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<blockquote data-quote="thylantyr" data-source="post: 2200161" data-attributes="member: 560358"><p>Ideal cables don't exist. In the real world you have</p><p></p><p>to match cables with application because you have</p><p></p><p>resistance, impedance, inductance, capacitance, skin</p><p></p><p>effect... etc.</p><p></p><p>I suppose the ideal cable would have;</p><p></p><p>*zero dc resistance, impedance @ all frequencies</p><p></p><p>*no inductance/capacitance</p><p></p><p>*can't pickup stray signals/interference</p><p></p><p>An analog audio cable {20khz} is 'easy' if the source has</p><p></p><p>low output impedance and the load has high input impedance. Usually product is made this way to reduce</p><p></p><p>loading effects. A manufacturer who doesn't design using</p><p></p><p>low output impedance and high input impedance will have</p><p></p><p>problems with cables. <strong>You now see an opportunity where cables can be perceived to have SQ</strong></p><p></p><p><strong>because the equipment used is poorly designed.</strong></p><p></p><p>Imagine a company that sabotages their preamp and amplifier design in such a manner where a good cable will</p><p></p><p>not function, rather to make it work better you have to buy</p><p></p><p>the special cable. For example, the ABCXYZ preamp and amplifier. You purposely design it so the output impedance and input impedance will only work with your special cables to pass the audio signal without attenuation {low pass filter}.</p><p></p><p>Normally a person would never consider such a product that can't work with ordinary cables but if you have a</p><p></p><p>an established good reputation you can also convince people that your thousand dollar 'special' cables only work</p><p></p><p>best with your gear. /evil eh?</p><p></p><p>Under a normal situation, not an evil one, you can use</p><p></p><p>any cable with good results to pass the analog audio.</p><p></p><p>The cable model also includes inductance and cables have</p><p></p><p>inductance specs but the inductance on those cables</p><p></p><p>are so low that that Rane doesn't even include it their</p><p></p><p>'math' for line driving. Cable capacitance is the bigger</p><p></p><p>enemy and one should look at that spec as it plays a bigger</p><p></p><p>role in the low pass filter formula, this is assuming the</p><p></p><p>source and destination are properly designed, no funny stuff.</p><p></p><p>Regarding the funny stuff. For an unbalanced preamp output you may see opamp outputs used to drive the signal and usually you may see a 50 ohm to 200 ohm resistor on the output of the circuit to dictate output impedance of the product. This qualifies as 'low output' impedance.</p><p></p><p>I remember someone on a forum mentioning a few years ago that Alpine HU's had 10k output impedance and their amps had 47k input impedance. Double check. When I saw that, it raised the 'evil flag' as why they would do this?</p><p></p><p>10,000 ohms is not low output impedance and it's marginal</p><p></p><p>if you have long cable runs in the car. This makes interfacing more difficult if you choose to use a different amp that had less input impedance than 47k ohms. What if your favorite amp was 10k input impedance?</p><p></p><p>If you know the equipment specs first before buying cables then you can figure out if the cable needs to be special or not. Also, you shouldn't buy equipment with high output impedance and low input impedance if you want a good</p><p></p><p>interface between equipment.</p><p></p><p>If you have an output rated for 200 ohms or less and inputs</p><p></p><p>rated for 22k or higher, it's all good, a normal cable is fine.</p><p></p><p>For higher frequencies they try to standardize the impedance, ie 75 ohm coax for RF, for AES/EBU digital {proaudio}</p><p></p><p>the spec is 110 ohms but the tolerance on that spec is loose and cables made for those applications need the lower capacitance cables.</p><p></p><p>DC resistance is rated per foot. That is really not a big</p><p></p><p>concern either unless you plan to pass high current on a small signal wire. I don't know who needs to do this.</p></blockquote><p></p>
[QUOTE="thylantyr, post: 2200161, member: 560358"] Ideal cables don't exist. In the real world you have to match cables with application because you have resistance, impedance, inductance, capacitance, skin effect... etc. I suppose the ideal cable would have; *zero dc resistance, impedance @ all frequencies *no inductance/capacitance *can't pickup stray signals/interference An analog audio cable {20khz} is 'easy' if the source has low output impedance and the load has high input impedance. Usually product is made this way to reduce loading effects. A manufacturer who doesn't design using low output impedance and high input impedance will have problems with cables. [B]You now see an opportunity where cables can be perceived to have SQ[/B] [B]because the equipment used is poorly designed.[/B] Imagine a company that sabotages their preamp and amplifier design in such a manner where a good cable will not function, rather to make it work better you have to buy the special cable. For example, the ABCXYZ preamp and amplifier. You purposely design it so the output impedance and input impedance will only work with your special cables to pass the audio signal without attenuation {low pass filter}. Normally a person would never consider such a product that can't work with ordinary cables but if you have a an established good reputation you can also convince people that your thousand dollar 'special' cables only work best with your gear. /evil eh? Under a normal situation, not an evil one, you can use any cable with good results to pass the analog audio. The cable model also includes inductance and cables have inductance specs but the inductance on those cables are so low that that Rane doesn't even include it their 'math' for line driving. Cable capacitance is the bigger enemy and one should look at that spec as it plays a bigger role in the low pass filter formula, this is assuming the source and destination are properly designed, no funny stuff. Regarding the funny stuff. For an unbalanced preamp output you may see opamp outputs used to drive the signal and usually you may see a 50 ohm to 200 ohm resistor on the output of the circuit to dictate output impedance of the product. This qualifies as 'low output' impedance. I remember someone on a forum mentioning a few years ago that Alpine HU's had 10k output impedance and their amps had 47k input impedance. Double check. When I saw that, it raised the 'evil flag' as why they would do this? 10,000 ohms is not low output impedance and it's marginal if you have long cable runs in the car. This makes interfacing more difficult if you choose to use a different amp that had less input impedance than 47k ohms. What if your favorite amp was 10k input impedance? If you know the equipment specs first before buying cables then you can figure out if the cable needs to be special or not. Also, you shouldn't buy equipment with high output impedance and low input impedance if you want a good interface between equipment. If you have an output rated for 200 ohms or less and inputs rated for 22k or higher, it's all good, a normal cable is fine. For higher frequencies they try to standardize the impedance, ie 75 ohm coax for RF, for AES/EBU digital {proaudio} the spec is 110 ohms but the tolerance on that spec is loose and cables made for those applications need the lower capacitance cables. DC resistance is rated per foot. That is really not a big concern either unless you plan to pass high current on a small signal wire. I don't know who needs to do this. [/QUOTE]
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