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<blockquote data-quote="thylantyr" data-source="post: 2200180" data-attributes="member: 560358"><p>For analog audio 20khz, cable capacitance plays the big role not the impedance of the cable. Lower cable capacitance is nice but it may be overkill for the given</p><p></p><p>application. The sources output impedance and input impendance of the equipment is also a variable in the math.</p><p></p><p>Cable impedance is more of an issue with high frequencies, ie Mhz or Ghz, see transmission line theory {google}. Coax {video} cable is 75 ohms, SPDIF {digital audio output} is 75 ohms, AES/EBU {proaudio} is 110 ohms but the spec is very loose on AES/EBU, +/-20% 88 ohm - 132 ohm. // rofl //</p><p></p><p>I’m not a cable guru so do some homework to verify my babble. If the spec is loose, that</p><p></p><p>implies that the manufacturer has to design a receiver than can tolerate that range of</p><p></p><p>impedance mismatch, so some folks are using ordinary 75 ohm cable because it's so close</p><p></p><p>to 88 ohm and they run short cable lengths. It works. The anal-philes[tm] fear problems,</p><p></p><p>loss of digital bits and.or fugly digital signals that can be interpreted wrong by the D/A</p><p></p><p>converters. They don't want to take the risk so they will use 110 ohm 'digital' cable.</p><p></p><p>For SPDIF to AES interfacing, aka home audio CD player that connects to your</p><p></p><p>Behringer DCX which only has AES digital inputs, some of the anal-philes are modding</p><p></p><p>the Behringer by inserting a small 75 ohm to 110 ohm impedance matching transformer.</p><p></p><p>The mod is simple, you place this ****** on the PCB board where the AES signal inputs,</p><p></p><p>the other side of the ****** is now 75 ohm for SPDIF input. This is the politically correct</p><p></p><p>way to do it. In the world of high frequency, funny stuff can happen and you need to</p><p></p><p>match impedance.</p><p></p><p>For 20khz analog audio the impedance is really not an issue, the audio band is snail slow</p><p></p><p>compared to RF or digital transmission, you can get away with almost any type of cable,</p><p></p><p>even the cheap rat shack or home depot ‘dollar’ audio cables work. The reason I don't</p><p></p><p>buy those cheap cables is reliability issues. How many times have you worked on audio</p><p></p><p>using the same cables and the constant insertion of the cable cause intermittent audio</p><p></p><p>problems because the cable weaken over time. Later you find audio intermittent problems and you have to debug the system and it comes down to ‘bad cables’.</p><p></p><p>Been there, done that. The RCA end where the cable meets the wire starts to 'break' and</p><p></p><p>you get intermittent contact and when wiggling the cable the audio cuts in and out.</p><p></p><p>When I was doing car audio, everyone was always tweaking on the systems and wires</p><p></p><p>broke like this. When I was looking for Belden cable decades ago the goal was to find</p><p></p><p>cheap twisted pair with heavy gauge wire to make them gorilla proof on handling. That is</p><p></p><p>why I picked the 8760, 18 awg wire cable.</p><p></p><p>Today, it appears to be a good choice as when I used it with Dayton RCA's and Tech</p><p></p><p>Flex, the fit was perfect, kinda weird eh? I was hoping to find better cable – just because --- but those digital AES cables are 24 awg. Normally not a problem for permanent</p><p></p><p>installs, but for the DIY'er who likes to fvck with their stereos all the time, I don't want</p><p></p><p>the thin wire to break with abuse. /// lol ///</p><p></p><p>That cable is about 50 mils smaller in diameter than 8760 and to make it fit with the</p><p></p><p>Dayton RCA so it's tight you probably have to add some layers of heatshrink tubing</p><p></p><p>to thicken up the cable jacket on the end. No big deal, just another step in the RCA</p><p></p><p>making process.</p><p></p><p>If you are handing audio cables on a regular basis, the DIY microphone cable looks good.</p><p></p><p>The cable is very flexible, they don't tin the copper wires to keep it flexible and they use</p><p></p><p>alot of fine wire to make the whole strand, copper braiding which won't 'break' vs. foil</p><p></p><p>over time, and the rubber housing gives it resistance to abuse, cool for audio but cost a lot</p><p></p><p>of money, 2x - 3x more money than ordinary twisted pair.</p><p></p><p>For home audio, can you find a jack of all trades wire to do unbalanced, balanced, and</p><p></p><p>video ?</p><p></p><p>You can use 75 ohm coax cable for video, use it for analog audio but you can’t use it for</p><p></p><p>balanced as in pro audio gear because it has only one center conductor, balanced requires two. You can find 'multi-wire' coax cable. It's smaller coax cables all inside a common</p><p></p><p>jacket. The question is, how stiff the cable as a whole? That Monster RG6 that the guy on PE recommended said it’s more flexible than RG59 coax, he likes it a lot. The price is cheaper than Belden 9259 coax, but you won’t be able to do balanced interconnects.</p><p></p><p>I also found out that the Beldfoil {Belden's special foil} is more like metalized plastic so</p><p></p><p>it doesn't tolerate abuse like a microphone cable would be - but for permanent installs –</p><p></p><p>it doesn’t matter. I think it can handle a lot of abuse from what I can tell but not everyday abuse. ? Belden claims 100% shielding for RF using the foil, they also claim braided</p><p></p><p>shielding is 90% for the higher grade wire but braided copper is better for lower</p><p></p><p>frequency shielding. Double check, I thought that is what I read on the link I provided.</p><p></p><p>I don't think one has to worry a lot about this in an household installation where wires are</p><p></p><p>short and you don't have crazy interference problems and you don’t do much tweaking</p><p></p><p>where cables are getting abused a lot.</p><p></p><p>In my case, perhaps your case where we mix home audio {unbalanced} with proaudio</p><p></p><p>{balanced}, the regular twisted pair cable would be fine for the analog interconnects.</p><p></p><p>What about the CD player digital output to proaudio input? If you choose this route</p><p></p><p>do you use AES 110 ohm cable or 75 ohm cable? If you cheat you can try AES cable to</p><p></p><p>interface the CD player to Behringer {or any pro audio equipment that is AES} and use</p><p></p><p>that same cable for the rest of the analog DIY interconnects. The problem I see is the SPDIF output might not be happy with 110 ohm cable vs. 75 ohm. I don’t know what the</p><p></p><p>tolerance is for SPDIF and I don’t know how picky the output is. You can use ~75 ohm</p><p></p><p>cable instead and hopefully the AES input can tolerate the mismatch, it’s suppose to handle cable as low as 88 ohm per spec. 75 is close to 88 : hehe:</p><p></p><p>But if you modd the equipment from AES to SPDIF then you should use 75 ohm cable.</p><p></p><p>You can buy an adapter to convert SPDIF to AES too.</p><p></p><p>The comedy gets worse. If you like the Behringer DCX2496 and later want the equalizer</p><p></p><p>DEQ2496 and use the DEQ on the front end, ie</p><p></p><p>CD player digital output -&gt; DEQ -&gt; DCX</p><p></p><p>then the DEQ has both AES and SPDIF interface -- rofl .. Most people are using SPDIF</p><p></p><p>output on the CD player into SPDIF on the DEQ, then DEQ output {AES} to DCX input {AES}. /// hehe ///</p><p></p><p>You can use 75 ohm to feed the DEQ then AES cable to feed DEQ -&gt; DCX</p><p></p><p>It's comedy when trying to interface home audio digital to proaudio, but like I said .. people cheat because the AES spec is so loose. Nobody has complained yet, only the elite</p><p></p><p>golden ear anal-phile who worries about the impedance mismatch that may yield bit loss</p><p></p><p>or fugly digital signals. Keep cables short to minimize issues.</p><p></p><p>If proaudio is not in the equation, then one can use coax to do analog, digital audio and</p><p></p><p>video interconnects, ie that monster cable RG6 cable {vs. RG59}. When you</p><p></p><p>throw in proaudio into the mix you have balanced analog cable requirements that needs</p><p></p><p>two conductors, typically they use the twisted pair cable I mentioned, for digital</p><p></p><p>they use the lower capacitance AES cable.</p><p></p><p>I might make more sense to have two cable types for DIY interconnects instead of</p><p></p><p>finding one that does it all. I don't like stiff cables as in thicker coax, so you may desire more flexible coax like the Monster cable mentioned. I’m sure someone else makes</p><p></p><p>some that is flexible, I don’t have access to try all these cables. // rofl //</p><p></p><p>But with coax you need the special tooks to do a nice job, cost money for those crimpers.</p><p></p><p>With twisted pair no special tools are needed.</p><p></p><p>Then for the proaudio needs, maybe get the AES cable for analog and digital interconnects but you still have that SPDIF to AES issue think about.</p></blockquote><p></p>
[QUOTE="thylantyr, post: 2200180, member: 560358"] For analog audio 20khz, cable capacitance plays the big role not the impedance of the cable. Lower cable capacitance is nice but it may be overkill for the given application. The sources output impedance and input impendance of the equipment is also a variable in the math. Cable impedance is more of an issue with high frequencies, ie Mhz or Ghz, see transmission line theory {google}. Coax {video} cable is 75 ohms, SPDIF {digital audio output} is 75 ohms, AES/EBU {proaudio} is 110 ohms but the spec is very loose on AES/EBU, +/-20% 88 ohm - 132 ohm. // rofl // I’m not a cable guru so do some homework to verify my babble. If the spec is loose, that implies that the manufacturer has to design a receiver than can tolerate that range of impedance mismatch, so some folks are using ordinary 75 ohm cable because it's so close to 88 ohm and they run short cable lengths. It works. The anal-philes[tm] fear problems, loss of digital bits and.or fugly digital signals that can be interpreted wrong by the D/A converters. They don't want to take the risk so they will use 110 ohm 'digital' cable. For SPDIF to AES interfacing, aka home audio CD player that connects to your Behringer DCX which only has AES digital inputs, some of the anal-philes are modding the Behringer by inserting a small 75 ohm to 110 ohm impedance matching transformer. The mod is simple, you place this ****** on the PCB board where the AES signal inputs, the other side of the ****** is now 75 ohm for SPDIF input. This is the politically correct way to do it. In the world of high frequency, funny stuff can happen and you need to match impedance. For 20khz analog audio the impedance is really not an issue, the audio band is snail slow compared to RF or digital transmission, you can get away with almost any type of cable, even the cheap rat shack or home depot ‘dollar’ audio cables work. The reason I don't buy those cheap cables is reliability issues. How many times have you worked on audio using the same cables and the constant insertion of the cable cause intermittent audio problems because the cable weaken over time. Later you find audio intermittent problems and you have to debug the system and it comes down to ‘bad cables’. Been there, done that. The RCA end where the cable meets the wire starts to 'break' and you get intermittent contact and when wiggling the cable the audio cuts in and out. When I was doing car audio, everyone was always tweaking on the systems and wires broke like this. When I was looking for Belden cable decades ago the goal was to find cheap twisted pair with heavy gauge wire to make them gorilla proof on handling. That is why I picked the 8760, 18 awg wire cable. Today, it appears to be a good choice as when I used it with Dayton RCA's and Tech Flex, the fit was perfect, kinda weird eh? I was hoping to find better cable – just because --- but those digital AES cables are 24 awg. Normally not a problem for permanent installs, but for the DIY'er who likes to fvck with their stereos all the time, I don't want the thin wire to break with abuse. /// lol /// That cable is about 50 mils smaller in diameter than 8760 and to make it fit with the Dayton RCA so it's tight you probably have to add some layers of heatshrink tubing to thicken up the cable jacket on the end. No big deal, just another step in the RCA making process. If you are handing audio cables on a regular basis, the DIY microphone cable looks good. The cable is very flexible, they don't tin the copper wires to keep it flexible and they use alot of fine wire to make the whole strand, copper braiding which won't 'break' vs. foil over time, and the rubber housing gives it resistance to abuse, cool for audio but cost a lot of money, 2x - 3x more money than ordinary twisted pair. For home audio, can you find a jack of all trades wire to do unbalanced, balanced, and video ? You can use 75 ohm coax cable for video, use it for analog audio but you can’t use it for balanced as in pro audio gear because it has only one center conductor, balanced requires two. You can find 'multi-wire' coax cable. It's smaller coax cables all inside a common jacket. The question is, how stiff the cable as a whole? That Monster RG6 that the guy on PE recommended said it’s more flexible than RG59 coax, he likes it a lot. The price is cheaper than Belden 9259 coax, but you won’t be able to do balanced interconnects. I also found out that the Beldfoil {Belden's special foil} is more like metalized plastic so it doesn't tolerate abuse like a microphone cable would be - but for permanent installs – it doesn’t matter. I think it can handle a lot of abuse from what I can tell but not everyday abuse. ? Belden claims 100% shielding for RF using the foil, they also claim braided shielding is 90% for the higher grade wire but braided copper is better for lower frequency shielding. Double check, I thought that is what I read on the link I provided. I don't think one has to worry a lot about this in an household installation where wires are short and you don't have crazy interference problems and you don’t do much tweaking where cables are getting abused a lot. In my case, perhaps your case where we mix home audio {unbalanced} with proaudio {balanced}, the regular twisted pair cable would be fine for the analog interconnects. What about the CD player digital output to proaudio input? If you choose this route do you use AES 110 ohm cable or 75 ohm cable? If you cheat you can try AES cable to interface the CD player to Behringer {or any pro audio equipment that is AES} and use that same cable for the rest of the analog DIY interconnects. The problem I see is the SPDIF output might not be happy with 110 ohm cable vs. 75 ohm. I don’t know what the tolerance is for SPDIF and I don’t know how picky the output is. You can use ~75 ohm cable instead and hopefully the AES input can tolerate the mismatch, it’s suppose to handle cable as low as 88 ohm per spec. 75 is close to 88 : hehe: But if you modd the equipment from AES to SPDIF then you should use 75 ohm cable. You can buy an adapter to convert SPDIF to AES too. The comedy gets worse. If you like the Behringer DCX2496 and later want the equalizer DEQ2496 and use the DEQ on the front end, ie CD player digital output -> DEQ -> DCX then the DEQ has both AES and SPDIF interface -- rofl .. Most people are using SPDIF output on the CD player into SPDIF on the DEQ, then DEQ output {AES} to DCX input {AES}. /// hehe /// You can use 75 ohm to feed the DEQ then AES cable to feed DEQ -> DCX It's comedy when trying to interface home audio digital to proaudio, but like I said .. people cheat because the AES spec is so loose. Nobody has complained yet, only the elite golden ear anal-phile who worries about the impedance mismatch that may yield bit loss or fugly digital signals. Keep cables short to minimize issues. If proaudio is not in the equation, then one can use coax to do analog, digital audio and video interconnects, ie that monster cable RG6 cable {vs. RG59}. When you throw in proaudio into the mix you have balanced analog cable requirements that needs two conductors, typically they use the twisted pair cable I mentioned, for digital they use the lower capacitance AES cable. I might make more sense to have two cable types for DIY interconnects instead of finding one that does it all. I don't like stiff cables as in thicker coax, so you may desire more flexible coax like the Monster cable mentioned. I’m sure someone else makes some that is flexible, I don’t have access to try all these cables. // rofl // But with coax you need the special tooks to do a nice job, cost money for those crimpers. With twisted pair no special tools are needed. Then for the proaudio needs, maybe get the AES cable for analog and digital interconnects but you still have that SPDIF to AES issue think about. [/QUOTE]
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