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In Reply to: RE: Cable shootout... Are all audio cables the same? posted by geoffkait on June 21, 2014 at 20:54:03
So, you pass DC through the cable instead of audio?
Fwiw, there are a few signals that are somewhat asymmetric but audio signals alternate direction with a sum that has no DC offset.
Perhaps i am not understanding what you mean, describe what you mean as it would appear on an oscilloscope screen, microphone voltage or other metric
AC refers to alternating current, not alternating signal. There is no alternating voltage either. Thus, when measured a wire or cable will register slightly lower resistance in one direction than the other and more importantly will sound better in one direction than the other.
If you do a faurier analysis of an audio signal you find the signal is the combination of a bunch of sine waves which are alternating in polarity. Audio signals produce alternating current in cables
Sine waves are not alternating current. Nor do audio signals produce alternating current. Hel-loo! The audio signal is the thing that's moving at near light speed down the track.
Dude Hel-loo, ALL as in 100% of analog audio signals are alternating voltages and if there is a load a the end of the cable opposite the source (which there always is), the current that flows also alternates and both V and I propagate the signal near the speed of light (cable propagation velocity).
Uh, dude,the whole point is the SIGNAL is not changing directions, the upstream and downstream directions. That is why wire directionality is audible. That is why interconnects and speaker cables are frequently labeled with ARROWS pointing from the source to the amp. Hel-loo! All that other stuff, the electrons, the voltage and the current, you can throw out.
Dude, you are hopelessly confused with marketing spray.
I will try to explain in non-engineering terms for you.
In 100% of all analogue audio signals, “the signal” IS conveyed by the voltage.
Starting with the microphone, the alternating pressure which IS SOUND is converted to an alternating voltage where there is a precise relationship between the voltage and the pressure (positive and negative) that the microphone experiences. In fact, one can determine the sound pressure IF one has the Voltage at any given instant AND the microphone sensitivity, a Sound level meter simply converts that voltage (rectified) into a meter reading.
Ending with the loudspeaker the Voltage = pressure relationship is preserved and the perfect loudspeaker produces a pressure exactly proportional to the Voltage, independent of frequency , the inverse of the microphone.
In all cases, the signal is an alternating signal that ends up producing sound pressure that is positive and negative relative to ambient air pressure.
So far I have not heard you say that the audio signal itself, the electromagnetic wave, the one that travels down the cable at near light speed, is alternating back and forth along the cable (as claimed by naysayers of wire directionality). You've been dancing all around it, So, whaddya think, is the audio signal traveling down the cable in one direction only?
“So far I have not heard you say that the audio signal itself, the electromagnetic wave, the one that travels down the cable at near light speed, is alternating back and forth along the cable (as claimed by naysayers of wire directionality)”
Well that is true, I have not said that.
Perhaps I can clarify this further but it will involve some electronic engineering.
It is current alone that produces the H or magnetic induction resulting in a magnetic field B, it is Voltage across a load or resistance which causes current to flow.
The signal Voltage propagates at the cables propagation velocity and is set by the cables series inductance and parallel capacitance and can vary from near light speed to as slow as near half light speed.
It sounds like your confusion is based on the “signal” being somehow different than the Voltage which is the signal.
If interested, the next edition of “Handbook for Sound Engineers” being printed now has a chapter on loudspeakers which goes into this exact thing in some detail.
“So, whaddya think, is the audio signal traveling down the cable in one direction only?”
Again some confusion, YOU are the one who thinks “the signal” travels one way better than the other, my point is “the signal” is a Voltage magnitude referenced AC signal which spends half the time going one way and half the other.
The only things that propagate at light speed are photons and an electromagnetic wave such as light (photons) or RF, X-rays, etc. The reason electromagnetic waves travel at the speed of light is because the wave is composed of photons which, you will recall, have a constant speed in the universe - the speed of light, 186,000 miles per second. Maybe voltage is also composed of photons, you tell me.
The only thing that propagates at the speed of light is electromagnetic radiation in a vacuum, light (also electromagnetic radiation) traveling through glass, water or other materials travels slower and as a result we can have lenses which bend light.
Electromagnetic radiation propagates in two components, a Voltage field and 90 degrees apart, a Magnetic field and that is much like sound which propagates with two components, the familiar “sound pressure” and 90 degrees apart the less well known particle velocity.
With light however the wavelength as one departs the microwave range into far far infra red, the wavelength becomes too short to discern the two parts separately. None the less, light and radio are a continuum.
It remains that the “signal” we call analogue audio, is an alternating voltage referenced signal which propagates at the cables velocity factor. This may help, from an area where this is critical and well studied;
Exactly what I have been saying all along. Hel-loo!! The velocity is of the electromagnetic wave. You still have not shown that the electromagnetic wave is alternating directions, however. So I remain unconvinced. Besides EVEN IF the EW IS CHANGING DIRECTIONS, which I actually doubt, the only direction that counts is the direction pointing toward the speakers from the amp. So, directionality of wire can still be real and still be audible since one direction would be more "favorable" to the signal traveling toward the speakers. Or, in the case of ICs, more favorable to the signal traveling from source to amp.
What electromagnetic wave are you talking about, cables at audio frequencies are FAR FAR too short to have any transmission line or wave behavior and there is no standing wave in audio cables.
To be clear too, the audio signal isn’t an electromagnetic wave, it’s a Voltage referenced signal, it is so starting at a microphone and ending with a loudspeaker and there isn’t anything about cables that make them “signal directional” with an AC signal.
If you don’t believe it’s ac, get an oscilloscope, set it to a DC or ground reference and look at any analogue signal you choose, or if you do digital, get a wave editor like cool edit and zoom in on the wave form, what do you see? Ans, a signal that goes positive and negative, just like the air pressure than we hear as sound.
Now I don’t doubt you can hear a difference, but it isn’t related to the signal passing through it and if this effect were actually present, it would be part of RF engineering where everything becomes more of an issue. Hell-ooo the effect is because you know which way the arrow points and when it’s “right’.
We're a long way from a meeting of the minds. The article you linked to states the audio signal is an electromagnetic wave and most references also state that the audio signal is an electromagnetic wave. It makes no sense to say its a voltage or that the voltage has velocity as you claim. As I have already stated on more fhan two occasions the signal much be electromagnetic because only photons can travel at light speed or near light speed in a medium. I never said the cable is not AC, the only question is what does AC really mean. As I said in my previous post, EVEN IF THE ELECTROMAGNETIC WAVE ALTERNATES BACK AND FORTH ALONG THE CABLE AS YOU CLAIMED AT ONE POINT IT IS THE DIRECTION TOWARD THE SPEAKERS THAT COUNTS. So wire directionality would be important even if the audio signal is alternating. Hel-loo!
As far as wire directionality goes it is obvious when listening even when there ARE NO ARROWS to influence you. Are you that easily influenced? This is true for speaker cables, interconnects and fuses. Hel-loo! I suspect this might be another case where someone has fabricated a theory of convenience to explain a strongly held belief that wire directionality is false and ALL EVIDENCE to the contrary further buttresses that belief.
Going further, what this whole issue of wire directionality really means is that ALL internal wires and cables, crossovers, transformers, capacitors, etc. should be fabricated with the correct direction established and indicated with arrows and that all speakers, electronics, and cables should be manufactured with wire directionality in mind. Anything less is just hiding one's head in the sand.
Wow, a "gold star" for persistence, the consummate audio salesman type, unfortunately untainted by engineering and also possibly hallucinating.
For example for hallucinating, what article are you talking about that “I linked” talking about directionality and a number of your assertions such as; “Sine waves are not alternating current. Nor do audio signals produce alternating current. Hel-loo! The audio signal is the thing that's moving at near light speed down the track. “???.
The thing I linked here was about cable velocity which is 100% engineering related and says NOTHING about audio or directionality unless you can read what wasn’t printed or intended.
At the same time you avoid addressing any of the things I brought up and say silly things like;
“Nor do audio signals produce alternating current. Hel-loo!
Hel-loo Geof, your right we ARE a LONG way from a meeting of the minds, you’re talking the language of alchemy and audio trinket sales, I’m talking the language of chemistry and electronic engineering and design no wonder there is no common ground and your unable or unwilling to answer even my simplest engineering question with a direct answer like;
“Ok, i am game, in exactly what way are they directional and how large is that effect an alternating signal like audio?”
Sure we can hear things, but we also "hear" things unrelated to what arrives at our ears and influenced by what we know and believe.
If this signal directionality and “audio is not an ac signal ”is a real effect, it exists in the electronic domain, not just in one’s head, show me some evidence of that.
Sure I am skeptical, audio has been a lifetime love, I have worked in both electronic and RF engineering most all my life, much of that time designing circuitry that works, even flown on the space shuttle (sts-7 and sts-51a).
This makes it rather hard to believe here is something about audio traveling down cables that isn’t present at all at frequencies above 20Khz or below 20Hz..
You said “I suspect this might be another case where someone has fabricated a theory of convenience to explain a strongly held belief that wire directionality is false and ALL EVIDENCE to the contrary further buttresses that belief.”
Show me engineering evidence, any evidence at all, some mechanism, or measurements this exists in audio for directionality, where it doesn’t for RF, more arm waving and smug salesman talk won't do it..
I was quite sure this "discussion" would deteriorate into name calling and silliness. Thanks for making my prophecy come true. Some people refuse to come out of their caves.
Similarly, from the start, i pretty much assumed you couldn't answer in an engineering fashion or answer even one question honestly, but is was fun to see how far you would bend before bailing out.
Fwiw, Engineering isn't silliness, its what honest design depends on but it's never to late to learn something new, hence a number of sincere attempts to get you to explain directionality leading to the conclusion you can't and are an alchemist in a world of chemistry.
More jibber jabber from the man who lives in a cave. An engineer, a real engineer, would have gotten to the bottom of this whole wire directionality thing a long time ago. You rely on phoney arguments like "voltage velocity" and other pseudo engineering terminology. It's apparently true what they say, you can't teach an old dog new tricks.
Why Geoff I am glad to not be your kind of engineer in fact I am an inventor and here are a couple samples of what I have done “living in a cave” as you put it;
The first invention link might even appeal to you especially as it looks like magic to most and all are the result of understanding how things work;
Would “your kind” of engineer have inventions which changed the way things are done, some examples;
Or would “your kind” of engineer have changed the face of large scale sound in just a few years?
Have you ever been to a stadium and heard what concert speakers sound like?, they don’t sound like this.
Pop on some headphones; By this fall, 4 years after introducing the products, we will have provided the sound systems for more than half of the 100,000 seat stadiums in the USA.
Soon there will be several recording studios using our smaller Synergy horn loudspeaker systems for monitoring audio too and next season we are introducing a new “stereo capture” system which can capture an entire hemisphere, try a recording or two, again use headphones.
So, this is sort of fun, teach me a new trick Geoff, somehow in some way if at all possible, try to describe how / why audio signals aren’t AC and audio cables and wire are signal directional.
Have you ever looked at the output of a phono cartridge, CD player, pre-amp or power amplifier with an oscilloscope?
What does one see?
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