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Hi-End
Hi-End καλώδια και αξεσουάρ
Καλωδια, r l c - crosstalk κλπ.
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<blockquote data-quote="vas silis" data-source="post: 618326" data-attributes="member: 10224"><p><img src="http://i.cmpnet.com/techonline/images/community/content/feature/fiorucci/figure18.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /> </p><p><strong>Figure 18:</strong> The DH340LU5 speaker cable</p><p></p><p></p><p>The DH340LU5 is a cable for the passive speaker, with a 12.5 mm overall diameter, a 5 m length and two Speakon 4 pole connectors (<strong>Figure 18</strong>). The cable shows a flat attenuation in the entire audio band (around -0.1 dB variation), a linear phase variation (only -6 degree) and a cutoff frequency greater than 2.1 MHz. </p><p></p><p>The cable without connectors is the HPC640BK, a flexible 4-conductor twisted loudspeaker cable with an 11.16 m length. Also the cable HPC640BK shows a flat attenuation in the audio band (around -0.1 dB variation).</p><p></p><p>The CMN20 is a multipair cable that consists of 20 couples of conductors with 0.14 mm2 of section, individually insulated with 100% foil shield and 9.80 m length.</p><p></p><p>The cables DH340LU5 and HPC640BK show a similar behavior in terms of frequency response. The DH340LU5 has not significant difference between NEXT and FEXT for each pair of pole; a small difference of behavior has been measured in the crosstalk of the two pole pairs.</p><p></p><p>The CMN20 cable has a different behavior in comparison with the other ones due to the smaller section of conductors.</p><p></p><p></p><p>The results have been analyzed with reference to the standard IEC 61938<img src="http://i.cmpnet.com/techonline/images/community/content/old/features/numbers/two_blue.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /> that defines some characteristics for the cables used to transfer analogue signals between audio systems: <ol> <li data-xf-list-type="ol">speaker cables<ol> <li data-xf-list-type="ol">the usual value for the conductor resistance should be less than 1/100 Z[SIZE=-2]L[/SIZE];</li> <li data-xf-list-type="ol">the usual value for the inductive reactance at the maximum frequency of interest should not exceed 1/3 Z[SIZE=-2]L[/SIZE]; this condition guarantees less than 1 dB loss at the maximum working frequency;</li> </ol></li> <li data-xf-list-type="ol">cables for interconnection between audio systems<ol> <li data-xf-list-type="ol">the usual value for the conductor resistance should be less than 1/10 Z[SIZE=-2]L[/SIZE];</li> <li data-xf-list-type="ol">the usual value for the minimum capacitive reactance for conductors carrying different audio signals should be greater than 1000 Z[SIZE=-2]L[/SIZE] at the highest frequency of interest; this ensure that the relative crosstalk level is approximately of -60 dB;</li> <li data-xf-list-type="ol">the usual value for the minimum capacitive reactance for conductors to screen should be greater than 3 Z[SIZE=-2]S[/SIZE] (impedance of the signal source); this condition ensures less than 1 dB loss at the highest frequency of interest.</li> </ol></li> </ol><p></p><p></p><p></p><p>From the obtained results, for all the examined cables, we can highlight the following considerations: <ol> <li data-xf-list-type="ol">speaker cables<ol> <li data-xf-list-type="ol">all the cables have a cutoff frequency greater than 2 MHz, a value very greater than the bandwidth of audio signals;</li> <li data-xf-list-type="ol">the resistance of the cable (and connectors) is of 0.15 - 0.17 Ω, with 0.03 Ω˜/m; to have the required R < 1/100 Z[SIZE=-2]L[/SIZE] it is only necessary to have Z[SIZE=-2]L[/SIZE] > 100 R = 15-17 Ω;</li> <li data-xf-list-type="ol">the inductance, an important parameter for this kind of cables, is always lower than 4 µH with around 0.7 µH/m. The condition X[SIZE=-2]L,20kHz[/SIZE] < 1/3 Z[SIZE=-2]L[/SIZE] requires that Z[SIZE=-2]L[/SIZE] > 3 X[SIZE=-2]L,20kHz[/SIZE] = 2.3 - 2.7 Ω;</li> <li data-xf-list-type="ol">the attenuation at the maximum frequency is lower than 1/10 of that required (1 dB).</li> </ol></li> <li data-xf-list-type="ol">cables for interconnection between audio systems<ol> <li data-xf-list-type="ol">all the cables have a cutoff frequency greater than 2 MHz, a value very greater than the bandwidth of audio signals;</li> <li data-xf-list-type="ol">the attenuation at the maximum frequency is lower than that required by the standard (1 dB);</li> <li data-xf-list-type="ol">the resistance of the cable (and connectors) is of 0.26 - 1.04 Ω; to have R < 1/10 Z[SIZE=-2]L[/SIZE] it is only necessary to have Z[SIZE=-2]L[/SIZE] > 10 R = 2.6-10.4 Ω;</li> <li data-xf-list-type="ol">to satisfy the condition X[SIZE=-2]C, 20kHz[/SIZE] > 1000 Z[SIZE=-2]L[/SIZE] it is only necessary that Z[SIZE=-2]L[/SIZE] < X[SIZE=-2]C, 20kHz[/SIZE] / 1000, for which Z[SIZE=-2]L[/SIZE] < 16.5 Ω for example for the cable DH200LU5<img src="http://i.cmpnet.com/techonline/images/community/content/old/features/numbers/three_blue.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" />;</li> <li data-xf-list-type="ol">the condition for the minimum capacitive reactance for conductor to screen at 20 kHz greater than 3 Z[SIZE=-2]S[/SIZE] (impedance of the signal source), requires Z[SIZE=-2]S[/SIZE] < 0.33 X[SIZE=-2]C, 20kHz[/SIZE] = 0.33*1.66E+4= 5478 Ω, for example, for the cable DH240LU5<img src="http://i.cmpnet.com/techonline/images/community/content/old/features/numbers/three_blue.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /> .</li> </ol></li> </ol><p></p><p>As a general comment to these results and to correctly analyze the problem related to the cable's impedance and to its variation in the audio band, we must also consider that the impedance of the audio devices connected at the input (source) and output (load) can have a frequency variation.</p><p></p><p>For example the speaker impedance is usually largely dependent on frequency. Real impedance of a nominal 8 ohm speaker, for example, can vary from 6 ohm to 10 ohm (variation can be much higher on some speakers). The nature of the speaker impedance can also change with the frequency from purely resistive to inductive or capacitive.</p><p></p><p>Starting from these considerations, the problem of the cable parameter variation with the frequency becomes of secondary importance for most applications.</p><p></p><p></p><p>Conclusions</p><p>In this paper, we have implemented some characterization tests for Hi-Fi cables in the real conditions of use. In order to guarantee the repeatability of the lumped parameters and crosstalk ratio measurements, an automatic testing system has been adopted. </p><p></p><p></p><p>A wide set of high performance Hi-Fi cables, with and without connectors, have been characterized, evidencing their behavior differences. The measurement of lumped elements, attenuation, and phase-difference has been carried out for different frequency values. For the multipolar cables, the crosstalk characteristics have been measured.</p><p></p><p>The experimental results confirm the overall quality of the tested cables, with reference to IEC standard requirements.</p><p></p><p>Our aim in the next work is to develop other kinds of characterization procedures for high performance Hi-Fi cables. Specifically, the tests on power cables for loudspeakers will be carried out with variable both frequency and load conditions, according to the non linear behavior of real Hi-Fi apparatuses like loudspeakers.</p><p></p><p></p><p>About the Authors</p><p><strong>Giovanni Bucci</strong> received a degree in electrical engineering in 1985 from the University of L'Aquila in Italy. He is now an Associate Professor in Electrical Measurement at the University of L'Aquila. His current research interests include ADC and wireless device testing, multiprocessor-based measuring systems, digital algorithms for real-time measuring instruments, and power measurements. He has authored more than 80 scientific papers.</p><p></p><p></p><p></p><p><strong>Edoardo Fiorucci</strong> received a degree in electrical engineering in 2000 from the University of L'Aquila in Italy. In June 2004, he received a Ph.D. in Electrical and Information Engineering from the same university. He is now a postdoctoral fellow of the Department of Electrical Engineering at the University of L'Aquila. His current research interests include wireless device testing, power quality measurement, virtual instrumentation, smart sensors, and power measurements. He has authored more than 20 scientific papers.</p><p></p><p></p><p></p><p><strong>Fabio Di Nicola</strong> received a degree in electrical engineering in 2003 from the University of L'Aquila in Italy. He is now a Ph.D. student in Electrical Engineering at the university "La Sapienza" of Roma in Italy. His current research interests include analysis and optimization of intervals between periodic calibration for measurement instruments, virtual instrumentation and performance evaluation of Hi-Fi systems.</p><p></p><p><a href="http://www.audiodesignline.com/showArticle.jhtml?articleID=192200304" target="_blank">http://www.audiodesignline.com/showArticle.jhtml?articleID=192200304</a></p></blockquote><p></p>
[QUOTE="vas silis, post: 618326, member: 10224"] [IMG]http://i.cmpnet.com/techonline/images/community/content/feature/fiorucci/figure18.gif[/IMG] [B]Figure 18:[/B] The DH340LU5 speaker cable The DH340LU5 is a cable for the passive speaker, with a 12.5 mm overall diameter, a 5 m length and two Speakon 4 pole connectors ([B]Figure 18[/B]). The cable shows a flat attenuation in the entire audio band (around -0.1 dB variation), a linear phase variation (only -6 degree) and a cutoff frequency greater than 2.1 MHz. The cable without connectors is the HPC640BK, a flexible 4-conductor twisted loudspeaker cable with an 11.16 m length. Also the cable HPC640BK shows a flat attenuation in the audio band (around -0.1 dB variation). The CMN20 is a multipair cable that consists of 20 couples of conductors with 0.14 mm2 of section, individually insulated with 100% foil shield and 9.80 m length. The cables DH340LU5 and HPC640BK show a similar behavior in terms of frequency response. The DH340LU5 has not significant difference between NEXT and FEXT for each pair of pole; a small difference of behavior has been measured in the crosstalk of the two pole pairs. The CMN20 cable has a different behavior in comparison with the other ones due to the smaller section of conductors. The results have been analyzed with reference to the standard IEC 61938[URL="javascript:newWindow('/static/feature_articles/fiorucci/reference2.html')"][IMG]http://i.cmpnet.com/techonline/images/community/content/old/features/numbers/two_blue.gif[/IMG][/URL] that defines some characteristics for the cables used to transfer analogue signals between audio systems: [LIST=1] [*]speaker cables[LIST=1] [*]the usual value for the conductor resistance should be less than 1/100 Z[SIZE=-2]L[/SIZE]; [*]the usual value for the inductive reactance at the maximum frequency of interest should not exceed 1/3 Z[SIZE=-2]L[/SIZE]; this condition guarantees less than 1 dB loss at the maximum working frequency;[/LIST] [*]cables for interconnection between audio systems[LIST=1] [*]the usual value for the conductor resistance should be less than 1/10 Z[SIZE=-2]L[/SIZE]; [*]the usual value for the minimum capacitive reactance for conductors carrying different audio signals should be greater than 1000 Z[SIZE=-2]L[/SIZE] at the highest frequency of interest; this ensure that the relative crosstalk level is approximately of -60 dB; [*]the usual value for the minimum capacitive reactance for conductors to screen should be greater than 3 Z[SIZE=-2]S[/SIZE] (impedance of the signal source); this condition ensures less than 1 dB loss at the highest frequency of interest.[/LIST][/LIST] From the obtained results, for all the examined cables, we can highlight the following considerations: [LIST=1] [*]speaker cables[LIST=1] [*]all the cables have a cutoff frequency greater than 2 MHz, a value very greater than the bandwidth of audio signals; [*]the resistance of the cable (and connectors) is of 0.15 - 0.17 Ω, with 0.03 Ω˜/m; to have the required R < 1/100 Z[SIZE=-2]L[/SIZE] it is only necessary to have Z[SIZE=-2]L[/SIZE] > 100 R = 15-17 Ω; [*]the inductance, an important parameter for this kind of cables, is always lower than 4 µH with around 0.7 µH/m. The condition X[SIZE=-2]L,20kHz[/SIZE] < 1/3 Z[SIZE=-2]L[/SIZE] requires that Z[SIZE=-2]L[/SIZE] > 3 X[SIZE=-2]L,20kHz[/SIZE] = 2.3 - 2.7 Ω; [*]the attenuation at the maximum frequency is lower than 1/10 of that required (1 dB).[/LIST] [*]cables for interconnection between audio systems[LIST=1] [*]all the cables have a cutoff frequency greater than 2 MHz, a value very greater than the bandwidth of audio signals; [*]the attenuation at the maximum frequency is lower than that required by the standard (1 dB); [*]the resistance of the cable (and connectors) is of 0.26 - 1.04 Ω; to have R < 1/10 Z[SIZE=-2]L[/SIZE] it is only necessary to have Z[SIZE=-2]L[/SIZE] > 10 R = 2.6-10.4 Ω; [*]to satisfy the condition X[SIZE=-2]C, 20kHz[/SIZE] > 1000 Z[SIZE=-2]L[/SIZE] it is only necessary that Z[SIZE=-2]L[/SIZE] < X[SIZE=-2]C, 20kHz[/SIZE] / 1000, for which Z[SIZE=-2]L[/SIZE] < 16.5 Ω for example for the cable DH200LU5[URL="javascript:newWindow('/static/feature_articles/fiorucci/reference3.html')"][IMG]http://i.cmpnet.com/techonline/images/community/content/old/features/numbers/three_blue.gif[/IMG][/URL]; [*]the condition for the minimum capacitive reactance for conductor to screen at 20 kHz greater than 3 Z[SIZE=-2]S[/SIZE] (impedance of the signal source), requires Z[SIZE=-2]S[/SIZE] < 0.33 X[SIZE=-2]C, 20kHz[/SIZE] = 0.33*1.66E+4= 5478 Ω, for example, for the cable DH240LU5[URL="javascript:newWindow('/static/feature_articles/fiorucci/reference3.html')"][IMG]http://i.cmpnet.com/techonline/images/community/content/old/features/numbers/three_blue.gif[/IMG][/URL] .[/LIST][/LIST] As a general comment to these results and to correctly analyze the problem related to the cable's impedance and to its variation in the audio band, we must also consider that the impedance of the audio devices connected at the input (source) and output (load) can have a frequency variation. For example the speaker impedance is usually largely dependent on frequency. Real impedance of a nominal 8 ohm speaker, for example, can vary from 6 ohm to 10 ohm (variation can be much higher on some speakers). The nature of the speaker impedance can also change with the frequency from purely resistive to inductive or capacitive. Starting from these considerations, the problem of the cable parameter variation with the frequency becomes of secondary importance for most applications. Conclusions In this paper, we have implemented some characterization tests for Hi-Fi cables in the real conditions of use. In order to guarantee the repeatability of the lumped parameters and crosstalk ratio measurements, an automatic testing system has been adopted. A wide set of high performance Hi-Fi cables, with and without connectors, have been characterized, evidencing their behavior differences. The measurement of lumped elements, attenuation, and phase-difference has been carried out for different frequency values. For the multipolar cables, the crosstalk characteristics have been measured. The experimental results confirm the overall quality of the tested cables, with reference to IEC standard requirements. Our aim in the next work is to develop other kinds of characterization procedures for high performance Hi-Fi cables. Specifically, the tests on power cables for loudspeakers will be carried out with variable both frequency and load conditions, according to the non linear behavior of real Hi-Fi apparatuses like loudspeakers. About the Authors [B]Giovanni Bucci[/B] received a degree in electrical engineering in 1985 from the University of L'Aquila in Italy. He is now an Associate Professor in Electrical Measurement at the University of L'Aquila. His current research interests include ADC and wireless device testing, multiprocessor-based measuring systems, digital algorithms for real-time measuring instruments, and power measurements. He has authored more than 80 scientific papers. [B]Edoardo Fiorucci[/B] received a degree in electrical engineering in 2000 from the University of L'Aquila in Italy. In June 2004, he received a Ph.D. in Electrical and Information Engineering from the same university. He is now a postdoctoral fellow of the Department of Electrical Engineering at the University of L'Aquila. His current research interests include wireless device testing, power quality measurement, virtual instrumentation, smart sensors, and power measurements. He has authored more than 20 scientific papers. [B]Fabio Di Nicola[/B] received a degree in electrical engineering in 2003 from the University of L'Aquila in Italy. He is now a Ph.D. student in Electrical Engineering at the university "La Sapienza" of Roma in Italy. His current research interests include analysis and optimization of intervals between periodic calibration for measurement instruments, virtual instrumentation and performance evaluation of Hi-Fi systems. [url]http://www.audiodesignline.com/showArticle.jhtml?articleID=192200304[/url] [/QUOTE]
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