Pragmatic 19: I'll Take The Gold-free Extra-Oxygen Cable Please

7 April, 2014


Tackling two types of common cable, Speaker cable and HDMI cables. HDMI some obsess over gold plating; Speaker cable some obsess over OFC. Which is worth the extra money or are neither? Hardcore audiophiles may be upset by the contents of this episode.

Transcript available
Welcome to Pragmatic. Pragmatic is a weekly discussion show contemplating the practical application of technology. Exploring the real-world trade-offs, we look at how great ideas are transformed into products and services that can change our lives. Nothing is as simple as it seems. This episode is brought to you by Squarespace. Squarespace is the all-in-one platform that makes it fast and easy to create your own professional website, portfolio, and online store. For a free trial and 10% off, visit and enter offer code MARS, M-A-R-S, at checkout. A better web starts with your website. Today's show is also brought to you by Audible. Please visit for your free audio book download. We'll talk a little bit more about our sponsors later on in the show. I'm Ben Alexander and my co-host is John Chiggy. How you doing, John? - I'm doing very well. How you doing, Ben? - Doing well. - Fantastic. Well, a couple of thanks this episode. I wanna say a special thanks to Dave Legate, who I've thanked previously on the show. He wrote an excellent article about IPv6 that was inspired by episode 16, which was one man's hopes and dreams of an RF bubble. I'll do a proper follow-up show on that at some point in the next week or two when I get some time, but I just wanna say thank you. And if you're interested, is a link for that in the show notes. Also, thank you for the iTunes reviews. They keep coming in, they just keep coming, and we appreciate every one of them. This week though, specifically, I'd like to call out one in particular, which came in on the German iTunes store from someone by the name of Flavor Dynamics. I'm reasonably sure that's not their actual personal name, that's okay. Anyway, technically the outro music is from 1991, not the 1980s, and I doubt it was ever played in an elevator at any stage. I've actually wrote an article describing all of its history on Tech Distortion, there's a link for that in the show notes, and it's one of my personal favorite tunes it's called Space Debris and in fact we might just queue that up right now okay well now that that's out the way today's episode then you know what it's about, don't you? I do know what it's about. I'm prepping my door locks, putting bars on the windows. Hopefully the flyout from from audio files will not be too bad. They may hunt me down and kill me. I hope not. In any case, so today I would like to talk about the two of the biggest, how should I call them, I guess hotly debated topics in cabling and that is in consumer cabling anyway. It sounds like a great trade magazine, "hotly debated topics in cabling". Yeah, it does actually. Someone should do that. Anyway, so I'm going to talk about oxygen-free copper cables and I'm also going to talk about gold plating of cable connectors plugs. It may sound like a little bit of a weird topic. I I only added it to the list this week and it was one of those ones that when someone suggested I talk about it, it was one of those things that never occurred to me to talk about this but I have actually done a lot of research into this and industrially speaking I've also had a bit of experience particularly with shielded cables and so on. So honestly I'm surprised I didn't think of talking about this sooner. But in any case, we'll kick off with oxygen free copper. only difference between oxygen-free copper and normal copper, obviously it's still just copper, but when it's melted down it's done, OFC copper is melted down in, it's done in an inert gaseous environment. That is to say, oddly enough as the name would suggest, it's oxygen-free, right, no oxygen in the air. But technically it's not 100% free from oxygen, so there's still some oxygen in it. In order to qualify to be called OFC, it has to be less than 10 parts per million oxygen in the copper. So it's pretty minute amount, very very small amount of it but still technically not zero. So they say oxygen free, it's not an absolutist thing, it's as good as. Anyway, OFC is most common in the consumer space as being the figure eight speaker wire and they call it figure eight because if you chop the cable and you look at the cross section of the cable it looks like the number eight. These particular cables are the ones that run from the amplifier out to your speakers. Now, OFC cable has usually got a nice fancy sheath on the cable. So you've got the copper and conductor in the middle and you've got the plastic sheath. Well, if it's made of plastic or PVC or whatever it's made out of, the specific kind of plastic that it's made out of, but anyway. But OFC cables, they like to make fancy and sometimes you'll get a nice clear sheath on them so that you can see the pretty copper inside and look at oh this is very nice and expensive i can see the wire some of them have got i had some rfc cable once that had a blue tinge but it was still essentially transparent so you could see the copper but it was you know again it sort of had that strange blue sort of hue to it but generally rfc cable is is either partially transparent or not or um or slightly tinged anyway i'm not really sure why they do that i think it's just to show off the fact that it's got copper in it, which is weird because all the cables have got copper in them. So essentially, OFC configurations that I've done, I did a whole bunch of digging on this on exact details for OFC cables. So I've picked a couple and they're listed in the show notes. Feel free to look through the specs if you want to. But I guess before we jump into the configurations, it's important to just quickly cover the way that cables are put together. So solid copper, a solid copper core, it would seem like that's what you would do. You would just get a bit of copper, you draw the wire out because one of the properties of a metal is whether or not it is ductile, can be drawn into a wire. So you would think you would draw the copper into a wire and that wire would be whatever diameter it is and it would have a cross-sectional area of 1.5 square millimeters and it'll be a nice solid strand of copper and you think yeah that'd be the simplest thing to do right just put some plastic over the outside of it and you're done but the problem with that is that that's actually not very flexible and the problem with cables with metal is that most metals in fact all metals are crystalline structures and as you bend and then unbend them if you know what I mean like you sort of make a crease and then you flatten the crease out or you you bend it back and forth and back and forth, what it does is it introduces dislocations into the structure of the crystal in the actual metal and those dislocations eventually build up and build up until a series of dislocations travel all the way through the entire piece of metal. That's a wear-out mechanism for the metal and that wear-out mechanism is called fatigue stress. That cracking caused by repeated movement back and forth and back and forth back and forth One of the ways that that is made worse is if you have a supposedly flexible cable and it's just one solid strand of copper. So essentially there's no give in that at all. It'll simply just because of the thicker it is, the thicker that cable is, you know, it's going to essentially suffer from fatigue stress far more readily than if you were to get, let's say, five or seven small cores, much smaller cores, and you then bundle them together. them together in a group. Think of it like a hexagon. With seven of them, you get a hexagon, you get one in the center. So if you can imagine a little cluster of wires, and those are the individual cores, and I would call that a seven. That's a seven strand. That configuration is far more flexible because as you bend the cable, the copper on the inside of the curve will actually bend slightly and push apart the others, while the others on the outside will actually pull in and change their configuration ever so slightly but that prevents them from getting a solid dislocation through them. The effect improves as you add more cores. So by the time you go up to several hundred cores that's when the cables start to be called ultra flexible. Each of the individual cores themselves can't actually carry a heck of a lot of current but you've got a hundred of them and so it all adds up. So the idea is the more the more cores or strands you have in the cable, the more flexible the cable is. But perhaps not surprisingly, the more expensive the cable is going to be. So the thing that I found interesting was that having a look at OFC cables, I didn't find any of them that had a small strand count. So I say a small strand count until like 7, 15, 21. That's a small strand count in relative terms. The one I saw, and the one that I'm going to use for examples in this in this discussion is actually 189 cores. So that particular one, each of the cores is only 0.1. That's his diameter. So when you quote that as a cable you would say that's a 189/0.1. I then looked at an alternative which is like a cheaper speaker wire, figure-eight speaker wire, and it had a different core configuration. It wasn't OFC and its configuration is 7/025 sometimes in the 0.25 and if you're talking in the lingo then you'll usually leave the decimal point out as it's assumed so you'd have like 7025 and that's your cable configuration 7020 whatever and what you get used to after a while is you sort of get because you deal with cables long enough like I have and people say "7020 yeah okay that's 1.25 square cable" So that's the cross-sectional area. So what they do is they take the cross-sectional area of each of the strands and they multiply that by the number of strands and that gives you your total effective cross-sectional area for the cable. 189.01 is also 1.5 square mil, the same as 7025 is a 1.5 square mil cross-sectional area. So they both have the same essential cross-sectional area. So then you might say to yourself, "Well, that's great. So what does that mean?" And you would think that with the same cross-sectional area, they would both carry the same amount of current. Assume they're both made out of standard copper, they're not made out of OFC. So which cable do you think would carry more current, more AC current? Would it be the 189 strand or the 7 strand? Ben, what's your guess? 189 strand. Oh, guessed correctly. Yes. Yes. Absolutely. Nice. And the reason for that is not... I don't think it's exactly obvious, but there's an effect that they call the "skin effect" when you're dealing with alternating current signals, of which anything except DC power you can consider an AC signal. And when that happens, because of the varying of the current, the electrons tend to be forced to, well forced, they tend to go around the outside of the actual strand. So the electrons themselves, you'll find the majority of electrons are in the outer skin, if you like, of the strand, and there's hardly any in the center. So in other words, the more strands you add, the more physical area around the outside there is for the electrons to essentially use, or they prefer to use, and hence therefore it'll have less resistance. It's exactly the same idea as ACSR, which actually that stands for Aluminium Conductor Steel Reinforced, and that's actually what they make power lines out of. So the power lines you see in the streets, the ones hanging from the overheads, are typical ACSR. And the idea is you have a steel conductor in the center, which is the main actual, takes the load of the cable, but outside, around the outside clamped to the outside you'll have aluminium conductors. So the aluminium essentially has, you know, you'll have like dozen of little, these much smaller diameter cables around the outside and they increase the amount of effective current that these things can carry. So for the two cables that I've chosen, the 18901 and the 7025, we're talking about ohms and ohms for resistance, and these are in distances in metric apologies, but anyhow 11.7 ohms per kilometer is the resistance of the RFC cable, remembering lower numbers are better for resistance, and for our cheaper economy example it's 55.2 ohms per kilometer. So if you look at the numbers it's roughly five times worse going with a cheap cable. But the numbers can be a little bit deceptive if you just think of them like that. The bottom line, 11.7 ohms per kilometer. That's per thousand meters, which is quite a ways over, what was that, 1.6 miles, so it'd be about, probably about 0.6 of a mile, something like that. quite a lot of cable and I don't know about you but it's not 0.6 of a mile from my amplifier to the speaker in the back of the room. I mean unless I took the cable and coiled it up in the bottom of the room for some reason I'd actually have a coil big enough you could probably use as a cubby house or something but you know that's just crazy right? Well later on we'll look at the exact detail of how that shakes out but the thing is if you actually look at an individual strand, an identical diameter strand from one of from an OFC copper cable to an OFC, a non-OFC strand of copper, the OFC only gives you one percent better conductivity. In other words, its resistance is one percent less than non-OFC copper, standard copper. So the gain there is minuscule. The gain you're getting, that whole 11.7 ohms versus 55.2 ohms, that's coming from the fact that it's got 189 cores, not from the fact that it's OFC. It's kind of deceptive to say the OFC cable is better. Well yeah it's better, but it's better because it's got a different core configuration, not just because the OFC. I mean, is one percent better? Yeah, okay, that's really not worth bothering with. So I do wonder half the time if they fudge the numbers and say "oh yeah, well we'll make the OFC cables out of these really high strand counts because that's going to give us a better overall resistance because I see see see OFC is so much better you know I often wonder if that's the the motivation but in any case look those are those are some of the numbers. Bottom line adding cores will give you flexibility but it costs more to produce forget the OFC it's still going to cost more to make 189 strand cable than a seven strand cable. Now obviously you've got to pull a hell of a lot more cores. You've got to draw that many more cores out of your copper, it's going to take a long more time. You've got to spin them all together, that's going to be a more complex thing with 189 threads versus 7. So it's going to be more expensive to build this cable but it'll be a lot more flexible. So I guess that's a plus and it'll have a lower resistance, that's another plus. There was also a claim I read somewhere, I tried hard to find this link but anyway years ago I read this thing claiming that using an OFC cable improves the noise performance. So if you get a standard figure eight cable it will perform worse with noise than an OFC cable and I distinctly remember reading that and in case anyone out there is thinking that has anything to do with noise it has completely 100% nothing to do with noise. OFC will not affect noise performance at all. So in case anyone out there had that as a preconception, take my word for it. No difference. So we're very happy this week to welcome a new sponsor and Ben, can you tell us a little bit about Squarespace? Sure. Squarespace is the all-in-one platform that makes it fast and easy to create your own professional website, portfolio, and online store. Now if you're someone who listens to a lot of podcasts, I'm sure you've heard of Squarespace, but I'm going to try and go back to to the basics of why it's such a great solution by explaining why and how we've used it at Fiat Lux to build a network website quickly and on a minimal budget. So first, it's simple and easy, and this really counts for a lot. You start by selecting one of the professionally designed templates. There's a variety of styles, but there's definitely a Squarespace look, clean, plenty of white space, and an emphasis on imagery. The templates are deferential to your content and their responsive design. You don't need a different layout for different screens. You can tell when a site has been designed with mobile in mind, or when the designer was thinking only of a big screen. And it's subtle, but it makes a difference. Having those careful decisions being made for you ahead of time, it's a huge plus. It can save you hours and days of reworking designs, content, and general site structure. Now maybe you want to handle all that stuff yourself. Sure, you can do that with Squarespace in a few different ways. Either through Layout Engine, which is their drag and drop content management system. Or if you want to get a little bit deeper, you can edit the CSS manually. And if you want complete design freedom, you can ditch the templates entirely and use developer mode. But really, is that what you want to spend your time doing? Or do you want to be working on your business? For me, the choice was easy. I'd look for the best template I could find to start with and tweak it as needed. Iteration, not invention. So when I got started, I began with native, which is a really clean and simple single column layout. It works great for a single podcast, but almost immediately when I realized I was going to be doing more than one show that I wanted to build a network, I knew this wasn't gonna work. So what you see now with very minimal changes is Avenue. Avenue has this great grid index, which is what we use to display the show art for the different podcasts on the network. I'll get compliments for the look of the site, and it's always really embarrassing as I haven't done much to tweak the template. I think almost everything I have done has made it worse. So all this time I've been experimenting with different backgrounds for hosting the media, different stat services, different ways of organizing individual pages structurally, the RSS feeds, different players. I've really tried everything. And right now you can see a pretty good variety of those options in play on the site, ranging from hosting 100% of the stuff using Squarespace's built-in audio and RSS options to combinations of things like Simplecast and Libsyn on the backend and Squarespace up front, as well as just balancing some of the new shows we've brought on right out to their existing sites. Now did we get everything right 100% up front? No, we're still iterating and we're still learning. And that's why Squarespace's simplicity, ease of use, and focus on solving the big problems and not getting sidetracked by edge cases actually makes it such a great tool. We can experiment easily, quickly, and cheaply, get fast feedback, and go from there. And while we're learning, we've got a great site and we're paying eight bucks a month, so what's not to like? So if you've got an idea, you've got a vision for a blog or a podcast or a small business or a big business, whatever, what are you waiting for? Go get your feet wet and start a trial with no credit card required and start building your website today. And if you wanna save a little money and show your support for Pragmatic at the same time, you can get 10% off by visiting and entering offer code MARS, that's M-A-R-S, at checkout. A better web starts with your website. - Thank you very much for that, Ben. Okay, so now we're gonna talk a little bit about gold plating. Gold plating is what some companies push for their plugs and sockets, although typically it's for cables, hence it's typically plugs because most cables are plugs and the sockets are in the actual equipment. They sell gold connectors for a whole bunch of reasons. They say that it's It's a much lower resistance to go with gold. It's much more... it's just better because gold is like expensive and that means it must be good or something. I don't know. I'm trying to remember exactly what the big attraction is. I mean it looks nice. I mean yeah it's gold right? It's like wow this must be good. The truth is that the contact resistance of gold is really... gold as a conductor is really not that great a conductor. It works. Sure it works but honestly compared to something like aluminium, it's really not that fantastic. I mean it works and it's fine. It's not going to hurt your coils too much, especially over the sorts of cables we're talking about. We're talking about cables that are carrying milliamps of current. They're not at most maybe 200 milliamps or something through these connectors for the signal connectors because these are data signals that we're sending. Because the gold plating they'll do, and I guess I'll pick on HDMI cables because, well, let's face it, HDMI cables have become a problem because everything's going HDMI now. We've got HDMI on most computers these days. I say most computers. My MacBook Air doesn't have it. Anyhow, but the Mac Mini does, for example. Most laptops will have a HDMI output now. All TVs have got HDMI in them now, so HDMI has become a bigger deal, you know, Blu-ray and so on and so forth, right? What on earth is the point of putting gold plating on there? And I guess some of it comes back to perceived durability, but the durability is actually quite complicated. Gold is a soft metal, but the softness is only relevant when you compare it to what its receptacle is. So if you have two metals, in fact, any two minerals and you scratch one against the other, the age-old question is which one is going to get the scratch on it? So everyone knows that diamonds are the hardest naturally occurring mineral in the world. So if you use diamond and you scratch diamond on glass, it will scratch the glass. The diamond won't get a scratch. So this guy in 1812, a German geologist and mineralogist, a guy called Frederick Mose, M-O-H-S, he created what's become known as Mose Scale of Hardness. And the fact it was done in 1812 had nothing to do with Tchaikovsky's Overture, although I suppose you could argue the cannons were made out of metal and it was sort of about metal, but never mind that anyway. So Mose Scale of Hardness, right? The idea is that each mineral is scratched against each other mineral to figure out which is harder and which is softer. Very rudimentary but that was the whole basis of it. You can then come up with a scale where one is talc, which is what you get talcum powder from, and a 10 is a diamond and everything else in between. Of course I'm not going to spell out what they all are, it's not relevant, but gold is somewhere between two and a half and three based on its level of purity and obviously if it's an alloy thing, numbers change, but in any case between 2.5 and 3. Most sockets are manufactured out of of copper or nickel but there'll be a layer of tin lead solder over the top. Now, I guess they used to be. The problem is of course now lead's bad so they're trying to move away from tin lead. So you know they're moving to different kinds of solder so they're moving away to, let's see we've got copper alloys including bismuth and you've got silver and indium and zinc and all of these different coatings are designed to essentially protect, to provide a good contact point for resistance but also such that when the metals scrape up against each other there's as minimal erosion as possible because every time you insert and remove a plug you are essentially scraping one metal against another. So putting gold on your plug but not having gold in the receptacle it creates a dilemma. Okay well which one is going to wear out? Because one of the two is going to wear out at some point. And the problem is of course that tin-lead solder has a different hardness to let's say if we're using zinc or using silver or indium or whatever else they're using or bismuth whatever they're using what alloys they're using you know to get away from the lead. I mean obviously gold on gold is ideal However, the truth is you don't really know. But if you had to pick one of them to wear out, which one would you sacrifice? And I'd put my hand up and say I'd sacrifice the plug. Because I mean I could always buy another cable. But replacing a socket in a stereo amplifier? I don't know about that. Or a TV set? That'd be bad. Bottom line, the HDMI standard says that you have to have a plug that can support 10,000 cycles, essentially. That's insertion removal cycles. Now, it's pretty common to go for a number of about, I don't know, 2000 in the industrial area that I play in, and that's fine. But in consumer space, there's more of an expectation. That said, how many times have you really inserted and removed your HDMI cable lately? It's not something I do every day. Less than 10? Yeah, exactly. So, I mean, you could argue that this whole discussion about gold being more durable or being, you know, it's a little bit ridiculous. It's like, yeah, well, no one's going to sit there and go plug, unplug, plug, unplug, plug, unplug five times a day, 365 days a year to get to 10,000 after a few years or whatever the hell. They're just not going to do it. In any case, so we'll put that to one side and say, you know what, it probably really doesn't matter. Eventually, it's going to wear out no matter what metal you use on there, either the plug or the socket. But the one thing that gold does do, or rather doesn't do, that most other metals do do, is it doesn't tarnish. So it doesn't oxidize at any decent rate of knots. So that is to say everything eventually will oxidize, however gold takes a long time, very long time, compared to something like aluminium and compared to copper. Because when copper oxidizes of course it goes that horrible green colour and they make roofs out of it and they have a pretty green roof and every time I look at that I'm like oh that's copper that's rusting nice but you know it's it gives to call that green look and it's like that's cool so when I for example when I was in Canada I went over to have a look at at Quebec City and Montreal and they had a whole bunch of buildings there with the copper roofs right so they got that nice green sort of sheen on the roof and it all looks very cool very different. What was the point of that? Oh yeah, that's right, because gold doesn't do that, that means that, well at any decent rate of knots, it means that essentially you'll have beautiful pristine contacts on your connector for a long time. And that is of course until all the insertion and removal cycles scrape off the gold layer and then you're back to whatever's underneath which will corrode and then of course you're kind of screwed. So the gold plating, it's important to realize that it's not actually gold connectors. It's gold plating over the top and it's only a thin layer. So I guess the next thing to sort of get our heads around is just how thick is it? Well, I had a look into this and I found a really good article and there's a link to it in the show notes. It was a technical report by AMP connectors and I've actually used AMP connectors multiple times in my career. In any case, it's called "Golden Rules" which is, yeah, kind of cool, playing words there. "Guidelines for the use of gold on connector contacts". It talks, there's a table in it, it talks about the thickness of the gold plate and how many insertion removal cycles you could expect from such a thickness, which is cool, right? We're looking at for 2000 insert removal cycles, which is what I would expect for most connectors, you're looking at 1.3 microns, which is micrometers, but if you want that in micro inches that's 50 micro inches. That's not a hell of a lot of gold. So then I thought to myself, okay why don't we do some math on this and figure out just how much you would have to put on a HDMI cable? Because they don't publish this, right? I mean I looked and I couldn't find it. I just did some math myself based on a few assumptions. So what we're going to do is we're going to assume that all you need for starters is 1.3 microns. Looking at a standard HDMI cable, a type A cable, which is the full-sized one and all of its dimensions, and a HDMI type A connector, just if anyone's interested in millimeters, is 21.3 wide by 4.55 mil high by 10.9 deep. That's the outer shell, that's the most impressive part. The pins on the inside of course, well yes, I mean they're also going to be coated but you know their area is negligible compared to the outside so we're only going to consider the outside area. We'll assume it's a perfectly rectangular shape, I know it's not, but if you were to actually unwrap it you would probably find the area would be quite comparable to treating it like it's a perfect rectangle. So that's close enough for this sort of estimate anyway. So if you do those, if you crunch those numbers you end up with about 563 square millimetres. If you assume a thickness of 1.3 microns that gives you a total volume of gold of 0.73 cubic millimetres. We take the density of gold that's 19,320 kilos per cubic metre which is you know divide by several thousand whatever you end up with 0.019 grams per cubic millimeter that gives us a total per per plug of 0.014 grams that's not very much so if we then look at the current exchange rate in US dollars that's about $41.34 a gram at least it was yesterday when I checked it so that works out at 58 cents a a connector or a $1.17 if you consider that you've got two connectors on a standard HDMI cable. $1.17 is worth gold on the cable. Now we're going to assume that the thickness is approximately linear-ish. I say approximately linear-ish, but I imagine that as you add layers that it would not be a linear relationship in your wear out mechanism because if you look at the table it tends to suggest that in the AMP technical report. So we're going to quadruple that number, so it's not going to be 1.3 microns now, it'll be four times that. So even if we do that to ensure we get to the 10,000 required by the HDMI spec, we still, and the bottom line is each cable is just about $4.68, round up caught $5 for error. So assume then that going from a HDMI cable without gold on it to one with gold on it costs you an extra five bucks in gold. Here's the thing. Is that less or more than you thought, Ben? That seems a lot less. Because that's the thing. You think about gold, you think gold ingot, gold bar, gold wedding ring. I mean, I weighed my wedding ring just for the hell of it, and it weighs 10 grams. But if you look at the weight of the HDMI cable, it's a tenth of a gram of gold in it. One-tenth of a gram. which is 1/285 of an ounce. It's nothing, practically nothing. And yet they charge how much more for these things? If you look at any shop front retailer, like in Australia, maybe Officeworks. In the US, Best Buy. If you're in Canada, Future Shop. Doesn't matter, pick one. You go in there, it'll be at least $10 more for the gold cables, but it's usually a lot more than that. And I saw price differences when I did the research for this of up to $60 more for the gold cable, but it's five bucks worth of gold. And people think it's more. They just think, "Oh, it's gold. It's got to be expensive," right? They use gold in space, right? Because gold is good, and they use gold to line the inside bay of the McLaren F1. Apparently, they did. - Do they? - Well, I haven't actually looked physically because I've never actually seen one in person, but I saw a documentary on it once and I seem to recall they lined it with gold foil because gold was better at reflecting heat. I actually think it was so that when they lifted the bonnet, well, the engine cover, which is at the back of the car, but you know what I mean, when they lifted that up, it'd look shiny and cool. If you're shelling out $1.25 million for a car, sure, put a bit of gold on it. Why not, right? Yeah, exactly. Tesla should have gold door handles or something. But anyway. Surely that's not what people buying their hi-fis are doing. What's that? Lining their houses with gold foil? Why not? Actually, I can think of a good reason why not. Anyway, but to me, it's crazy, right? The disconnect between what you're paying and what you're actually getting. See, depositing the gold on there is not hard, right? I mean, you could deposit zinc on there or tin on there, it doesn't matter. You plate it with whatever. Electroplating techniques are well and truly understood. You're not going to lose gold in the process. So retailers know by saying, "It's got gold on it," that people will expect to pay more and they do pay more willingly. So that's the gold plating thing and how much gold is in it. So now I want to look at some real-world applications. Okay, so before we go on any further, Ben, I was wondering if you could tell us a little bit about Audible. Sure, John. So Audible is the internet's leading provider of spoken audio entertainment, providing digital versions of tens of thousands of audiobooks for download to your computer, smartphone, and mp3 player. You can listen whenever and wherever you want, just like the the show you're listening to right now. They've got over 150,000 titles to choose from across every possible genre. And right now you can get a free audiobook download when you sign up today. Just go to Again, that's to get your free download. And what should you download? What book would be good? Well, I've been using audible for a number of years and went in and thought about what would be appropriate for listeners to this show and there's a couple that I suggest. One is Eric Ries' The Lean Startup, which if you're interested in how companies can, how startups can function and make decisions in situations of extreme uncertainty, dealing with just huge number of variables, some of the kind of things that we've talked about on Pragmatic, it's a really great book and you know maybe sometimes it gets a little bit heavy on the jargon, a little bit heavy with the marketing speak, but I think ultimately this idea of kind of this validated learning and avoiding vanity metrics, it's been really helpful for me in thinking about running this business and in thinking about businesses and ventures in general. The other one, which I thought would be a really appropriate fit, I just did a search in Audible for pragmatism, which is a philosophy. And there is a great book about John Dewey, who is the father of pragmatism, one of America's leading philosophers. And here's the best thing is this is narrated by Charlton Heston. I don't know how you can go wrong with this book. And this is John Dewey, the giants of philosophy. Anyways, those are just a few of the hundreds of thousands of books you can download with Audible and a couple that I think would be good to use as your free books. So again, go to to get your free audiobook today. And thanks to Audible for sponsoring the show. Thanks for that, Ben. Definitely check it out, guys. So in the real world, what I mean by that is, what's a typical application for this stuff for both of these kinds of cables? So we'll look at each of them independently. Start with the speaker cables though. Unfortunately, power at your amplifier does not equal power at the speakers because obviously the signal's got to be carried on the cable out to the speaker. You're going to lose some power in that because no conductor is a perfect conductor and I'm not talking about superconductors here. So in copper you're going to have a loss. You're going to have resistance, you're going to lose power. How does that work? Why does that happen? well it's Ohm's law. Ohm's law voltage equals current times resistance and the addendum to that is if you want to calculate power you multiply your voltage and your current together so p equals vi. So those two little bits of formula we're going to run some numbers. So let's assume that you're using a 25 watt bookshelf speaker. It's 8 ohms looking at about 14 volts output at the amplifier output works out about 1.75 amps. That gives you over a 10 meter long cable run which is 30 feet which I think is a reasonable kind of number for a normal living room right? It's probably a little bit more than what you need. I mean even if you went up, went through the walls or went through the roof, even if you took the long way around I think 10 meters now 30 feet's probably a reasonable sort of number. Given all those numbers we're looking at, if you use OFC you're looking at 1.5 percent voltage drop which is pretty minimal. If you're using the cheaper figure 8 cable that's 6.8 percent. So there is a difference there but it's less than 10 percent for both of them. I looked long and hard for some conversion figures between wattage and dBs for a given speaker. So sound pressure level that you're actually going to get out of these things. So we'll switch to an 8 watt speaker. Let's say it's got a peak rating of 35 watts. That comes out, well this particular speaker in this example has a sensitivity of 85 dB and that's at 2.83 volts at one meter distance from the actual speaker cone. In other words, at one watt the speaker produces 85 dB. So we're going to work with that now. So if I apply a 6.8% drop to that power reaching the speaker, well where does that leave me? It leaves me with, drum roll please, a 0.3 decibel loss at the speaker. 0.3 dB. That's how much you'd lose if you swapped out your C cable for the cheap stuff, for the standard copper, 0.3 dB. That's nothing, or practically nothing. I mean most sound pressure level meters won't even detect something that small. Now noting of course that dB is not linear, it's a logarithmic scale, and that 3 dB is, you know, the half power, twice power point. In other words, if you are 3 dB above or below a reference point, it will be either if it's above it'll be twice the amount of power if it's below it'll be half the amount of power than your reference point but 0.3 of a dB it's out by a factor of 10. You know you're it's negligible. Okay so that's for an analog signal so the signal to the speaker is an analog signal and that signal is going to be essentially affected by noise but the bottom line is the power is going to diminish based on Ohm's law and therefore you are going to end up with less power at the speakers. However, because it's analog, you can't recover lost information from noise, or perhaps a better way of putting it is you can't regenerate the data. Once you've got noise, you're gone. Why that's important is that if we now talk about HDMI cables, The thing is with HDMI cables, the claim is that the gold reduces the resistance overall. So it reduces the contact resistance in the connectors and that's one of the claims that they make about these gold-plated connectors. Now if you consider the fact that they don't get fouled up with corrosion, that's great. That doesn't actually mean that... I mean if you start from a copper connector that's tin-lead coated, it's not going to be an issue really if it's clean. So let's compare them when they're in their primes of their life rather than the state where one's corroded and the other hasn't. If you consider that to be the case, you've got two cables side by side, one's gold coated, one isn't. Consider that a normal HDMI cable is only three to five meters which is 10 to 16 foot long. That's really long HDMI cables, mostly HDMI cables I've got are, like I said, about 10 feet or less. The loss of voltage from one end to the other is going to be minimal, and if you buy a cable that's 10 feet long, an HDMI cable, it's not gold-plated, it still has to work. Right, I mean, you know what I mean? It's like the voltage is going to get from one end to the other, it's going to have a loss of resistance. If putting gold plating on there actually improves that resistance. It makes no difference. It's digital. HDMI has a whole bunch of different signals on it, but there is some 5 volt logic and there's also I squared C, which is, you know, predominantly is 5 volts, though the newest standard dropped that to 2 volts, I believe, but in any case we're going to assume. I don't have, I looked into the HDMI standard and I couldn't get enough information in the lead up to the show, but if anyone knows the actual voltages, please let me know, but based on the information I have at hand, let's assume everything is 5V logic on a HDMI bus. So they'll set a tolerance and they'll say if it drops any lower than 4.7V or 4.5V, then that is not a logic 1. So long as the voltage doesn't drop below that critical threshold, then it'll recognize it as a 1 or it'll recognize it as a 0, and that's the end of that discussion. In other words, you could drop 0.1, 0.2, 0.3 volts and you would not notice the damn difference because it's digital because you can regenerate the data. Once you know what the data is received, you then retransmit it on and it's refreshed. That's the whole advantage of digital over analog. So noise has nothing to do with it. Sorry, noise can't affect it. The idea is that if gold is actually reducing the resistance, who cares? My three meter long cable without gold and it works just fine. What's the gold giving me? It's not giving me any less, the contact resistance has made no difference. So the thing that gets me about this is that all the gold really does is lots of insertion/removal cycles, it'll probably perform better. And I say probably because honestly it depends on the receptacle. So if the socket is made out of a harder metal than the gold, like anything higher than three, and most of shouldn't be but you know they may well be depending upon what alloys they've used because in the quest to get rid of tin lead solder they've come up with all sorts of different alloys to get rid of the lead and some of them may have slightly higher hardnesses than gold and the people that manufacture the gold plating will say "oh that's fine because no one's going to insert and remove this more than 2 000 times in a lifetime" that's probably true. What was the point? The point is honestly unless you're inserting and removing the damn connectors a lot, it makes no difference. It just doesn't. It's not going to corrode. The other thing is exposure to oxygen. When the connector is actually plugged in, honestly, unless there's moisture around the actual contacts where they actually touch, the dissembler metals touch, honestly, you're not going to get much point corrosion at all. And if you're in a high salinity environment, perhaps, you might get surface corrosion. But where the two physically touch, no oxygen can reach because they're physically touching. So if you have a cable plugged in, you leave it plugged in, it will stay connected generally unless it gets wet because there's no way for the oxygen to get in there. There's no path because it's physically touching. So it's the exposed parts that aren't that would get surface corrosion. All right, so those are some real world applications. but there's still more to say about what actually goes into a good cable. So what does make a good cable? And honestly the problem is that this answer is kind of like saying what makes a good car or what makes a good vehicle. I should rephrase that. Obviously if you're moving house once a week or you're moving other people's... you know, in North America, you guys call them pickup trucks and in Australia, we call them "Utes", you know, short for utility vehicles. Whenever someone finds out you've got a pickup, what do they say? "Hey, can you help me move my sofa, couch, TV, cabinet, whatever?" Yeah, I had some mates at uni that, you know, that they got a ute and it was... they said it was just a change overnight. Suddenly, as soon as people found out they had a ute, it was, "Oh, can we borrow a Ute 4 insert reason here that had nothing to do with them?" Anyway, so I guess it's like that question, is that what makes a good vehicle? It depends on what it's being used for and the same answer is true of the cables. So I've sort of narrowed this down with this OFC and gold plating discussion to two common situations, both to do with audio visual, one an HDMI cable for gold plating and one for speaker wire for audio, for speakers. So if we leave it in those areas, HDMI cable is the most interesting one to look at. So let's look at that. What makes a good HDMI cable? And the first clue is it's not the gold. First of all, you need to have really good shielding because the digital information, obviously, it will get corrupted. So the best way to stop noise getting to it is to have an electromagnetic shield around it, which is, you know, most commonly used would be a braid or a foil. Foils are considered to be be more flimsy, braids are considered to be more flexible, so braiding is generally the preferred approach. Shielding that is bonded to the outside of the connectors, in other words where the connector connects into the socket, that braid is actually connected to the outer shield of that, such that the shielding is therefore continuous and there is no exposed signal wire anywhere. One of the other issues that you come across with shielding cables is the issue of shielding at both ends. Because the problem is if you've got two pieces of equipment and they each have separate power supplies or even if they're coming from the same common source, they'll have different AC to DC converters or DC to DC converters in them, they could have floating grounds, whatever they may have, you can end up with multiple earthing points. This is more of an industrial problem but from a consumer level it's very unusual. But something to be aware of just if anyone's interested is that you should really only ground and earth your shield at one end. So when you plug it into a socket and that socket is grounded within the tv set, let's say well the other end of the other device it shouldn't be grounded because if it is, the shield shouldn't be connected, because if it is and that other device is grounded then you can actually get a current flowing through the shield. I call them, there's such things I call them ground loops and earth loops and that can actually cause a lot of problems with noise and it can actually cause lots of other problems. At a consumer level it's pretty rare for it to be an issue and when you get these connected, these good quality cables, they will have the shield bonded on each end. In any case it's also tricky to figure out if they are or they aren't unless you're going to get out a Stanley knife or a box cutter I should say and strip back the plastic to see if it's actually bonded or not. If you've got a multimeter, the easy way to find out is just to... actually you can't really prove it's a shield, but you could always just bell out the outer shield of each of the plugs to see if you've actually got a direct connection. Anyway, shielding, very, very, very important. So on the issue of flexible cables in OFC then. If you have ultra flexible cables, if you have a requirement that your cables are ultra flexible, then sure OFC style cables will be better for you. Not because they're OFC, but because of the fact that they've got a high strand count. So for example, if you're musician as well, Ben, I'm not really a musician, you're a musician, right? and all of the audio cables that you're going to have up on stage, you know, from your guitar, from your mic to your amplifier, they are all ultra flexible cables. They're usually bigger and heavier and they're very flexible. And that's important because you move around the stage. But the problem is when we're looking at figure eight OFC cable around the house, I don't move my speakers three times a day. I don't wander around the room holding my speaker. So if they're fixed in fixed locations, and of course they're going to be, then why do you need an ultra flexible cable? Because nothing's moving. So it doesn't make sense. You don't actually need ultra flexible cables when it comes to speaker audio. You just don't for the average home stereo installation, which is where most of it is being flogged off. How does this all stack up? Honestly, the problem is that there's no real right or wrong. it's only what is the right thing for the application in question. People all want a simple yes gold-plated connectors or OFC cables are always better or they're always a waste of money, but the truth is that there are some benefits. It's important to recognize where the benefits come from though and honestly it's not possible for me to give a definitive yes or no. However, on balance, I will say that gold plating and OFC are not worth the money for, I would say, the vast majority of consumer applications. Most people don't insert and remove their cables a thousand times. Corrosion resistance is less of an issue with either type of cable, therefore, so the gold doesn't help really that much. I can see gold being helpful if you are in an environment that is highly corrosive. So if you live right next to the ocean, so the air has a very high salinity, if that makes any sense. If you're beside a swimming pool perhaps, then gold may be an advantage. Sure, absolutely. But honestly, that's going to be an unusual situation. Although I will actually confess that one of my in-laws has recently built a pool and and they've got an entertainment area out in the backyard. And the entertainment area is walled on two sides and the other half of it is open. So it's kind of like a detached awning, if that makes any sense. And they've mounted a HDTV out there so they can actually watch TV out there. Now that would be an application right next to a swimming pool where a gold-plated cables might actually be helpful because they would be more corrosion resistant. But to me, it's just weird because it's like, okay, you've got a TV set, and fair enough, it's bolted to the wall, but it's out in the yard and it's not locked up. There's no locking up of it. It just seems strange to me, but more people are doing it. - You have a problem with glare? - I would have thought so too, but actually no. It's funny, maybe it's because there's a lot of trees around there. Maybe they're blocking the sun at certain angles. I suspect at certain time of days, there would be a lot of glare actually. But then again, I could say the same for the TV in my room. I mean, the sun comes into it in the morning and we end up drawing the curtains in order to actually watch the TV because of the glare. But anyway, so that's one application I can think of, but most people aren't doing that. So most people wouldn't be able to justify them. I mean, the other issue then with the resistance is unless your speakers are a hundred meters away or 300 feet away, there's still gonna be no real measurable difference your ears using standard cable versus OFC cable. You're just not going to notice it and unless you're moving cables all around all the time there's no need for you to pay extra money to get ultra flexible OFC cables. And if you're getting a better result with OFC it's got nothing to do with the fact it's OFC, it's got everything to do with the fact this has got a lot of strands in it and that's it. So for the average home user in an average situation, and that includes most audiophiles, they're not worth it. And that's it. If you want to talk more about this you can find John on Twitter @JohnChidji. The same on and you should check out John's site If you'd like to send an email you can send it to [email protected]. I'm Ben Alexander and you can reach me on Twitter @FiatLuxFM. You can follow @PragmaticShow on on Twitter or @Pragmatic on to see show announcements and other related materials. I want to say a final thank you to our sponsor, Audible and Squarespace for sponsoring this episode. Make sure you check them out. Thanks for listening, everyone. Thanks, John. - Thanks, Ben, and thanks everyone for listening too. Cheers. (upbeat music) [Music] (electronic music) [MUSIC] [BLANK_AUDIO]
Duration 56 minutes and 16 seconds Direct Download
Episode Sponsors:
Squarespace: Squarespace is the all-in-one platform that makes it fast and easy to create your own professional website, portfolio, and online store. A better web starts with your website. Visit and use the Coupon Code mars for a free trial and 10% off.

Audible: Audible is the Internet’s leading provider of spoken audio entertainment, providing digital versions of tens of thousands of audiobooks for download to your computer, smartphone and MP3 player. Visit the URL below to get your free Audiobook today! Visit to learn more.

Show Notes

Articles about the show:

Oxygen-Free Copper:

Gold Plating:


Premium supporters have access to high-quality, early released episodes with a full back-catalogues of previous episodes


Ben Alexander

Ben Alexander

Ben created and runs and Fiat Lux

John Chidgey

John Chidgey

John is an Electrical, Instrumentation and Control Systems Engineer, software developer, podcaster, vocal actor and runs TechDistortion and the Engineered Network. John is a Chartered Professional Engineer in both Electrical Engineering and Information, Telecommunications and Electronics Engineering (ITEE) and a semi-regular conference speaker.

John has produced and appeared on many podcasts including Pragmatic and Causality and is available for hire for Vocal Acting or advertising. He has experience and interest in HMI Design, Alarm Management, Cyber-security and Root Cause Analysis.

Described as the David Attenborough of disasters, and a Dreamy Narrator with Great Pipes by the Podfather Adam Curry.

You can find him on the Fediverse and on Twitter.