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<blockquote data-quote="Rob Timmerman" data-source="post: 138567" data-attributes="member: 172">Re: Educate me:&nbsp; AES cablingAs Frank has alluded to, the length of the cable and the wavelength of the signals matter in how you model the cable.&nbsp; For cables that are &quot;short&quot; relative to the wavelength of the signal, one typically models the cable as a lumped impedance (with R, L, and C values from the cable properties, typically length-dependant).&nbsp; This is the case for audio cables in almost all cases we run into in this industry.For cables that are not electrically &quot;short&quot; relative to the wavelength of the signal, one typically models the cable as a transmission line with loss.&nbsp; In these cases, things like characteristic impedance and proper termination matter, and it is no longer valid to model the cable as a simple lumped impedance.Cable capacitance can indeed alter the rise and fall times of digital data, but this is typically taken into account in the design of the digital system (and is one of the reasons for maximum cable length specifications).The lengths at which a cable is no longer &quot;electrically short&quot; are given below for some frequencies of interest.&nbsp; All assume that the cable has a velocity factor of 0.6667, and that the maximum length for something to be electrically short is 1/10 the wavelength.4khz (telephone-quality audio): 5km20khz (high quality audio): 1km250khz (DMX): 80m6.144Mhz (AES audio): 3.25m</blockquote>

[QUOTE="Rob Timmerman, post: 138567, member: 172"] Re: Educate me: AES cabling As Frank has alluded to, the length of the cable and the wavelength of the signals matter in how you model the cable. For cables that are "short" relative to the wavelength of the signal, one typically models the cable as a lumped impedance (with R, L, and C values from the cable properties, typically length-dependant). This is the case for audio cables in almost all cases we run into in this industry. For cables that are not electrically "short" relative to the wavelength of the signal, one typically models the cable as a transmission line with loss. In these cases, things like characteristic impedance and proper termination matter, and it is no longer valid to model the cable as a simple lumped impedance. Cable capacitance can indeed alter the rise and fall times of digital data, but this is typically taken into account in the design of the digital system (and is one of the reasons for maximum cable length specifications). The lengths at which a cable is no longer "electrically short" are given below for some frequencies of interest. All assume that the cable has a velocity factor of 0.6667, and that the maximum length for something to be electrically short is 1/10 the wavelength. 4khz (telephone-quality audio): 5km 20khz (high quality audio): 1km 250khz (DMX): 80m 6.144Mhz (AES audio): 3.25m [/QUOTE]

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