Copper’s sound

November 17, 2015
 by Paul McGowan

Yesterday’s post on wire gauge sparked a few questions that needed to be asked. The constant pulling of wire through tiny openings, 10, 12, perhaps 20 times to get the wire size you need must have some effect on the wire itself. And the question comes quickly. What impact does all this copper pulling have on the sound of wire, if any?

Talk about opening a hornet’s nest, let me start out by suggesting my evidence is strictly empirical–I have spent a great deal of time listening to different coppers–and can report to you they do make a difference. And, depending on the use, a big one. So, let’s look to see what’s happening.

Copper is a soft metal with high conductivity properties, second only to silver. Internally, most copper is formed from crystals and commonly referred to as polycrystalline (many crystals). Each of the crystals are contained in many small regions called grains and between the grains are boundaries (called grain boundaries). The electricity must pass through these boundaries on its travels. There is another type of copper, called single crystal copper, which is made not from pulling copper through small openings, but by casting it into long strips of the exact diameter needed.

As copper is pulled through these many small openings, the grains are continually deformed, with increasing numbers of boundaries between the grains. The more you mess with the copper, the worse it gets at a microscopic level. And how you pull this wire has much to do with its character as well. For example, there are different types of copper, each depending on the process used: long grain, short grain, pure, impure, oxygenated, oxygen free, etc. Each type has different electrical characteristics that we can measure. But the question at hand is this. Are these differing electrical properties audible?

Here’s what I can tell you from my limited experience. First, what holds true for power cables doesn’t always apply to audio cables, though in general they are close. I have never heard a difference when comparing oxygen free vs. oxygenated copper. I have heard improvements in long grain coppers and in particular single crystal vs. polycrystalline. And, for the record, there’s a definite difference between copper and silver. But, by far the biggest improvements in sound quality come from construction and gauge of wire.

That’s at least my experiences.

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21 comments on “Copper’s sound”

  1. Hallo Paul,
    my experiences are slightly different.
    1st I’ve heard differences between oxygen free copper nd oxygenated copper.
    2nd I’ve heard differences between monocrystal and polycrystal copper as well and I slightly prefer monocrystal.
    3rd I’ve heard differences between copper and silver as well and always prefered copper.
    Not to be misunderstood, I know that silver has slightly better electrical values but if the complete system was connected using copper-cables it sounded – I borrow the term from Harry Pearson – more continuous.
    Maybe it’s because material mixture isn’t good for the sound – I don’t know.

  2. Hi Paul, it’s like all ideas of high-fidelity audio, complex. As Paul indicates S. listening should be done blinded test. For example, copper cable versus plata.Siempre has been said that silver wires improve higher band spectrum (treble), but actually improves the sound? If the walls of my listening room is concrete or brick maybe not, but if gypsum or plaster is probably yes because it is a topic that has a higher absorption of treble versus reflect them in concrete walls.

  3. Paul, I’d like to hear your take on silver cables.

    Most every silver-bearing cable I’ve heard has been bright, many times painfully so.

    Love to hear your experiences.

    1. I’m not intending to speak for Paul, just throwing in my $.02. As stated before, cables are the equalizers of the 21st century. Silver is the best conductor of electricity and more efficient when compared to copper.

      That being said, it was Mark Levinson who introduced silver interconnect cables to the high-end marketplace back in the late 70s. The design application was a very fine stranded silver conductor terminated to a Camac connector. These expensive and very thin cables brought forth a liveliness to the top end of the warm sounding high-current Mark Levinson Electronics when compared to copper conductors.

      Due to the significant cost difference between silver and copper is one of the reason’s why pure silver conductor speaker cables aren’t more commonplace. Early silver interconnect cable construction was generally applied differently than copper. Many high-end copper cables winding and dielectric designs evolved and were more efficient in transporting current and possessed a warmer musical balance. Today, a few cable manufacturers use more sophisticated construction techniques applying silver conductors, but at significant prices.

      This is one reason why many silver interconnect cables applications in audio are to complement large tube amplifiers with massive output transformers and extreme high-current solid state designs.

      Did I mention cables are the equalizers of the 21st century?

  4. I like what Paul says : it’s HIS experience, not the absolute truth.
    Not one of the 2 materials is better than the other.
    It’s all about personal taste, like almost everything in this hobby.
    I prefer silver interconnects.
    For MY ears the soundstage opens up and it’s much more neutral, for me very important.
    NOT overly bright as the “opponents” of silver mostly call it.
    With copper I always hear more coloration; the euphemistic terms here are “warm” or “musical”.
    For power cable I prefer copper (I’ve tried silver). To me it sounds more solid.

  5. I often chide one of my oldest friends whom I went to school with. He says he forgot everything he learned in four years. I remind him it was only almost fifty years ago, he should get his tuition money back. Anyway, I got hit with a lot of stuff including two semesters of material science and I had the good fortune to work with scientists including X-ray crystalographers and crystal growers during my working life.

    As far as I know, you can’t create a monolithic crystal by casting material. They’re grown by a slow process of vapor deposition. The atoms must align perfectly. One physicist in Germany claims to have discovered how to grow perfect monolithic diamonds for his Q bit experiments. That is of course his secret. So, while casting copper wire may form fewer larger grains than drawing wire through a die, annealing will grow the grains breaking down the boundaries and that is a must because as drawing wire causes it to harden and become brittle, you could not draw it multiple times without annealing it because it would break. How do more grain boundaries affect electrical conductivity? From what I gleaned from the Wikipedia article I linked to yesterday it increases resistance. How does that work? What is the mechanism? I don’t know, I’m sure some quantum mechanics physicist somewhere wrote a doctoral or post doctoral thesis about it. Bottom line, if you want lower resistance, use heavier gage wire.

    One technical correction to yesterday’s posting. While it is true that originally gage was determined by the number of draws, today it is determined by the cross sectional area of the conductor. Stranded wire of the same cross sectional area will have a slightly larger diameter than solid wire because of air between the strands. Above 0 gage are 00, 000, and 0000. These four gages are customarily referred to as 1/0, 2/0, 3,0, and 4/0. Larger wire is specified in thousands of circular mils or MCM. They typically vary from about 250 MCM to 2000 MCM. The largest I ever dealt with was 900 MCM. The gage of aluminum wire has the same cross sectional area as copper wire of the same size but its resistance per unit length is higher. For a given ampacity you need heavier gage aluminum.

    Silver may sound brighter than copper due to its having less skin resistance effect.

    On the whole, this subject is of no interest to me. All of the parameters wind up one way or another in the Telegrapher’s equation. Here’s a link explaining wire gage number.

    What’s on tap for tomorrow Paul, the Hall Effect?

    1. Love your reply. By the way I thought skin affect was after a certain voltage or freq.
      But I still
      Love your reply and funny as I own a mess of wires that I cannot hear a difference in. Headphone wires are big on wire add ons Silver multi stand and non pull is of course more expensive noting it’s sonic virtues lol.
      There is even talk of wire having directionality can you imagine.
      I am told or read a Large roll is tested in both directions and the one that sounds better is then used. Funny I can barely keep my guys from using mc ap over mc regular and I cannot imagine how this process is done it makes me laugh.
      But wire is big money in audio

    2. The Telegrapher’s equations may hold little mystery but the practical application of such, at audio, takes some effort. We are keen to differences in the phase of incoming audible signals and getting from point A to B in high current applications without phase distortion turns out to be problematic. Smaller wires do this better but can’t handle the current. Large numbers of small wires, then, lessen the skin effect and total resistance but add capacitive and inductive interactions which add frequency filtering and more phase distortion. Good luck figuring out that one on paper. It takes a lot of listening by the engineer to hone the right design, along with measurement to guide the way. I’m certainly no expert on this but I have a friend who is. Listening…gosh, heresy. ; )

  6. There has been no mention yet of silver extruded over copper. Except for my AC-12 cable feeding the P-5, the rest of my system has all silver / copper cables. I experimented with pure copper and pure silver and none had the sound qualities of the combined metals.

  7. Paul a great topic would be power distribution as your company makes great products in This area. Also better ways to distribute the power in our stystems as in keeping video noise out of our audio sound

  8. I have heard differences between wires and connectors, but that was back when I listened to commercial recordings for hours per day. When I stopped listening to recordings and replaced that with musical instruments in the room I gradually lost the ability to hear fine differences like that because the gross distortions of commercial recordings dominate my perception.

    I had an illuminating experience recently. I was hired to make a recording in Steinway Hall, the Manhattan showroom of the most famous American piano factory. The historical Hall is under demolition and the new Hall under construction, so this was a temporary facility in a former bank with a noisy ventilation system that can’t be shut down. I got the microphones as close as I could to the “Quartet for the End of Time”, but the raw recording was unusable.

    A few years ago my local Audio Engineering Society chapter held a seminar about audio restoration with leading experts in the field, and they had recommended Izotope RX software. I got a copy and ran a number of de-noising algorithms after decimating my raw DSD files at 96K/32 bit floating point. This nearly erased the obnoxious whine, air turbulence, traffic and audience noise but listening to the steep time and frequency filters gave me a headache and a perceptual hangover that lasted at least a day.

    This is confirmation of my theory that audio engineers can’t hear. Mixing and mastering are spatial distortion. Every knob in a studio generates time distortion with relative phase shifts or worse, like these DSP filters that preserve every musical frequency but mangle phase to eliminate non-musical frequencies. “Tonmeisters” and other knob twiddlers take the signal further and further from musical reality by mixing and mastering during the recording process, and people who hear “imaging” from this mashup of spatial information likewise have faulty hearing from listening to recordings more than live music.

    I know a handful of control rooms with monitors with good phase coherence, but most of them still have square meters filled with knobs that generate phase distortion, whether physical or virtual. Even those who fool themselves working on a Sonoma or Pyramix workstations go through decimation and generate phase shift in the DSD output with EQ, dynamic mods and statistical reverb algorithms.

    That is why I spend my money on tickets instead of copper. I use stock power cords and contractor speaker cable left over in construction dumpsters, and I get sound that drops the jaws of musicians, including ones that have heard “high end” systems with four figure cables. Some of them say my speakers are not merely the best, they are the ONLY musical speakers. Interestingly, they do not always sound better than audiophile systems on commercial recordings, because the mixing and mastering is designed to work with the flaws of the audio ecology.

    If there are no live music venues close to you, organize a house concert. I know about a thousand musicians who would love to play for you for less than the cost of a high end cable, and there are more under-employed musicians pretty much everywhere. That will give you a better perspective on musical economics.

  9. By this explanation solid core wire should sound better than stranded of the same gauge since the grains have been “disrupted” far fewer times. At least in theory.

    And thanks to Soundmind for verifying today that stranded wire gauge is determined by the bundled size, not the number of draws. That is what I was trying to verify yesterday with my questions.

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