Know Audio: A Mess Of Cables

We’ve now spent several months in this series journeying through the world of audio, and along the way we’ve looked at the various parts of a Hi-Fi system from the speaker backwards to the source. It’s been an enjoyable ride full of technical detail and examining Hi-Fi myths in equal measure, but now it’s time to descend into one of the simplest yet most controversial areas of audio reproduction. Every audio component, whether digital or analogue, must be connected into whatever system it is part of, and this is the job of audio cables, sometimes referred to as interconnects. They are probably the single component most susceptible to tenuous claims about their performance, with audiophiles prepared to spend vast sums on cables claimed to deliver that extra bit of listening performance. Is there something in it, or are they all the same bits of wire with the expensive ones being a scam? Time to take a look.

What Makes A Nearly Good Cable

In a typical domestic audio system with digital and analogue signals you might expect to find two types of cable, electrical interconnects that could carry either analogue or digital signals, and optical ones for digital signals. We’re here to talk about the electrical cables here as they’re the ones used for analogue signals, so lets start with a little transmission line theory.

A transient plot showing voltage rising over about 50 microseconds
This is what happens when I hook a bike light up to a DC power supply.

Perhaps one of the first electrical circuits you ever constructed had a battery and a flashlight bulb connected with a length of two-core flex. When you touched the wire to the battery terminals the bulb lit up, and when you released it the light was extinguished. It was a DC circuit with two states, off and on, and that’s all there was to it. But if you were to hook up a storage oscilloscope to the wire as you hooked up the bulb you might notice something interesting. Instead of jumping from off to on in an instantaneous transition, in fact the voltage would curve upwards over a few microseconds. The DC circuit suddenly doesn’t look as perfectly bi-state as first thought, so what’s going on?

The voltage curves upwards because the wires and bulb are not perfect. They have a small amount of resistance, inductance, and capacitance, referred to as parasitics, and it’s the interaction between these that causes the voltage to rise over a short time rather than immediately. It’s nearly immediate so it’s fine for a flashlight, but as soon as similar wires are used to carry a signal this parasitic RCL circuit will start to affect it. Early telegraph and telephone engineers faced this problem as their wires stretched hundreds of miles and thus had significant R, C, and L values that gave the effect of a low-pass filter. Their attempts to understand the phenomenon gave rise to what we now refer to as transmission line theory, with which anybody who’s worked with RF should be intimately familiar.

Equivalent circuit of a transmission line, showing the various parasitic components present.
Equivalent circuit of a transmission line, showing the various parasitic components present. Omegatron (CC BY-SA 3.0)

Having said that, an audio interconnect is a transmission line in which consideration should be given to parasitic R, C, and L values, I am now going to turn that entirely on its head and say that within reason the transmission line performace of the interconnect as we’d understand it for radio circuits doesn’t matter much at audio frequencies.  The reason comes down to the short length of an audio interconnect, which at something in the order of a couple of feet (or a meter) has parasitic values that are so tiny as to make little difference as a low pass filter. When this is compared to the wavelength at audio frequencies — 300 km at 1 kHz — it is insignificant.

Going back to our flashlight bulb, the current in those wires from the battery was DC, always flowing in the same direction. If we imagine them as single strand thick copper wires, we can further imagine the current within them as though it was water flow in an idealised plumbing system, with the flow evenly distributed across its cross-section. We know that electrical current creates magnetic fields, so the wires powering our bulb will be surrounded by a static field as long as the DC current flows.

A current density plot across a conductor, it's blue at the edges indicating higher current, and black in the middle indicating not much current.
The skin effect illustrated by a current density plot on a cross section of a conductor. δ refers to the skin depth, in which the majority of the current flows. Biezl, Public domain.

With an AC current such as an audio signal, the magnetic field is different. As the current changes so does the field, and since changing magnetic fields induce currents in nearby conductors it will induce extra currents in the wire. These don’t flow conveniently as linear currents along the conductor’s length, but as circular so-called eddy currents within it. Because part of the circular current flows forward and part backwards, towards the centre of the conductor the eddy currents cancel out the forward current.

This gives rise to the so-called skin effect, in which AC currents flow predominantly towards the outside of a conductor, and harking back to the earlier paragraph this can produce the result of increasing significantly that parasitic resistance at AC audio frequencies. For an audio interconnect this can adversely affect its quality, so it’s usual for audio cables to increase their surface area as much as possible by having many small strands of wire instead of a single larger one. In case that’s not enough, higher quality cables ensure the lowest resistance on the surface of the wire strands by silver- or gold-plating the copper.

Exploding Some Cable Myths

Direction arrows on a piece of speaker cable
Direction arrows on a speaker cable. Richard Corfield, with permission.

So we’ve established that a good audio cable should have minimal parasitic resistance, inductance, and capacitance. Due to its relatively short length its performance as a transmission line in the RF sense is largely irrelevant, and the skin effect can be reduced by using a multi-stranded cable. But there are some other things to consider when buying a decent cable, and they are perhaps the most interesting because here we enter the world of audiophile woo. If you look at cables in an audiophile catalogue you’ll see terms such as “Oxygen-free”, and “directional”, what do they mean?

Oxygen-free copper is a very high-grade form of refined copper. It has a very slightly better conductivity than regular copper because of the removal of impurities, and thus audiophiles claim that it delivers noticeably better quality. The reality is that the length of an audio interconnect is so small that the marginally better conductivity is not significant in its performance. Applications that require longer cables in the order of hundreds of metres could see a benefit so we’d expect to find it in scientific instrumentation for large projects such as CERN, but for short audio interconnects it’s simply a marketing tool.

If you buy a decent interconnect it’ll probably use oxygen-free copper, but its performance will come from using a large cross-section of fine and maybe silver-plated wires and not from the extra-pure copper. Directional cables are another matter, you will find many audio cables with little arrows on them indicating the direction in which the current should flow. A web search will reveal a variety of explanations for this that usually settle upon the parasitic diode action between individual grains in the mass of copper, and some of them even suggest that directionality will grow with use. It makes yet another great marketing tool for gullible audiophiles, but unlike the conductivity of oxygen-free copper it has no basis in truth. Audio cables or indeed any other cables simply are not directional, they work just as well whichever way round they are plugged in. Sorry audiophiles, you’ve been had.

Any Idiot Cable Can Count To One

Gold cables: not what they seem.
Gold USB cables: not what they seem.

So far we’ve only looked at analogue audio cables in this piece, but of course they aren’t the only cables sold to audiophiles. You can buy “special” IEC mains cables at outrageous prices for example, or audiophile quality digital cables for Ethernet, USB, TOSlink, or HDMI.

A mains cable is just a mains cable as long as it has conductors rated for the appropriate current. Digital cables are almost as straightforward.

Along with digital cable myths is one element of truth, but it’s not one that should cost you hundreds of dollars. Digital cables are unlike analogue audio cables in that the bitrate comes at a much higher frequency than that of the signal encoded in the bits. Thus their transmission line performance becomes a significant issue, and occasionally this can show up in a choice of cable.

Find the cheapest sub-$5 HDMI cable on the market and the chances are it’ll work with a 1080p signal but not a 4K one, this is because its transmission line bandwidth isn’t up to the extra demands of 4K bitstreams. But before that $1,000 HDMI cable comes off the shelf, try a $10 one to replace the $2 one, and you might be pleasantly surprised.

Even the cheapest HDMI cable can carry multiple gigabits per second, and laughs at your digital audio bitrate way down in the megabits. And as long as the ones and zeros make it intact to the other end of the cable, there’s no sense in spending more money — there is no such thing as a better sounding one or zero.

There may be some audiophiles reading this piece and becoming irate, because clearly I don’t know what I’m talking about when it comes to directionality or oxygen-free copper, and especially with $1,000 mains leads or Ethernet cables. To them I’ll make this offer: there’s a pint of Old Hooky in an Oxford pub for the first person to prove me wrong. But the standard of proof is quite high, I’ll accept none of that “The oxygen-free gold-plated USB cable gives a rich chocolatey tone to the broader soundstage” mumbo-jumbo. Instead I’ll take side-by-side tests with a high-end professional audio analyser. Let’s see what the Audio Precision says about it, shall we? I hate to deny the most excellent Hook Norton Brewery a sale, but something tells me I won’t be buying that pint any time soon.

We’ll be back with another in this series, and having comprehensively explored the components of a  domestic audio system it’s now time to look at it in another way. How can we measure audio performance?

97 thoughts on “Know Audio: A Mess Of Cables

    1. If we use a common rule of thumb for the simple resistance increase, at the bottom of the linked section of the wiki article, the diameter of a wire at which resistance would increase by 10% at 20kHz is 1.4mm. That’s pretty thick, so I’d say you’re generally right, but for audio one really, really doesn’t want impedance to vary across the frequency range, so I’d want to stay very far below that number. You definitely wouldn’t want to run 18ga solid-core for audio, though.

      https://en.wikipedia.org/wiki/Skin_effect#Resistance

      1. Unless you’re using Litz wire, the strands touch each other and conduct to each other so much that the difference due to skin effect is very tiny.

        More practical considerations with solid versus stranded are: stranded is less likely to fail from being repeatedly bent, solid is easier to use with binding posts and other terminations.

        1. There is an interesting article about audio cables on the audioholics website: https://www.audioholics.com/audio-video-cables/pear-cable-science

          In short:
          The general electrical behavior of speaker cables and amplifier/cable/loudspeaker circuit can be summarized:

          Low impedance is important to speaker cable
          Impedance is dominated by resistance at low frequencies
          Impedance is dominated by inductance at higher frequencies
          Capacitive reactance is insignificant compared overall circuit impedance and will only affect signals that are well over the +100 kHz range
          The article discusses test results obtained from various combinations of amplifier, loudspeaker, and cable types over different cable lengths. I will summarize (note the trend in cable length):

          Cable properties can be shown to affect the impedance interaction of certain amplifier/cable/loudspeaker circuits with 6 meter (19.5 ft) cable lengths
          Esoteric geometries (Litz, bi-metal plating, etc.) only seem to show any significant reduction of skin effect for long cables, over 10 meters (32.8 ft)
          EMI interference is negligible for various 5 meter (16.4 ft) cable designs but become pronounced and varied at 50 meters (164.0 ft)
          Various amplifier class topologies showed different susceptibility to interference on various 28 meter (91.9 ft) cable designs
          High sensitivity speaker drivers are more susceptible to interference
          Different cable construction will behave differently in impedance and noise rejection
          Summarizing what these fellows are saying about cable affects on audio performance:

          Unstable esoteric audiophile amplifiers that are overly sensitive to cable properties are the real culprits
          Any effects from cable properties are so system specific that there is no general solution to improve sound quality with cables
          There will be no difference in properly designed cables below 2 meters (6.7 ft) length irregardless of amplifier/loudspeaker combination
          Using the shortest, lowest impedance cables possible is the only universal way to minimize effects of cable electrical properties

    2. Vaguely related, stranded cable has little to no influence on skin effect. Electrons are free to skip from one strand to another while still running along the surface.

      The correct tool for that job is Litz wire: individually insulated strands woven in a pattern where every strand follows a path that alternates between surface and center.. sort of like twisted pair for overachievers.

    3. Even if skin effect is real, increased impedance (resistance) will only make your music quieter, it won’t affect the shape of the waves.

      PS: James Randi offered a million dollars to anybody who could hear the difference between a $1 zip cable and an audiophile speaker cable in a blind test. Nobody won.

      1. There’s no question that skin effect is real, and frequency dependant attenuation certainly affects the signal in more ways than simply lowering the amplitude. Wether this affects typical audio setups in a distinguishable way is another question..

  1. I don’t know where exactly your probes are, but my hunch is that you’re measuring the bulb’s inrush: while the filament is cold, it has a much lower resistance, so it’ll bring the battery’s voltage to its knees, courtesy of its internal resistance.

    I might be wrong, though :-)

  2. Recently bought a Toslink cable. There were many options in the Bezos Barn for gold-plated connectors. Just a flash of gold on the retainer part of the connector, sometimes the core shield, maybe even some on all or various parts of the backshell, obviously not electrically connected to a darned thing.

    1. It’s a common misconception that gold plating is used to lower the resistance of a conductor (even the author made that mistake). The fact is that gold has a worse conductivity than copper so it wouldn’t improve resistance at all. Gold plating is used on PCBs, cable conductors, and connectors to protect copper from corroding. Plating an optical Toslink cable is definitely a gimmick, but gold plating electrical connectors is likely to prevent a faulty connection due to oxidization over time.

      1. Immersion gold (pure gold) is used instead of HASL (Hot Air Solder Leveling) for PCB to improve flatness when you have huge BGA devices.

        Hard gold plating (Electroplated Nickel Gold) is used on card edge connector for reliable electrical connection. It is harden to handle the wear.

      2. If you’re really looking for low impedance coatings, gold is crap. You need to go with silver. Way better conductor than copper.

        Fun fact – silver is even a great conductor when oxidized. Which is good, because unlike gold, silver will oxidize quickly and thoroughly when exposed to air.

        If you look carefully at *real* professional audio equipment, you’ll often see XLR connectors with horrible black pins. Those are silver coated pins that have oxidized, but they still work really well electrically.

        Than again, try selling grungy, ugly, silver plated connectors to someone to replace their expensive gold versions….

      3. Well close.

        There are a lot of considerations when choosing metals for tasks (metallurgy).

        The skin effect was covered.

        Gold was mentioned in the context of improving conductivity (oddly) as gold is a poor conductor compared to copper.

        So there are the other two consideration which come from the effects of environmental oxygen.

        Oxygen generally doesn’t get to far inside a conductor (just surface oxidization) so it relay doesn’t alter the conductivity of the material itself so the defaults here are (Aluminium / Aluminum – terrible) (gold – not so good) (copper – excellent) and (silver – even better).

        This is all very well until you need to connect to another metal or even perhaps to the same metal. Now you have to consider weather to find a way to remove oxidization permanently for permanent connection or alternatively look at the conductive properties of the oxide for re-connectable surfaces.

        There a whole technology behind this like “self wiping” contacts that wipe away the oxide as the connection is located into position.

        But more generally.

        Gold is a very poor connector and gold oxide isn’t any better so why is it used. Well it’s mostly used on re-connectable surfaces because gold is a better conductor than copper oxide but more importantly – gold is soft so the forces of locating the connector are enough to displace the gold oxide AND often also the oxide from the other metal on a connector designed to do so.

        Silver is a far better conductor than gold so why not use it instead of gold in the above situation. Well silver is very hard so if doesn’t work well with connectors that are designed to wipe away the oxide.

        Where silver is very good is in RF connections. Silver oxide is a very good conductor it works very well in RF especially as the connection of the ground shield of a RF connectors (or simply higher frequencies connections as opposed to DC and perhaps Audio). The natural oxide layer (from environmental oxygen) is very thin also so it doesn’t cause a reduction in conductivity in the “skin effect” range.

        While I am here – the other properties than are often miss understood.

        :Heat sinks: The thermal properties of copper and aluminum. AND the not so often considered properties of their oxides.

        The three properties of concern are
        Thermal conductivity – how fast it will move heat to the rest of the same metal
        Thermal Mass – How much heat it absorbs before it’s temperature is the same as the source of heat.
        Thermal dissipation – How fast and how much heat it can transfer to the air (other mediums not mentioned here).
        A forth issue in complex heat sinks it the thermal transfer at the interface of the two metals but as oxides are removed prior to making this mechanical connection, there or no real considerations here.

        Most heat sinks are Aluminium (Aluminum) as it has high thermal mass and is cheap and aluminum oxide transfers heat to air quite well.
        The downside of Aluminium is that because it’s a poor hear conductor, you get a temperature gradient across the heat sink from the heat source to the extremities where the heat is dissipated, it also needs a relatively high contact surface area with the heat source. Aluminium is a better at storing heat in the short term (until it is disputed) than even copper. So if you have a low heat source that doesn’t rapidly fluctuate in heat generation then Aluminum is a good thing. Aluminium looses it’s edge when the heat source is high as it won’t get the heat from the source to the areas where it is dissipated fast enough or the dissipation isn’t good. So in the end you get a temperature gradient from source to dissipation area and the gradient is wider than the heat source temperature and ambient temperature.

        In electronics the considerations for dissipation from heat sink to air is the same for both Aluminium or Copper. It comes down to surface area. One obvious solution is a bigger heat sink as that would have more surface area.

        A better consideration is the surface at a close up view. Polished surfaces are worst as they are near flat and promote laminar air flow.

        Next, natural surfaces – or oxidized surfaces. This increases effective surface are considerably. However the natural oxidization of copper is thin so it better to chemically oxidize it.

        Another alternative for Aluminum is Anodizing which is very effective at increasing effective surface area.

        So the low down is that copper isn’t much good for heat sinks unless they have a very high dissipation which requires strong oxidization and that’s simple to do for a hacker used to making PCB’s

        Out of time.

        1. This idea of anodizing aluminum heat sinks to increase surface dissipation sounds great. But I think it must be quite a fine process because the importance of cavities geometry. (See below, the link to micrographies of anodized aluminum).

          Anodizing involves firstly to remove entirely the oxide layer and secondly to build a new layer, atoms by atoms, on the surface. The process itself isn’t perfect and the surface is thus uneven. This what we want.
          If you get deep holes, the walls are face to face so they tranfer infrared from wall to wall instead of from wall to air. Then I guess it’s better to get valleys instead of holes. Then it becomes less as a process. It involves process control. If you don’t control well this process, I’m not sure the heat disspiation improvement you’ll get will worth all the troubles doing it. (I won’t tell how much I’d like to see Ben Krasnow having a look at this!)

          https://www.researchgate.net/figure/FESEM-cross-section-micrographs-of-samples-anodized-at-5-mA-cm-2-for-10-minutes-in_fig2_280620925

          (Oh, by the way, can’t resist: I would remove that impossible one:”So in the end you get a temperature gradient from source to dissipation area and the gradient is wider than the heat source temperature and ambient temperature.”. Cheers!)

          1. I want to see someone with the fancy measuring equipment to test some aluminum CPU heat sinks, then glass bead blast the aluminum all over except for the area in contact with the CPU.

            Test again to see what, if any change there is in performance.

            I figure the roughening of the surface should increase surface area and thus increase both radiation and conduction.

            Back in the days of solid ceramic packaged CPUs I filed flat the bottoms of many heat sinks and glass bead blasted them. They were for the most part quite cheaply made for those CPUs, simple aluminum extrusions, often with multiple slots cut at 90 degrees to the fins. PC builders would pile on a ton of compound to try and fill in the gaps.

          2. Forgot to add, what effect on cooling performance does the color of dye used in anodizing have?

            Take several of the same model of aluminum heat sink, glass bead blast to remove the anodizing. Temperature test all of them to be certain of their performance though they ought to be the same. Weighing them all to see how close (or not) they are to the same mass would be another useful data collection.

            Then rig up the lot to simultaneously anodize them, then have individual dye baths to transfer them to. The key thing is to make sure the process conditions are identical for every one.

            Then test again to see how much change (if any) there is from each heat sink’s freshly bead blasted performance. Would have to do at least three of each color to get an average.

            Black is often used on radiators because it is both a good radiating color and a good absorbing color. But the properties of the coating also make a difference. Special coatings were used on copper radiators for vehicles but rarely, if ever, used on aluminum radiators.

        2. Gold is pretty much chemically inactive, so you’ll have to outside of operating environment to have gold oxide.
          You don’t want pure gold for contacts as it is very soft and will wear out very easily.

          Aluminum is cheap, less dense than copper, doesn’t tarnish and you can add color dye during anodization. It is soft and you can extrude aluminum or cold forge easily to make heatsinks. One can make cuts on long fins to break up laminar air flow.

          1. Thanks for the correction on gold my memory of various metal oxidization rates is a bit rusty :)

            One of the problems with Aluminium is that it can’t move a lot of the heat to where it is dissipated very quickly without a large contact surface area with the heat source. That’s why the older Intel heat sinks had a copper slug in contact with the CPU and a much larger surface area of the aluminium in contact with the copper than was possible directly with the CPU.

          2. AMD Zen1 heatsink have evaporation chamber in the core and extruded aluminum exterior. Their high end one uses heatpipe with the usual aluminum fins.
            My friend’s Core2 era PC has heatpipes with copper fins, but that was before the copper went way up. It was mostly for looks and marketing as cooling wise it isn’t better.

          3. @[tekkieneet]

            I had a quad core 3.8MHz from that era. They were very high TPD compared to i3 – i7. It was a low profile case and had what I call the megaphone cooler. Centripetal fan on top of a hollow radial fin heat sync. I couldn’t stand coding on it. As soon as I started to concentrate and picked up pace coding it would start taking off like a jet engine.

            I bought a polished radial copper fin “bowl” heat sink with a normal heatsink fan in the middle of the “bowl”.

            Polished copper is near useless for transferring heat to air so I dissembled the copper fins (made from shape formed cut sheet copper and bolted together at the CPU transfer point) and etched them in PCB etch. Then I put an ultra low noise fan in the middle of it.

            I made a voltage divider and run it from the case fan connector at half speed as that was more than enough even at full CPU load.

            I put an air filter on the outside of the case with a case fan inside and under the filter. The case fan ran from the CPU fan connector so that when the CPU got warmer them it would draw more cool air into the case.

            I never heard the CPU fan but occasionally on a very hot day I could just hear the case fan when the filter was getting clogged.

            The end result was a near silent PC (with a CPU with very high TPD) that never got dusty inside and not needing a clean out. The filter needed cleaning about twice a week as I was in a dusty house close to a busy road.

            I have just cleaned it and I’m going to put it into my i7 desktop.

  3. Every HF-Cable up to xxGhz is specified and very well documentated in any length and all R/X/Z paramters

    But Audio Cable up to 20Khz and a few Meters length is a magic Item, specified by Voodoo Masters to their Resolution, Bandwith enhancement, dimensional performance etc.

    In a few words: Bullshit

      1. I was curious. So used this to work out inductance of a wire:
        https://www.allaboutcircuits.com/tools/parallel-wire-inductance-calculator/

        And this for impedance of an inductor:
        http://www.learningaboutelectronics.com/Articles/Inductor-impedance-calculator.php#answer

        You can then work out the resistive voltage drop as it’s simply a potential divider between the wire and the tweeter impedance (which will likely be more than the DC rating as it too is inductive, so look it up properly). Which gives a voltage drop and can be shoved into this calculator:
        http://www.sengpielaudio.com/calculator-gainloss.htm

        Yeah, in the order of 1 dB. More for tatty old bits of bell wire with really thin conductors.

        Glad my wires are better than bell wire (mains flex) and shorter (2ish m) and I’m 40 (can’t hear much past 14 kHz)

        :)

        Hang on, not so glad about the 14 kHz bit :(

        Chris’ point would show up on an audio analyser. But magic materials wouldn’t solve/reduce it in any reasonable way. Just sensible sized inexpensive cables.

    1. Sometimes “directional” interconnects simply have the shield connected at one end and not at the other. In this way one would be referencing the shield potential to the ground potential of the source component. (Whether this would make any audiblke difference would likely hinge on whether there is a slight ground level mismatch between the two components.)

  4. You do not need a high-end professional audio analyzer for the suggested test. Instead, I would suggest a simple blind test. Many “audiophiles” fail when trying to distinguish (well-encoded) MP3s from CDs, let alone oxygen-free copper cables from “normal” cables. The hard part of the test will be finding an audiophile willing to test ;-)

    BTW: I myself have several good hi-fi systems, tube and transistor amplifiers, really good speakers, etc. But for me it’s the music that counts, not voodoo. Maybe that’s because I’m an engineer.

    And of course: if there is a market where buyers are willing to pay thousands of Euros for sheer nonsense, then there is also an offer. And the snake oil – sellers are not happy with their business exposed. So be careful ;-)

    1. For a current to flow one direction in the cable, there must be a return current that flows the opposite way.
      For AC, you would have current flowing the other way around for the other half of the cycle.

      For a uniform piece of cable any claims for directionality is BS.

      Observation:
      – If the wire is so messed up that it has different transfer characteristics even in low frequency, you really don’t want to use it.
      – If the wire quality is so bad that you have copper oxide in the wire forming a rectifier, then it might let the current go in one direction a bit easier than the other.

      1. It has questionable use as amplifier output is low impedance. That type of shielding is for capacivitely coupled noise which is far more likely at the input side with higher impedance and gain. I would rather have litz twisted pair which at least help to somewhat lower the parasitic inductance of the cable. (Personally I used 25 foot outdoor exterior extension cable back when they wee cheap. These days I use scrap CAT5 pairs in parallel.)

        Also useless for BTL as there is no ground.

  5. I remember audiophiles swearing on rec.audio.tubes or something that they could hear the difference of using a silver plated POWER CORD. So somehow that made the difference, even though there are meters of single conductor power cable in the house and then hundreds of kilometers of various power cables up to the station.

      1. I am sure that someone out there is willing to pay for “clean” power.
        – Clean audio grade holy water in hydroelectric dam
        – Oxygen free, gold plated windings in generator, gold in brushings, audio damping for the generators
        – Audio grade Power transformer in the distribution, substattions
        – Audio grade oxygen free silver wires in transmission lines.

        1. +points for holy water hydro

          I’ve had an oscilloscope and later a UPS explode due to unclean power. But reasonably we should not expect many hundreds of volts spikes on the neutral wire. This was next to a noisy fusion research power supply which was under another group’s control.

          But generally, power should be reasonably clean and it’s fairly trivial to reject noise. Many old amps didn’t really attempt to – my collection of valve guitar amps have very little attempt at filtering much other than mains frequency from the power input. But guitar is all noise anyhow. Especially my playing.

      2. Oddly, I grew up somewhere with clean power. In the heart of the Oxfordshire countryside, we shared the transformer with a village church. Mains transients were not a thing. Useful in terms of QRN for a radio amateur. Didn’t hear any difference in audio.

    1. My dad is one of those silly audiophiles. He isn’t the worst. But he does buy into some of this shit.

      On the power cable, while there was no difference for different cables. There was a difference depending on the neutral/phase connection of the power cables. Most likely some kind of lack of filtering and some 50hz buzz created by a ground loop or something. Not sure.

      When I say, there was a difference, if you listened very well on silent parts, you could hear a difference. Not that one variation was better then the other, just different.

    2. A friends dad works for a power company and they had a work order to install a separate dedicated line with it’s own dedicated power meter for the house owners “magically enhanced audio” equipment with special gold plated IEC 60320 C13 (commonly refereed to as a “kettle lead”) oxygen free copper cables.

      Needless to say that the were asked if there was any way that the power meter could be upgraded to something better with gold or removed all together and what they would need to request for a dedicated line to the power plant. The insanity of audiophiles is truly incomprehensible. Fair play though to the dad, they calmly suggested that they disconnect their equipment from the national grid and use a dedicated generator, then they can do whatever they wanted without a meter. I always picture the audiophile trying to source a diesel generator with gold plated oxygen free copper windings.

        1. Only if the sun is shining at constant strength so the panels have a constant voltage. Otherwise stepup/stepdown is required, nowadays usually done with a switch mode power supply which is most certainly not audiophile-proof.
          But if you’d use a rotary convertor or a mercury arc converter you’d be better off (ignore the transients from switching on and off)

          1. And only when using audio-grade sunshine falling on oxide-free solar panels. You’ll need a name brand solar tracker too otherwise it will sound “off axis”.

          2. The sun light is noisy as hell. Just think that the James Webb telescope has installed shields to keep that light sun light away from the body of the satellite, just because the noise would affect the measurements.

            Fully charged batteries at the nominal supply voltage of the amplifier are the way forward.

            Just need to get hold of the batteries with golden anode and cathode /s

      1. If you were *really* concerned about power, you could always use a motor to drive an alternator to power only that circuit. The only connection to the grid would be a mechanical shaft (charge more money by putting a couple of unnecessary pulleys and belts in between and calling it an “inertial isolator” )

        In fairness, I’ve seen this kind of thing done for powering *extremely* sensitive analog instruments in specialty applications when the local grid was full of horrible loads.

      2. I think you can get what amounts to an “audiophile grade” UPS. Potentially “dirty” power flows in, is used to charge a battery, and then the battery powers an inverter to provide ‘clean’ power to your equipment.
        Whether it will provide a noticeable difference (except to your wallet) I don’t know, but our UPSs at work report when they receive an out-of-spec input voltage/frequency, and it does seem to happen at least once or twice a year. Maybe the biggest use for something like this is just to protect your expensive amplifiers from extreme voltage spikes?

        1. Just get two transformers, step voltage up (or down) then back to your mains voltage.

          Let the hysteresis in the transformer cores cleanup the waves.

          Inverter’s typically produce ugly, approximations of sine waves. First derivate has steps. Computer UPSs are useless, unless atypical ‘online’ models. Which are basically what you describe, UPS and power conditioner in one box.

          The transformers in old school audio equipment used to do this for you, switching power supplies in newer gear, not so much.

  6. Directional cable with diodes in the molecules? Hmm… So the voltage is supposed to flow in a certain direction? Always thought that audio was alternating voltage/current/power. Are they talking about if you apply a positive voltage and it flows to a load and that is the directionality? We do know that current (which is really the only flow in electricity) consists of electrons moving from a source of electrons to where it’s going. And electrons are negative. Power flow based on positive voltage is just a little fiction we tell ourselves to make us comfortable with car wiring and perpetuating legacy schematics.
    Whole thing is nonsense anyway.

  7. And how many have seen or heard of the Audio Brick? A cube of lead wrapped in beautifully finished rosewood. To be sat on ouput transformers to “absorb” spurious mag fields to avoid distortion caused by coupling to cables and other circuitry. And let’s not forget outlet gaskets that prevent acoustic distortion by not allowing sound waves to exit around the outlets in the walls.

    1. Strangely enough I have an audio device with a buzzy transformer, and when the screws holding it down worked lose the whole unit buzzed. A lead brick would’ve fixed that right quick.

      Though so did my Philips #2.

    2. Actually I bet your average sheetrock wall has all *kinds* of fucked up resonant modes and reflection behaviors, and it’d be a lot easier for me to believe that outlet gaskets had done something a human could hear that gold plating had.

      And I’m *sure* that to control acoustic effects anywhere near as small as most of the stuff they’re claiming matters for the cables, you’d have to tear down the entire building and rebuild it from scratch…

  8. Well, those arrows in the cable tell the electrons which way to run. Otherwise, some of them would try go go the other way, causing traffic jams. Picture the effect of all of those angry electrons on the audio colors,. :)

  9. In the days of *big* woofers, there was rarely reason to use anything above 16ga wire to the speakers. The amplifiers however needed rich chunky DC amps. Early enthusiast DIY systems frequently had entertaining effects from cheap cabling and especially connectors on the power side.

  10. I had an inverter power supply that ran at 6 KHz, and some inductors were running hot at 100 KW output. they were made of 1 inch water pipe. I switched to the equivalent Litz wire and they ran cool after that. So sometimes it makes a difference. For speaker cables, just crank up the tweeter a bit. I use mostly #20 intercom wire because I have a big reel of it. I’m cheap, don’t have high bass requirements, and don’t have golden ears.

  11. at the microscopic level,copper wire has a herring bone like surface that is directional,this is likely a manufactuting articfact
    from drawing the wire,this may be the source of directional resistance,imagined or real.as to clean power,ditch the mains
    and go DC all the way,big BIG,supper caps and big batteries to
    keep them full.
    on another note,there are all kinds of ways to build budget
    audio systems,old unused fireplace and chimney?brick up the top
    and any other openings and install a sub into the fireplace,tune
    by “adjusting”the internal volume,very rigid enclosure.
    or fill heavy duty speaker cones with lead shot and epoxy and bolt directly to the wall ,or a wooden chair for the person who cant get enough base,like base players.

    1. like the bass thumpers you can buy to screw to your sofa, which don’t have much of a baffle but just a very heavy cone.
      I’ve bought two second hand bass speakers and mounted them to my sofa (with a low-pass filtered signal into the amp), so that when there is bass, the sofa shakes.
      It is surprising how much louder it makes it seem that the bass SOUND level is, even though it doesn’t generate that much sound – just vibration.

  12. Friend of mine worked for an audiophile manufacturer. As well as overpriced and deliberately pretentious amps, they took standard twin core mains cable, put a braided fabric sheath on it, and sold it for £100/m as speaker wire.
    Their customers swore they were awesome.

  13. You guys didn’t mention it cryogenically treated cables. Once they’re out of deep freeze magic happens. Touched by Almighty…
    Oh, how about cryo vacuum tubes… Brother…sshh.

  14. Thank you. Like a handful of folks here, I’m an engineer first and an “audiophile” (hate the term, love the music) second. The notion that the cables between your gear, at distances measured in feet, is ridiculous – yet people I consort with on the high-fi whathaveyou straight-up refuse to listen to logic when it comes to cabling (which is amazing, as many of them could build you a perfectly matched pair of monoblock amps without so much as looking at a schematic).

    Thousands of dollars… for copper wire (ok, a lot of folks will use 61-strand 5-9s purity silver – no doubt a better conductor, but sonically indistinguishable). You forgot to mention the next level up from OFC cables: the OCC and UPOCC… Paltry OFC only gets you down to an impurity level of 10 ppm (with standard hot molten copper poured into a cold mold introduces as much as 500ppm)… Ohno Continuous Cast (OCC) and the “Ultra Pure” prefix of UP-OCC (quite literally the same f’in thing, btw – but more acronymity == much more better in the hifi world) takes it a step further: casting and extruding the hot copper with hot molds, and cools it later – cutting your 10ppm down to 5. Congratulations snake oil salesmen, you’ve found your endgame. OCC is marketed as being “truly unidirectional” due to the casting process (not really – sane people use diodes to ensure directionality), and easily costs 4X what OFC wire will cost you. Put a core of cotton in, coat some thin strands into Litz wire, braid 4-8 Teflon coated litz wires – and you too can be a cable snob (many cheap USB cables use litz wire, all that means to me is I need to break out the solder pot).

    This is right up there with the ridiculous grade of lubricant the keyboard people (Sorry K.P. – love your column) slather on 2-7u plastic stabilizer posts (krytox 205g0 if you are curious and want to spend a fortune on what is essentially dielectric grease) – or the recording-studio grade sound dampening foam between the PCB and the keyboard case…

    Both groups doing justifying equally asinine behaviors that do little more than throw away money… yet in the quest for a better sound.

    Funny, too, that most audiophiles are no younger than 50. By 35, most people have lost the ability to hear significant parts of the audible spectrum – let alone hear the microphonic differences of their cables, if there even were any. Buy better speakers or a better amp… or, stop kidding yourselves and spend your money on a better hearing aid or reversing the aging process.

  15. Fun article (said the broadcast engineer). But, check your math @JennyList. The wavelength of a 1kHz sound is ~ 1 foot ( or ~.3 meters) [“wavelength at audio frequencies — 300 km at 1 kHz — it is insignificant.” ].

    Though, I think you’re correct that parasitics introduce minimal artifacts (coloration) on line level analog audio on short runs (certainly under 10m).

    I would have liked to have seen some discussion of shielding. A wire’s worth is as much about its shielding as it is about primary electrical considerations. And with the consideration of shielding, there should be some mention of audio levels. Line level vs mic level, vs “phono” (both high impedance and pre-emphasized therefore in need of filtering to remove RIAA curve). Balanced vs. unbalanced is a whole other fun topic.

    But, yeah – directional and oxygen free audio wire are fetishized notions. Give me a decent wire gauge with good quality shielding (against RF or AC induction) and make it flexible enough to have good hand feel and wire management characteristics.

    Thanks for an interesting series. Muppets like us enjoyed it.

    1. RF engineer vs audio engineer? Jenny was talking about the wavelength of a 1 kHz electrical signal in wire — travelling at the speed of light, plus or minus. Her math checks out.

      You’re thinking speed of sound in free air, so you get to divide by a million, roughly. Your math checks out as well.

    2. Elliot made my point on the maths.

      Shielding is an interesting point. I’d suggest that it’s not necessarily such a big deal for line level audio, indeed I have a friend who swore by twisted pair for his interconnects.

  16. Everybody calls stuff they don’t understand “snake oil”, and it’s kind of a mistake in the high end audio market. Snake oil is the preferred suspension media for high-end tweeter frames. It is used to fill the struts that mechanically isolate the speaker from the cabinet, ensuring the only hiss you get is that which was on the original recording.

    And despite what the so-called audiophiles say, you only have to replace it annually, not quarterly. Snake oil doesn’t break down as fast as the other common organic oils (cod or shark liver oil is what most manufacturers recommend,) so it retains its useful viscosity for up to several years. It’s absolutely a good idea to replace it before it degrades, but since it’s only slightly more expensive than fish oils (at $16.00/ounce) when you change it annually it’s actually a bargain.

    The only problem with snake oil is that since it is an organic oil, it is susceptible to bacterial infection. An infected cylinder doesn’t really affect the sound, but the oil tends to give off a foul odor if you let it sit around too long. Some people have tried smearing vaseline around the exposed ends of the inner cylinders to seal the oil so it won’t stink, but I think that can affect the sound and I wouldn’t recommend it.

    Oh, and be sure to get a good quality measuring syringe to change the oil. Being off by more than a few mL can affect the travel of the struts, and that either leaves a mess on the shelf, or raspy highs.

  17. @Jenny “List said: Perhaps one of the first electrical circuits you ever constructed had a battery and a flashlight bulb connected with a length of two-core flex… Instead of jumping from off to on in an instantaneous transition, in fact the voltage would curve upwards over a few microseconds. The DC circuit suddenly doesn’t look as perfectly bi-state as first thought, so what’s going on? The voltage curves upwards because the wires and bulb are not perfect. They have a small amount of resistance, inductance, and capacitance, referred to as parasitics, and it’s the interaction between these that causes the voltage to rise over a short time rather than immediately. It’s nearly immediate so it’s fine for a flashlight, but as soon as similar wires are used to carry a signal this parasitic RCL circuit will start to affect it.”

    The slow turn-on likely has far more to with the fact that the bulb’s filament takes time to heat up with increasing resistance on its way to incandescence [1], not so much the lumped elements in the transmission line equivalent circuit (unless you model the equivalent series resistance as a complex function in time). Maybe try the same experiment today with a LED instead of a flashlight bulb and compare the results.

    A series of posts in [2] calculates skin effect in audio cables through 20KHz and compares the effect against the Fletcher & Munson Psychoacoustic Curves (a.k.a. Equal Loudness Contours) [3]. Their conclusion: “The bottom line is Skin Effect is not a relevant factor of concern when choosing / designing high performance loudspeaker cables for hifi audio systems. The DC resistance and inductance of the cable are far more important factors…”

    If someone is obsessed with skin effect at human audio frequencies, then a cable made up of multiple thin strands of individually insulated wires is better; even how the strands are woven matters. This type of wire is called Litz Wire [4]. ‘The term “Litz” is derived from the German “litzendraht” meaning woven wire.'[5]

    * References:

    1. Incandescent Bulbs, Current, and Resistance

    https://www.eeweb.com/incandescent-bulbs-current-and-resistance/

    2. Skin Effect in Speaker Cables – Conclusion

    https://www.audioholics.com/audio-video-cables/skin-effect-relevance-in-speaker-cables/skin-effect-relevance-in-speaker-cables-page-3

    3. Equal-Loudness Contour

    https://en.wikipedia.org/wiki/Equal-loudness_contour

    4. Litz Wire

    https://en.wikipedia.org/wiki/Litz_wire

    5. MWS Wire Industries – Litz Wire

    https://mwswire.com/specialty-wire/litz-wire/

  18. @Jenny List

    [sorry: my threading doesn’t work; perhaps it’s my browser eating the cookies or -worse- the javascript. Bad browser, bad :) ]

    Absolutely.

    More on topic: I long time ago worked for someone marketing that stuff. Silver plated loudspeaker cables (better conductor). More expensive gold-plated cables (no, not the terminals).

    They did look gorgeous, somehow (needless to say, the insulator was transparent: you gotta see what you paid so much for. Especially your guests gotta see — I think that’s what it’s about, after all. I call that the Apple Asset).

    I was in my physics studies back then. You should have seen the face of this guy when I told him that gold is a worse electrical conductor than copper. That, for connectors, it’s OK, because it doesn’t oxidise, but for cables… not so much.

    It must’ve been late 70ies, at most early 80ies. You had all that OFC talk back then, too. Snake oil is old indeed.

  19. The “directional” cable thing does have a reason to exist, though – to make sure all of your speakers are in-phase and not 180 degrees out of phase from each other. It’s not about the direction of the electricity mattering, though. It’s about making sure the speakers are all mechanically pushing out or in together, all matching up their “out”s to the peak of the waveform and “in”s to the valley of the waveform. Electrically, it’s AC anyway – they could all be hooked up backwards as long as they match.

    1. I think you are mixing up polarity and direction here. The real reason some audio unbalanced cables (not speaker cables) are directional has to do with the shielding. Often unbalanced analog coaxial cables only connect the shield on one end. this eliminates the potential for ground loops when connecting multiple pieces of equipment which also have a chassis grounded power supply.

      1. Yes, I think you’re right. I was looking at that picture on my phone when I wrote that comment and thought the wires were labelled + and – instead of two arrows pointing the same direction. Looking at it now I can see the absurdity of a directional unshielded cable exhibited in that picture. I thought the confusion was about thinking polarity doesn’t matter for speakers.

  20. ” so we’d expect to find it in scientific instrumentation for large projects such as CERN”
    I work at CERN, and at LHCb we actually evaluated using litz wires to minimize inductance in the supply wires of a system that needs to powered by a remote regulator. You really nailed it!

  21. The final test of all the data from the article is notoriously subjective. It’s EARS!
    Any cable will color sound to a degree. How we interpret that color is what makes for unpleasing or pleasing audio. Some guys want the sound as close to FLAT as possible, some less so.

  22. “Golden ear” audiophiles are hilarious. When I saw a beautifully made and very expensive rack mount “Power conditioner” in an audio store a few years ago, I had to smile. We certainly can’t depend upon just that excellent power supply regulation and filtering in your expensive preamp and amp, can we now?

    Somewhere on the intertubes there is at least one test which destroys the “Monster Cable” myth for typical length home speaker cable runs. IIRC, it’s cable impedance affecting the speaker’s damping factor that causes any audible problems.

    And on the ability to hear amp crossover distortion, see the article here staring on page 72:

    https://worldradiohistory.com/Archive-All-Audio/Archive-HiFI-Stereo/70s/HiFi-Stereo-Review-1973-05.pdf

    1. Monster cables are still in my local hi-fi stores, so there must still be idiots willing to buy them. This is also the same store that told me I wouldn’t find a passive USB-C to 3.5mm audio adaptor for under $50 though…

      1. You can’t “beat” a salesperson! Audiophile or otherwise.

        I was looking for a “TV” antenna when analogue VHF had been abandoned and we still had analogue UHF and also the new digital UHF.

        A salesman tried to sell me a longer range combination VHF/UHF “Digital Ready” antenna. I explained to him that I was an electronic engineer and there was a signal strength disadvantage of purchasing a dual band antenna and there wasn’t really anything like a “digital” antenna as the signal is still analogue through the air so I would be fine with the medium gain single band UHF non-digital-ready antenna on the wall right beside the one he suggested I buy.

        He wouldn’t sell the one I wanted and insisted I buy the “digital-ready” antenna. Anyway, I just walked out.

        So , really , most audiophiles aren’t electronics technicians or engineers so are we picking on them after they have already been abused (including financially) by sales people.

        Now I know that I can’t bundle them all into one group. Some strongly support ridiculous ideas that are easily scientifically dis-proven but if that’s how they like their music to sound to them, then why argue with them.

        Then there are some that go to great lengths to achieve actual high fidelity and claim to “hear” a difference that I can’t hear. Perhaps they can, my ears aren’t perfect and like color where one person in many thousands can discern colors that others can’t, perhaps there are those with “exceptional” hearing ability, but once again, why argue with them if that’s how they like to hear their music?

        Now this is just food for thought …

        I think that it’s interesting that people that have developed an increased interest in music (probably from an early age) have the financial resources to spend money on things that many others see as ridiculous and a waste of money. Perhaps theirs a better connection there between “music appreciation” and achieved financial status that is worth exploring.

        Then some may suggest they audiophiles are, well, odd on some way and although that doesn’t seem to fit with the paragraph above, consider that a disproportionately high percentage of CEO’s are psychopathic, that doesn’t mean they kill people like in the movies, it just means they are ignorant to human suffering in the pursuit of their own objectives (which in some way include the corporate they run).

        I think there is a lot we could learn about audiophiles if we weren’t so fixated on arguing with them. Maybe it’s too late now that we have a generation that doesn’t even know there is much higher sound reproduction quality than MP3’s.

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