rgb(51= , 51, 51); text-decoration: none; "><span class=3D"linkGray" style=3D"color= : rgb(51, 51, 51); text-decoration: none; ">Sound pressure level (SPL)</spa= n></a></td> <td style=3D"font: normal normal normal 11px/14px Verdana, Geneva, Arial, H= elvetica, sans-serif; color: rgb(51, 51, 51); padding-left: 8px; ">102 dB (= IEC 268-7)</td></tr><tr valign=3D"top" style=3D"font: normal normal normal = 11px/14px Verdana, Geneva, Arial, Helvetica, sans-serif; color: rgb(51, 51,= 51); "> <td style=3D"font: normal normal normal 11px/14px Verdana, Geneva, Arial, H= elvetica, sans-serif; color: rgb(51, 51, 51); padding-left: 8px; "><a href= =3D"http://www.sennheiser.com/sennheiser/home_en.nsf/root/professional_head= phones-headsets_headphones_004974?Open&row=3D2#" style=3D"color: rgb(51= , 51, 51); text-decoration: none; "><span class=3D"linkGray" style=3D"color= : rgb(51, 51, 51); text-decoration: none; ">Load rating</span></a></td> <td style=3D"font: normal normal normal 11px/14px Verdana, Geneva, Arial, H= elvetica, sans-serif; color: rgb(51, 51, 51); padding-left: 8px; ">500 mW<b= r><br><br></td></tr></tbody></table></span>=A0=A0 =A0Maximum rms voltage is= Vmax=3DSQRT(0,5=B764)=3D5,6 V</div> <div>=A0=A0 =A0So maximum SPL should be 113+20 log(5,6)=3D 128 dB</div><div= ><br></div><div>=A0=A0 =A0Now you have two solutions: 102 dB under IEC-268 = and 128 dB when loaded with 500 mW, obviously there's a huge difference= so I recommend you to just measure the SPL under the closer conditions you= 'll have on your tests.</div> <div><br></div><div>=A0=A0 =A0Best regards. Jose.<br><div class=3D"gmail_qu= ote"><br></div><div class=3D"gmail_quote"><br></div><div class=3D"gmail_quo= te">2011/7/13 Gemma Rachael Hutchinson <span dir=3D"ltr"><<a href=3D"mai= lto:gemma@xxxxxxxx">gemma@xxxxxxxx</a>></span><br> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex;">Dear all,<br> <br> We have a set of Sennheiser HD 280 pro headphones with a "sound pressu= re level" of 102 dB "as per IEC 268-7". Since it also states= a sound pressure level of 113dB/1V rms, we are unsure exactly what the max= imum output level of these headphones actually is. The impedance is 64ohm. = Would anyone know how to calculate this, or does anyone have access to the = full international standard for headphones (e.g., IEC 60268-7), a preview o= f which can be found at the link below?<br> <br> <a href=3D"http://webstore.iec.ch/preview/info_iec60268-7%7Bed3.0%7Den.pdf"= target=3D"_blank">http://webstore.iec.ch/<u></u>preview/info_iec60268-7%7B= ed3.<u></u>0%7Den.pdf</a><br> <br> Thanks, Gemma<br> </blockquote></div><br></div> --000e0cd3ff926bcbda04a7f7e423--