It would have been in first year electromagnetics, where circuit theory is shown to be the low frequency approximation of EM. Then you just have to know that an audio wire forms a trivial part of a potential divider, so any reasonable conductor (e.g. any metal, or a banana) surrounded by any reasonable insulator (typically, mostly air) will be sufficient.
Triboelectric effect is proposed as a plausible culprit in the conversation about Teflon insulated silver wire. Online there is conversation of triboelectric effect causing noise in cables; guitar cables as an example.
The claim regarding silver wire causing a bright harsh sound relates only to silver plated wire. I did not find any reference to similarly harsh sounding silver only wire.
Scratching my head about the bright harsh sound of silver plated copper wire, if it in fact happens, thermoelectric effect comes to mind. There may possibly be a bimetal effect as well. It could be all about the heat.
The silver plated copper conductor has a copper inner core and a silver outer layer. Silver has about 6% greater conductivity than copper. As AC flows in the composite conductor more current will pass through the silver than the copper. I see the potential for local voltage differences, heating rates, thermal expansion and stress all related to current and AC frequency.
Remember the primary mechanism for resistor distortion is heat and to lesser extent voltage.
Anyone with an Audio Precision APx555 that wants to test this? Just an idea.
DT
The claim regarding silver wire causing a bright harsh sound relates only to silver plated wire. I did not find any reference to similarly harsh sounding silver only wire.
Scratching my head about the bright harsh sound of silver plated copper wire, if it in fact happens, thermoelectric effect comes to mind. There may possibly be a bimetal effect as well. It could be all about the heat.
The silver plated copper conductor has a copper inner core and a silver outer layer. Silver has about 6% greater conductivity than copper. As AC flows in the composite conductor more current will pass through the silver than the copper. I see the potential for local voltage differences, heating rates, thermal expansion and stress all related to current and AC frequency.
Remember the primary mechanism for resistor distortion is heat and to lesser extent voltage.
Anyone with an Audio Precision APx555 that wants to test this? Just an idea.
DT
I don't think you will get much heating. Copper and silver are good heat conductors so the heat will be distributed fairly evenly. Thermoelectric effects, if significant, would be at bass or signal envelope frequencies, not mid-range or treble. I don't see a problem. There is no hard evidence that there is a problem.
There are many other dielectrics you could use instead of PTFE, with excellent properties, and in many cases, very limp. Also you could look at foamed dielectrics (eg foamed PE) which incorporate air ( = 1 ) to result in dielectrics near or sometimes exceeding PTFE.
As I understand it, silver coated copper PTFE wire is used in aviation and aerospace to minimize corrosion and to tolerate extreme temperature conditions. Sometimes there are fires, explosions, etc in these vehicles and you want to minimize the impact ... a half-working sat is still worth millions per year to the owner, or a damaged aircraft benefits from minimal associated damage to get safely to the ground.
Not to be overlooked, these vehicles also must be able to tolerate very cold conditions as well; PTFE does well in that environment, or one where the temperature varies from very cold to hot in relatively short periods of time.
Some dielectrics cannot be used in passenger carrying vehicles (passenger also = crew only) due to toxic gases in fault conditions. PTFE is not an angel in this regard but apparently it's not bad enough; if you survive the fire you will survive the PTFE emissions. Rumours about space crews perishing in fires due to poisoning seem to be unfounded; the fire apparently did the damage itself.
Although I don't know if it's an issue, rocket fuel is generally highly corrosive stuff, as are some fuels used in aviation. Maybe small emissions during launch or operation could get into the payload or structure, thus the desire for corrosion resistance.
I hadn't considered the manufacturing process, but that does make sense.
PTFE also has the negative quality of migration; it doesn't stay in the manufactured shape forever, and can expose the bare conductor at pinch points, etc over time. So careful dressing / routing of the wire is recommended. (Many years ago the crew I hung with would machine Teflon "buttons" to serve as piston keepers in high performance internal combustion engines. They had to be replaced regularly as they would change shape over time).
Silver-coated PTFE wire is readily available as remnants because aviation / aerospace / NASA requirements are no more than one splice in a run of wire, so not all of a spool can be used in production.
As always, there are advantages and dis-advantages to any dielectric material.
As I understand it, silver coated copper PTFE wire is used in aviation and aerospace to minimize corrosion and to tolerate extreme temperature conditions. Sometimes there are fires, explosions, etc in these vehicles and you want to minimize the impact ... a half-working sat is still worth millions per year to the owner, or a damaged aircraft benefits from minimal associated damage to get safely to the ground.
Not to be overlooked, these vehicles also must be able to tolerate very cold conditions as well; PTFE does well in that environment, or one where the temperature varies from very cold to hot in relatively short periods of time.
Some dielectrics cannot be used in passenger carrying vehicles (passenger also = crew only) due to toxic gases in fault conditions. PTFE is not an angel in this regard but apparently it's not bad enough; if you survive the fire you will survive the PTFE emissions. Rumours about space crews perishing in fires due to poisoning seem to be unfounded; the fire apparently did the damage itself.
Although I don't know if it's an issue, rocket fuel is generally highly corrosive stuff, as are some fuels used in aviation. Maybe small emissions during launch or operation could get into the payload or structure, thus the desire for corrosion resistance.
I hadn't considered the manufacturing process, but that does make sense.
PTFE also has the negative quality of migration; it doesn't stay in the manufactured shape forever, and can expose the bare conductor at pinch points, etc over time. So careful dressing / routing of the wire is recommended. (Many years ago the crew I hung with would machine Teflon "buttons" to serve as piston keepers in high performance internal combustion engines. They had to be replaced regularly as they would change shape over time).
Silver-coated PTFE wire is readily available as remnants because aviation / aerospace / NASA requirements are no more than one splice in a run of wire, so not all of a spool can be used in production.
As always, there are advantages and dis-advantages to any dielectric material.
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I have also heard (but not experienced) that PTFE can migrate with twisted-pair assemblies; ie not manufactured wire which is machine-twisted but in hand-twisted pairs.
While Silver has about 6% greater conductivity than copper, this only applies if the two wires have exactly the same cross-section area. Does a 100 inch long copper wire sound different than a 106 inch long copper wire? I don't think so.
It's unlikely that the end-to-end resistance/impedance of any chassis wire matters.
It's unlikely that the end-to-end resistance/impedance of any chassis wire matters.
There are people that report a harsh mid frequency sound from silver plated copper Teflon insulated wire.
Another possible mechanism is frequency dependent “velocity of propagation”. Take a look at a couple of cable specifications. You will find that the “velocity of propagation” commonly will vary between 0.6 and 0.8 times the speed of light in a vacuum depending on the type of conductor and insulator.
I learned a couple of; new to me, things about silver plated copper Teflon insulated wire. Often the copper core is alloyed with other metals for greater tensile strength. Think about how much force can be applied when pulling a bundle of wire through a conduit. The silver plating that is applied to the copper core is much smoother than copper alone can be. The smooth silver surface has reduced resistance as the frequency increases.
See the Belden link a few posts back.
Testing may show frequency dependent group delay for silver plated copper Teflon insulated wire.
Speed of electricity flow (speed of current.)
DT
Another possible mechanism is frequency dependent “velocity of propagation”. Take a look at a couple of cable specifications. You will find that the “velocity of propagation” commonly will vary between 0.6 and 0.8 times the speed of light in a vacuum depending on the type of conductor and insulator.
I learned a couple of; new to me, things about silver plated copper Teflon insulated wire. Often the copper core is alloyed with other metals for greater tensile strength. Think about how much force can be applied when pulling a bundle of wire through a conduit. The silver plating that is applied to the copper core is much smoother than copper alone can be. The smooth silver surface has reduced resistance as the frequency increases.
See the Belden link a few posts back.
Testing may show frequency dependent group delay for silver plated copper Teflon insulated wire.
Speed of electricity flow (speed of current.)
DT
Which means significative boost, at least a few dB at midrange frequencies, or at frequencies a couple octaves higher so they emphasize distortion or cable nonlinearity which actually *generates* an important level of distortion and annoying harmonics.
Any and all these variations on signal passing through suspect wire are easily measurable ... if existent that is ......
A parallel experiment would be a double blind one comparing perceived or stated harshness.
Very unlikely, given how short domestic audio cables are.DualTriode said:
No. That is for RF use of the cables, where the speed depends on the insulator - not the conductor. For audio the speed depends on the conductor, and it is much slower - yet still fast enough not to be an issue unless you are laying long-distance telephone cables.
I think this effect comes into play at microwave frequencies and above?
You are grasping at straws to 'explain' a phenomenon which almost certainly does not even exist.
Hello,
Seems that if there were harsh things going on in the midrange it would show up in a FFT.
I got out the basic QA401 analyzer, 3 resistors from the used junk bag and about 100 feet of 24AWG silver plated Teflon insulated wire. The resistors were all Vishay- Dale RN60…’s 1/2 watt metal film types; 300R, 267R and 10R. The silver plated 24AWG wire measures about 8R over the 100foot length.
I soldered the 300R and 10R in series and I soldered the 267R and the 8R wire in series.
Everything was put on the floor and tested in turn with the QA401. The big ball of wire acted as an antenna and picked up from the computer power supply. The signal output was placed over each of the series assemblies. The analyzer input was placed in turn over the 10R and then over the 8R wire. Technique borrowed from D Self’s small signal book.
Next try everything was tested inside an isolated steel junction box. Things cleaned up nicely.
There was nothing really notably different between the resistors in series and the similar value resistor is series with the 8R wire. There is nothing to see here.
DT
Seems that if there were harsh things going on in the midrange it would show up in a FFT.
I got out the basic QA401 analyzer, 3 resistors from the used junk bag and about 100 feet of 24AWG silver plated Teflon insulated wire. The resistors were all Vishay- Dale RN60…’s 1/2 watt metal film types; 300R, 267R and 10R. The silver plated 24AWG wire measures about 8R over the 100foot length.
I soldered the 300R and 10R in series and I soldered the 267R and the 8R wire in series.
Everything was put on the floor and tested in turn with the QA401. The big ball of wire acted as an antenna and picked up from the computer power supply. The signal output was placed over each of the series assemblies. The analyzer input was placed in turn over the 10R and then over the 8R wire. Technique borrowed from D Self’s small signal book.
Next try everything was tested inside an isolated steel junction box. Things cleaned up nicely.
There was nothing really notably different between the resistors in series and the similar value resistor is series with the 8R wire. There is nothing to see here.
DT
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All that is needed to get audio from here to there (a few metres away) is a reasonably good conductor surrounded by a reasonably good insulator. Metals are many orders of magnitude better conductors than we need for this task; air is many orders of magnitude better as an insulator than we need. Hence it is completely unsurprising that simple audio cables work (whatever metal or insulator they use), and only very cheap, very expensive and DIY cables fail to do this simple job
Some silver wire to experiment with. And only $9000.
Everyday Objects ball of yarn in sterling silver. | Tiffany & Co.
Everyday Objects ball of yarn in sterling silver. | Tiffany & Co.
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