Is a Copper Conductor Directional?

[Shaddersx]

TL;DR Summary

Request for confirmation whether pure copper conductors are directional - such that there is difference in behaviour depending on which direction the voltage is applied.

Hi,
A question has arisen an a hifi forum (sorry) that cables can be directional. I dispute this, as the proposed mechanism is diodes in the crystal structure etc. or the drawing process to crate the strands.

Assume that it is 99.9% pure copper (CW004A (was C101)) and forms part of a cable with strands.

The proposal is that there is a difference in electrical conductivity from one current flow to the opposite direction current flow, in the conductor. This difference can then be heard, such that placing the cable between the amplifier to speaker produces a specific sound, and then reversing the cable presents a different sound, albeit subtle changes.

Sine wave is a assumed. For positive going voltages along the cable the current flows to the speaker on the positive wire (classic current flow assumed), and on the negative going voltage the current flows in the opposite direction on the positive wire - if it is directional, then one of the signals will be affected - assume the negative going signal

Reversing the cable, means that the positive signal is affected and the negative one is not.

I have searched on this proposed issue - but i can locate no scientific papers etc.

Sorry if i am wasting peoples time - but if there a known effect then it would be nice to know. Thanks.

Regards,
Shaddersx.

 

[DaveE]

No. Just No.
99.999% of the electrical engineering content you find in audiophile sites is BS. It is a community composed of people that think they should pay for Rhodium plated connectors.

 

[Dale]

I agree. Copper is pretty isotropic.

 

[Shaddersx]

Hi All,
Many thanks for the replies - you confirmed what i thought.
Regards,
Shaddersx.

 

[ZapperZ]

All of the claim of any kind of anisotropy in the conductivity need to explain why the https://watermark.silverchair.com/16-3-222.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAjowggI2BgkqhkiG9w0BBwagggInMIICIwIBADCCAhwGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMmHv2LPeWlc2S5cT3AgEQgIIB7ePJsPfsJq4Bz6YRdG6aqyP1gIAFjskUWVCtbYlEzZNO3onkGdt6x5UtutNFD1R_wyN4ytuTvqAtKdQfvFf_Wk4FkZxvoV0ztJK9PLtEMzZq1IBP_pbxNF51cDgj5yCp_FCfw6vQEekmEMoQ1Np26S21597KsQ2VSErV5YqTAQpulKzsoCKbEY-DZMs_8spEirahr5xWUc1bDvn0nq4AB5JuhDcDt3eMJdLMunhL1q3CqaKvju3GQlIV2O9RWpoYnqxPJKZWAJhTuyI-ZCyht8yAP3HqeNZ414SWE1ZWOunpreypo09KC0_1krgCECOG86FoZxIbzgDMl77Vlp2VpauFiLEIul6mJhds217m8BNs_dMkMJdgdETLpH1uD6wwVxhKJDOZMN2OATmMjq5QnDEOVa1ScoOy55dixyPajf5AFNQcnQG3KDe_Qs9YAAZqhRX0beEgMH7nkxoqTj1gM0IAkQwORz4tGHdZgMhZ9m0BxdGsS1k9pDJ9UL84ukHFVeYz1cfDDo_6wOVK7zHg0MAHz4mit9HzGe28xk5UB3HP8SHQEPl7AOk6Kh6_F5zUsLo0M5WG648M1S27NqCrVEYF8cp2yJ_cT7QCwBUNIo45rg6QsaevDBQsRUb6TwrzfqZ15811hS9itD7cin4 shows no such anisotropy. After all, this is the microscopic detail of the bands that make up metallic copper.

Zz.

 

[gleem]

Could the presence of oxides on the connector pins or poor solder connections especially on cheap cables cause problems? Just a thought.

 

[Shaddersx]

Could the presence of oxides on the connector pins or poor solder connections especially on cheap cables cause problems? Just a thought.

Hi,
This may be a possibility, but the people are discussing new cables just terminated etc., so i think that this is not the case. The cables they are talking about will have arrows on them for the direction to be used.
Thanks for the reply, and to all others too.
Regards,
Shaddersx.

 

[gleem]

he cables they are talking about will have arrows on them for the direction to be used.

Is that true? The manufacturers are saying that there is a preferred direction? So what do they know that we don't?

 

[Shaddersx]

Is that true? The manufacturers are saying that there is a preferred direction? So what do they know that we don't?

Hi,
Yes - the cable manufacturers put arrows on the cable. If you examine hifi cables from vendors - there is a lot of suggestion, but no explanation.

They know nothing more than anyone else - it is what hifi is about, suggestion and placebo effect. Here is an example :
https://www.nordost.com/faqs-directionality.php
I must apologise for polluting this forum with such information.

Thanks for replying.
Regards,
Shaddersx.

 

[Dale]

Here is an example :

Very interesting. They specifically indicate that they do not manufacture any asymmetry. They describe it as a "wear" phenomenon. So the arrows are there to indicate which direction the "wear" is in.

You don't get a diode simply by oxidizing a metal. Diodes are semiconductors with very specific doping on different sides of the semiconductor. I don't see that happening. You simply don't get gallium arsenide by playing your stereo loudly. I am not sure what materials they think you do get to produce this magical diode effect.

If I were a cable manufacturer here is what I would do: Produce a line of "bi-directional" cables with arrows pointing both directions, do a simple consumer preference test to show that the cables perform equally well in either direction, then smear my competition for making inferior connections that produce these diode byproducts (of course, without measuring it but just taking their marketing message's word for it). I could even certify my conductor connections to be completely gallium arsenide free.

 

[DaveE]

The arrows are only there to convince people to buy more expensive cables. It is 100% marketing. Technical questions are irrelevant in this case.

I've designed and worked with electronic cables in satellites, tracking antenna systems, lasers, semiconductor manufacturing; all pretty high-tech equipment. NO ONE in these industries does this or even considers it. If you called up the wire and cable suppliers to ask about this first they wouldn't understand your question, then they would either laugh at you or talk to you like you were 12 years old. OK that's not true, they would instantly understand that you are a marketing guy who is only interested in what the outside of the cable should look like and they would make it however you wanted.

No. Just No. It's not a thing. It doesn't happen. No.

 

[boneh3ad]

No. Just No.
99.999% of the electrical engineering content you find in audiophile sites is BS. It is a community composed of people that think they should pay for Rhodium plated connectors.

While we are at it, I should also mention that audiophiles in general have effectively zero grasp on signals processing, specifically the Nyquist frequency and its implications. All of this high-resolution audio BS pilfered by people like Neil Young is pure snake oil.

I could even certify my conductor connections to be completely gallium arsenide free.

It will appeal to audiophiles as well as folks who want all-natural products free of toxins. Arsenic bad!

 

[boneh3ad]

Hi,
Yes - the cable manufacturers put arrows on the cable. If you examine hifi cables from vendors - there is a lot of suggestion, but no explanation.

They know nothing more than anyone else - it is what hifi is about, suggestion and placebo effect. Here is an example :
https://www.nordost.com/faqs-directionality.php
I must apologise for polluting this forum with such information.

Thanks for replying.
Regards,
Shaddersx.

At least this manufacturer, at the very beginning, suggests a plausible explanation based on the idea that the shielding is only grounded at one end. That could legitimately make a difference. However, they then rapidly return to their homes in into Charlatanville.

 

[Shaddersx]

Hi,
I understand how exasperating and frustrating it is trying to discuss the science behind it. Chord who make excellent DAC's also sell cables with their directional statement a follows :

Almost all speaker cables, in fact almost all audio cables, be they for digital or analogue are, in our experience, directional in that the sound will be better with the cable connected in a specific direction. Chord speaker cables should be connected so that the print on the cable reads in the direction of the signal. In effect, the C of Chord should be nearest the amplifier. The fact the cables are directional is a subject of much debate but our experience is that these differences range from slight to quite marked. One of the main areas that can be affected by the direction of the cable is timing and coherence. With the cable connected in the correct direction the sound will be more articulate and involving

There is a problem when a manufacturer of excellent hardware makes such statements. Hifi is a religion for some, so it is hard to convince people who hear things.

Thanks to all for the responses.
Regards,
Shaddersx.

 

[boneh3ad]

Hi,
I understand how exasperating and frustrating it is trying to discuss the science behind it. Chord who make excellent DAC's also sell cables with their directional statement a follows :

Almost all speaker cables, in fact almost all audio cables, be they for digital or analogue are, in our experience, directional in that the sound will be better with the cable connected in a specific direction. Chord speaker cables should be connected so that the print on the cable reads in the direction of the signal. In effect, the C of Chord should be nearest the amplifier. The fact the cables are directional is a subject of much debate but our experience is that these differences range from slight to quite marked. One of the main areas that can be affected by the direction of the cable is timing and coherence. With the cable connected in the correct direction the sound will be more articulate and involving

There is a problem when a manufacturer of excellent hardware makes such statements. Hifi is a religion for some, so it is had to convince people who hear things.

Thanks to all for the responses.
Regards,
Shaddersx.

This claim is even more laughable when talking about digital transmission. Noise is almost irrelevant in those cases since the data is encoded simply as zeros and ones. For example, an HDMI signal typically has a supply voltage, $V_{cc}$, of about 5 V. If the signal value is greater than about $0.55V_{cc}$, then the receiver reads a 1, and if it is less than that, the receiver reads a 0. The HDMI signal can therefore experience a great deal of signal noise while still transmitting a pristine bitstream.

 

[DaveE]

Hifi is a religion for some, so it is hard to convince people who hear things.

Yes absolutely true.
I actually think that there are some peripherally related cabling questions that are interesting. Things like distortion effects from connector corrosion, triboelectric effects, proper shielding and grounding of signals between electronic equipment, which connector platings or insulation are most cost effective for different applications...
However, I would never talk about any of this stuff with these people; it's pointless, a huge waste of time.

 

[anorlunda]

Here is an example :

The example says=

When cables are manufactured they do not have any directionality. However, as they break in, they acquire directionality.

Although the cable signal is an alternating current, small impurities in the conductor act as diodes allowing signal flow to be better in one direction over time. This effect is also called quantum tunneling, which has been observed in experiments over 25 years ago. Regardless of the purity of the metal used, there are still diode effects in all conductors. In addition, the insulation material will change when it is subjected to an electrical field.

That's nonsense.

 

[gmax137]

Remember the letters in The Absolute Sound, from the reader who said her system sounded better in the dark? As I recall, she could reproduce the objectionable effect by pointing her flashlight at the speakers.

 

[anorlunda]

I presume those audio companies must have some engineers employed. How do those engineers reconcile the marketing claims with the code of ethics?

 

[gleem]

Don"t you follow Dilbert? There is a lot of truth behind those comics.

 

[davenn]

How do those engineers reconcile the marketing claims with the code of ethics?

what ethics ?? hahaha

 

[DaveE]

I presume those audio companies must have some engineers employed. How do those engineers reconcile the marketing claims with the code of ethics?

That depends on how you define "engineer". Some are really just sales and marketing with purchasing people who deal with suppliers that do everything else. The ones that hire engineers mostly have manufacturing and test engineers, not design engineers. There are a lot of people with "engineering" jobs that have never been exposed to technically difficult designs where the ultimate judgement is "did it work" not "do your bosses like you". I feel very fortunate that my first job was in aerospace R&D where BS isn't part of the equation. You really can get started down the wrong path in EE.
BTW, "code of ethics" is mostly about independent contractors, PEs, consulting and such. At a company like Intel or Boeing that's just not stressed in product development; there are many other requirements, like industry standards, but you are just a small part of big diverse team with a bunch of different specialists.

 

[berkeman]

BTW, "code of ethics" is mostly about independent contractors, PEs, consulting and such. At a company like Intel or Boeing that's just not stressed in product development; there are many other requirements, like industry standards, but you are just a small part of big diverse team with a bunch of different specialists.

At the company where I work, we all have to sign a Code of Conduct (including a section on ethics) every year. Even us engineers...

 

[gmax137]

Customer on Phone with Service Rep: "Hey, I just spent $1000 on these new speaker cables and they don't sound any better than the lamp cord I have been using..."
Service Rep: "Hmm, are you sure you have them oriented correctly?"
Customer: "What?"
Service Rep: "They have to be oriented correctly: The arrow must be pointing towards the speaker."
Customer: "Wait, let me try that. ... Wow, you're right! I can hear a difference. The sound is more articulate and involving..."

The point is, people want to hear an improvement. The audio companies just give them what they want. If you think the $1000 cables sound better, wait until you audition your buddy's system, he bought the $2000 cables (the gallium arsenide-free version).

 

[cosmik debris]

The only truly directional cables I've seen are some guitar signal cables, they have a connector at the guitar end that shorts the cable so that you don't get that awful buzz/crash when you plug it in. They have directional arrows on them but it isn't for signal flow.

Cheers

 

[DaveE]

The only truly directional cables I've seen are some guitar signal cables, they have a connector at the guitar end that shorts the cable so that you don't get that awful buzz/crash when you plug it in. They have directional arrows on them but it isn't for signal flow.

Cheers

Yes, there are lots of examples of that sort of design. Loop-backs, interlocks, different shield terminations and such. But those are asymmetrical circuits not directional current flow through copper. In good designs you can't plug those in backwards, the connectors won't allow it. You can be pretty sure that arrows on the cable jacket will be ignore much of the time.

 

[boneh3ad]

Yes, there are lots of examples of that sort of design. Loop-backs, interlocks, different shield terminations and such. But those are asymmetrical circuits not directional current flow through copper. In good designs you can't plug those in backwards, the connectors won't allow it. You can be pretty sure that arrows on the cable jacket will be ignore much of the time.

Unless the consumer is an audiophile, in which case you could probably convince them to add arrows to a cheap cable so that they plug it in the same way every time to help it become directional over time.

 

[Nik_2213]

"You don't get a diode simply by oxidizing a metal."
Um, before silicon, before germanium, before selenium, there were 'cats whisker' diodes. More relevant here, there were copper / copper oxide rectifiers.
https://en.wikipedia.org/wiki/Metal_rectifier

 

[Torbert]

Lamp cords run their wires parallel, twisted pair speaker wires cross each other at 90 degrees. I am sure an analyzer much more sensitive than my ear could detect a difference in an isolation room due to energy of varying frequencies trying to cause physical motion in the wires. Listening to Rock while driving down the freeway at 70 mph...I doubt the difference is detectable even with sensitive equipment.
Personally, for my analog signals, I use the fancy copper wire plated with fancy silver and given three layers of shielding.
The quality of sound coming from my fairly expensive home theater is matched only by the factory stereo system in a late model car.
It does seem as if spurious noise comes from the electronics themselves rather than the connectors.

I spent the last ten years before retirement at an electronics installation facility, mostly security but also video and stereo. Capacitance of the connectors becomes a factor when mixing brands, degrading the sound. Matching the cable to the unit is more important than 'directional' cables.

 

[DaveE]

twisted pair speaker wires cross each other at 90 degrees. I am sure an analyzer much more sensitive than my ear could detect a difference in an isolation room due to energy of varying frequencies trying to cause physical motion in the wires.

That's not why you twist wires. It's about cancelling induced voltage (or current) from external magnetic fields, or other signal pairs in the same cable (which seldom applies to speakers wires). Unless you have a very high impedance circuit (like some microphones) the noise induced by motion (like triboelectric effects) is negligible. Speakers are always a low impedance circuit in this regard. Plus physical motion of the wires would require gigantic fields.

Capacitance of the connectors becomes a factor when mixing brands..

At audio frequencies? Let's say you have 8 ohm speakers and you only care about frequencies below 50KHz, then any capacitance below about 400nF can be ignored in terms of amplitude, 40nF if you care about the phase shift. It's pretty damned hard to make a 40nF capacitor by accident.

Perfect examples of expertise in pseudo-science. Real EEs do use "an analyzer much more sensitive than my ear". Those instruments, plus book learning about the fundamentals of EE will allow you to quickly discount much of this BS.

Edit:

It does seem as if spurious noise comes from the electronics themselves rather than the connectors.

Yes, you are correct about this. Plus the source material.

 

[cjl]

While we are at it, I should also mention that audiophiles in general have effectively zero grasp on signals processing, specifically the Nyquist frequency and its implications. All of this high-resolution audio BS pilfered by people like Neil Young is pure snake oil.

It's worth noting that as with many audiophile beliefs, there's perhaps a grain of truth to this one. CDs only sample at 44.1kHz, and DVDs at 48, and in practice, it's at least non-trivial to make a brickwall filter that is down to effectively zero at 22kHz but has no phase or magnitude impact on 18-20kHz. There's a real argument to be made that sampling at perhaps 60kHz would make it far less likely for devices to have audible filter artifacts because then you'd have the entire range from 20-30kHz to implement your low pass filter.

Similarly, 16 bit is only 96dB of dynamic range, which means that you have to be a bit more careful with your mastering because if you have a mean level of say -30dB or so, it's possible you could start to hear some of the noise from dithering or quantization (if you have one of the awful "audiophile" DACs that doesn't dither) during quiet sections. This also applies to using digital volume control (say, the windows volume control on your computer) - if you're outputing a digital signal at 16 bits, and you turn the digital volume down 20-30dB, you could start to hear dithering noise during quiet periods (since you have to have more analog gain in your amp to compensate for the low digital volume level). 24 bit solves both of these issues - you could have a 24 bit encoded signal at a mean level of -50dB and the dithering/quantization noise will still be completely inaudible.

Of course, that's not the argument they're using, and with a properly implemented filter (which is definitely possible), 44.1 is definitely sufficient for audibly perfect results.

 

[cjl]

Customer on Phone with Service Rep: "Hey, I just spent $1000 on these new speaker cables and they don't sound any better than the lamp cord I have been using..."
Service Rep: "Hmm, are you sure you have them oriented correctly?"
Customer: "What?"
Service Rep: "They have to be oriented correctly: The arrow must be pointing towards the speaker."
Customer: "Wait, let me try that. ... Wow, you're right! I can hear a difference. The sound is more articulate and involving..."

The point is, people want to hear an improvement. The audio companies just give them what they want. If you think the $1000 cables sound better, wait until you audition your buddy's system, he bought the $2000 cables (the gallium arsenide-free version).

I tend to believe that this also is part of the reason why they go on and on about break-in. If it takes a thousand hours before the cables "relax" and sound their best, you've likely completely forgotten what your old ones sound like, and are likely also past the return period.

 

[anorlunda]

Being hard of hearing offers little cause to rejoice. But this may be an exception. In the case of audio equipment, my hearing cutoff at 2 kHz appears to be a blessing. I can buy satisfactory audio equipment at the dollar store.

 

[vanhees71]

I guess that's in the same category as claiming that a gold cable is much better than copper cable, and then there may be a specially gifted guru, who can make that even better only by touching it once with his magical hands. Of course this makes the cable by an order of magnitude more expensive than a normal one, let alone the pure material and frabrication costs, but only such an expensive cable has the promised effect, and this may even be true, because the placebo effect works the better to more expensive a product is.

Another great example is the filter for electricity from nuclear power plants. Just buy this precious device, and you'll be save from getting the very dangerous electric current produced by nuclear power plants.

Also of ustmost importance for you health is to prevent your bottled water from being scanned by the cashier since the interaction of the very dangerous light with the bar code produces very bad vibrations in the water. But it's easy, just buy a special pen with a magical ink to erase the bar code...

 

[Ibix]

then there may be a specially gifted guru,

I imagine that there is a team of such gurus, and they are the ones who determine which way the arrow should point. The company can then point to this team and say that "in their expert opinion" there's a directionality to the cable, and if you can't see the emperor's new clothes hear it then the problem is in your ears. I suspect that covers them legally, up to a proper double-blind test of the experts' opinions...