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Technical Article: Does Audio Cable Skin Effect Matter

SIY

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Why is PVC "a problematic insulator"?
Clear PVC. The pigmented stuff doesn't usually cause the same corrosion issues.

Home Depot is about 160 km away for me as well, but I used that as a generic term for "big box home improvement/hardware centers." My last speaker cable purchase was outdoor wiring from Ace Hardware about 5km away from me.
 

Urubamba

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Clear vinyl is a problematic insulator. It's probably OK, but just for peace of mind, get thee to Home Depot and get some 12x2 zip cord with opaque insulation.
These are NOT OFC cables, obviously. The wire that has oxidized is 40 years old, and it connects my tube amplifier to the main speakers. (2.5 meters each )
The "new" looking cable is three years old and links my SS amplifier to the subwoofers. ( 3 meters each and spliced and welded because I cut "in half" before measuring ) yes, the years do not come alone .... :facepalm:
I change the old cables for new ones? The new one also because it has been spliced?
Will the rust be superficial or will it be present on all internal stranded conductors?
I would like to know what you would do if you were in my place.
Thank you ! ;)
This question remains unanswered, does anyone know what happens in there? Will each braided section be attacked by surface rust?
I really wouldn't want to have to cut through one of them to find out.....
 

SIY

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This question remains unanswered, does anyone know what happens in there? Will each braided section be attacked by surface rust?
I really wouldn't want to have to cut through one of them to find out.....
Depends on time and how tightly the strands are wrapped. Eventually yes, but how long to migrate past the surface is only determinable by experiment.
 

Urubamba

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I worked for the company that made the "oxidized" cables in the previous photo here in my country. The first (I think) "special speaker cables" in the USA, the Monster Cable, were taken as an example. We upgraded them with red and black caps and gold-plated studs on their ends, back in the days of push-on/bare-wire connectors, used on both amps and speakers.
I still have the ends I cut off so I can use "U" terminals, so I'll take a look at them and let you know.
I bet the inner conductors aren't oxidized because, as you say, if the wires are too tight, oxygen/moisture won't get in.
But I wonder why so many cable manufacturers keep using transparent PVC if its chemical composition helps oxidation, probably because the appearance is attractive, seeing the inside of the cable is like seeing the "soul" of the sound for many audiophiles. You see that I don't care, I also listen to music closing my eyes when I want to concentrate....:rolleyes:
 

fpitas

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My woofer runs are clear PVC 10AWG. The oxidizing copper gives me that dirty bass :rolleyes:;)
 

wwenze

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I worked for the company that made the "oxidized" cables in the previous photo here in my country. The first (I think) "special speaker cables" in the USA, the Monster Cable, were taken as an example. We upgraded them with red and black caps and gold-plated studs on their ends, back in the days of push-on/bare-wire connectors, used on both amps and speakers.
I still have the ends I cut off so I can use "U" terminals, so I'll take a look at them and let you know.
I bet the inner conductors aren't oxidized because, as you say, if the wires are too tight, oxygen/moisture won't get in.
But I wonder why so many cable manufacturers keep using transparent PVC if its chemical composition helps oxidation, probably because the appearance is attractive, seeing the inside of the cable is like seeing the "soul" of the sound for many audiophiles. You see that I don't care, I also listen to music closing my eyes when I want to concentrate....:rolleyes:

Don't forget to tin one of the side so one side is copper and the other side is silver-colored for extra sound quality. Even Audioengine does that. Tho this is useful when trying to figure out the polarity.
 

Urubamba

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o_O You do not understand. I do not believe or buy snake oil. I worked in that company, it wasn't my idea to make them, but I had to sweat a lot to sell them. (my area was commercial)
So I'll let you guys have your fun with your jokes. (unless you believe in what you recommend)

Don't forget to tin one of the side so one side is copper and the other side is silver-colored for extra sound quality. Even Audioengine does that. Tho this is useful when trying to figure out the polarity.
 

Plcamp

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I remember skin effect mattered quite a bit in 1980’s in our design of high current switching power supplies running at about 25 kHz. We needed either foil or multi #18 wire or Litz secondary (high current) windings on the transformers in order to minimize and balance core and copper losses in the finished magnetic.

Now, that application has dramatically more high freq content than audio has, and I would be surprised if there are significant current levels above 10 kHz in audio we listen to?
 

fpitas

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I remember skin effect mattered quite a bit in 1980’s in our design of high current switching power supplies running at about 25 kHz. We needed either foil or multi #18 wire or Litz secondary (high current) windings on the transformers in order to minimize and balance core and copper losses in the finished magnetic.

Now, that application has dramatically more high freq content than audio has, and I would be surprised if there are significant current levels above 10 kHz in audio we listen to?
If there are, your ear drums have turned to dust.
 

fpitas

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I remember skin effect mattered quite a bit in 1980’s in our design of high current switching power supplies running at about 25 kHz. We needed either foil or multi #18 wire or Litz secondary (high current) windings on the transformers in order to minimize and balance core and copper losses in the finished magnetic.

Now, that application has dramatically more high freq content than audio has, and I would be surprised if there are significant current levels above 10 kHz in audio we listen to?
Unless you were working with resonant converters, the waveforms were probably squarish. Meaning frequencies to 250kHz and beyond.
 

Urubamba

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The mystery cleared up, the rust is only superficial, which would seem to confirm Siy's theory, the culprit would be the PVC when it is in direct contact with the copper... although let me confirm this, I'll wait another 40 years to see what happened with the new cables I bought... :eek:

SIY: We had a Cocker Spaniel's dog in my family too....sniff.... ;)
 

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Audiofire

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the culprit would be the PVC when it is in direct contact with the copper
PVC is white, so that would be the "best" color for speaker cables if there is such a thing. But it's not normal PVC cable that makes copper so black. It it additives or something like water that causes so much oxidation or discoloration on your copper.

Black cables are best if they are cheapest or in case of direct, strong sunlight on cables like outdoors. This is because the black carbon material is more sunlight resistant.
 
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SIY

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The mystery cleared up, the rust is only superficial, which would seem to confirm Siy's theory, the culprit would be the PVC when it is in direct contact with the copper... although let me confirm this, I'll wait another 40 years to see what happened with the new cables I bought... :eek:

SIY: We had a Cocker Spaniel's dog in my family too....sniff.... ;)
Sunny is cute! Here's my new puppy (13 weeks old).

1678662417681.png
 

Urubamba

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Thank you ! She was very fine, as she befits a lady.
And your new dog looks "naughty", what "brand" is it?
 

Urubamba

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PVC is white, so that would be the "best" color for speaker cables if there is such a thing. But it's not normal PVC cable that makes copper so black. It it additives or something like water that causes so much oxidation or discoloration on your copper.

Black cables are best if they are cheapest or in case of direct, strong sunlight on cables like outdoors. This is because the black carbon material is more sunlight resistant.
Whatever it is, if it doesn't affect the music, why worry, right? In those years there was already talk that the unions of the speaker cables should not be soldered (and if someone committed that "heresy" use silver) but "stapled", we put a washer and gave it a "hammer" blow as you can see in the photos. But when presenting them - in our small market -, we had to do the advertising in the most popular local magazine, and due to lack of time it was done with a cable without the "special" connectors as you can see in the photos.
Observe the detail of the groove in the tip so that the pressure connector falls there and does not slide.....
 

Audiofire

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Whatever it is, if it doesn't affect the music, why worry, right? In those years there was already talk that the unions of the speaker cables should not be soldered (and if someone committed that "heresy" use silver) but "stapled", we put a washer and gave it a "hammer" blow as you can see in the photos. But when presenting them - in our small market -, we had to do the advertising in the most popular local magazine, and due to lack of time it was done with a cable without the "special" connectors as you can see in the photos.
Observe the detail of the groove in the tip so that the pressure connector falls there and does not slide.....
Resistance is easy to measure and this shows if the music is affected by comparing resistivity of copper. Besides that really bad oxidation might make stranded copper more like the litz wire, and would reduce skin effect. A good thing according to the audio mystics out there who do not care about factual investigation.
 
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Urubamba

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Resistance is easy to measure and this shows if the music is affected by comparing resistivity of copper. Besides that really bad oxidation might make stranded copper more like the litz wire, and would reduce skin effect. A good thing according to the audio mystics out there who do not care about factual investigation.
Superficial oxide will not alter the skin effect or the resistance in such a few meters of this 12 AWG/2.05 mm section cable, such as to hear any difference in sound when compared to the cable without oxide. It does not worry me.
1000 feet = 304.8 linear meters = 1.62 Ohms.

 
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