# I Is a Copper Conductor Directional?

#### 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.

Gold Member
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.

Last edited:

#### 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.

#### 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.

#### 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

Mentor
Gold Member
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

Gold Member
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...

#### vanhees71

Gold Member
Well, the legal aspect is interesting too. Is it fraud to exhaust the superstition of people to ones advantage? As I said, it's an interesting question, but off topic in a physics forum ;-).

#### sysprog

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.
Most of us will settle for Gold.

#### fresh_42

Mentor
2018 Award
Seems it is time to close this thread.

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving