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Author Topic: OT: Is an old mic cable as good as a new one?  (Read 4959 times)

Mark Lemaire

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OT: Is an old mic cable as good as a new one?
« on: February 09, 2012, 04:48:53 PM »

..I am not speaking of design here, but of wear: is there anything in a cable that 'wears out' or decays? I understand that contacts need to be cleaned, but am wondering if some of my cables (that are as much as 40 years old) are as good as they ever were? I don't hear a problem, but am simply wondering what consensus there might be he at the forum.
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klaus

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Re: OT: Is an old mic cable as good as a new one?
« Reply #1 on: February 09, 2012, 05:14:41 PM »

First response (eventual consensus or not):

I have in daily use cables of high quality that were made more than fifty years ago. When I compare them to cables with the same construction but of recent manufacture, I cannot detect either structural or audible differences.
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Klaus Heyne
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J.J. Blair

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Re: OT: Is an old mic cable as good as a new one?
« Reply #2 on: February 09, 2012, 06:58:38 PM »

What I understand is that as long as the copper is low in oxygen content, and does not oxidize, there should be no perceivable difference.  Certain crappy Chinese brands oxidize, and cause extra capacitance, essentially turning your cable into a filter. 

One problem I have experienced is with a very old U47 cable, where the rubber shielding broke down, and the 105V got passed into the ground when I grabbed the mic, which was a very painful experience!  I replaced it with Gotham, which Klaus and others recommended.  (My only issue with Gotham is that their shielding has memory, and makes it a pain in the butt to coil it cleanly.)

Anyway, that rubber issue was with the old Neumann black cable.  I've never had an issue with their grey cables.  It's definitely a different type of rubber with does dry or crack, or disintegrate. 
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Mark Lemaire

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Re: OT: Is an old mic cable as good as a new one?
« Reply #3 on: February 09, 2012, 07:30:27 PM »

Good point, JJ, about oxidization (sp?). The term 'low oxygen copper' has come into my radar only recently (last 15 years?). 40 or 50 year old cable may predate the term, but perhaps is 'low oxygen' anyway and still works well?

Klaus- glad to hear your experiece is similar to mine.
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John Roberts {JR}

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Re: OT: Is an old mic cable as good as a new one?
« Reply #4 on: February 09, 2012, 11:23:04 PM »

Come on??? Low oxygen copper? The difference in wire resistance for very high purity copper is only 1% and oxygen free has nothing to do with oxidation, it's about the purity of the copper the wire is made from.

If you can hear a 1% difference in your wire resistance, drop down to a fatter wire gauge and enjoy a lot more than 1% improvement.

Old cables are OK of they are well built and not abused. Instrument cables and cables used in live sound with constant set up and tear down get a lot more wear and tear, than cables that get plugged up and forgotten, so old cables used hard may experience more opens/or shorts. I don't know if rubber is still commonly used for insulation, in the way back machine they used cloth.   

40 or 50 years ago may predate star-quad and the sundry copy cats, but basic wire hasn't changed that much, IMO.

JR
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J.J. Blair

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Re: OT: Is an old mic cable as good as a new one?
« Reply #5 on: February 10, 2012, 05:28:45 PM »

John, many years ago, before I knew things, I had bought a Hosa snake.  I had noticed a low end deficiency.  It had been explained to me that it was the oxidation that caused the capacitance, which was turning the cable into a high pass filter.  Are you saying that it something else that causes the capacitance?  I'd love to know what it is. 

My wiring person, who was not trying to sell me anything, said they found the cheap chinese cables were having this problem, and it was due to the problem I stated.  If I've been misinformed this whole time, I'd love to know the truth.

This 47 cables definitely had rubber insulation around each individual wire. I don't recall if there were string.  I probably still have the cable.  I'll see if I can dig it up and take a picture. 
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GYMusic

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Re: OT: Is an old mic cable as good as a new one?
« Reply #6 on: February 10, 2012, 07:47:33 PM »

I have many 25' mic cables that I made up in the early 70's with Belden 8413 and Switchcraft connectors that still work great.

John Roberts {JR}

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Re: OT: Is an old mic cable as good as a new one?
« Reply #7 on: February 10, 2012, 08:26:10 PM »

John, many years ago, before I knew things, I had bought a Hosa snake.  I had noticed a low end deficiency.  It had been explained to me that it was the oxidation that caused the capacitance, which was turning the cable into a high pass filter.  Are you saying that it something else that causes the capacitance?  I'd love to know what it is. 
Assuming you are serious I will try to answer.

Capacitance is an electrical property generally between two flat spaced plates where the amount of capacitance is directly proportional to the area of the capacitors plates and inversely proportional to the distance between them. Capacitance in a cable is dominated by the physical spacing between conductors and geometry... A shielded cable will have more effective surface area than simple twisted pair.

Oxidation is a chemical reaction (like steel rusting, or wood burning). Copper wire "rusting" is not going to make a noticeable difference in cable capacitance per foot. Nor is it likely to "rust" away from the ends. Any oxygen present as an impurity in the copper wire isn't likely to do much more than react with nearby copper atoms.

Where you could experience audible degradation from oxidation is in the connectors. Most oxides are insulators (some are semi-conductors), but none are capacitors, sorry. So oxidized pins in a cable connector can disrupt signal integrity and is a common problem.     
Quote
My wiring person, who was not trying to sell me anything, said they found the cheap chinese cables were having this problem, and it was due to the problem I stated.  If I've been misinformed this whole time, I'd love to know the truth.
Cheap cables often use cheap connectors made of substandard contact materials. I've even experienced bad connectors from good connector companies, stuff happens.

Another related problem is switch contacts on insert jacks that can get dirty and/or oxidized and causing intermittent signal flow. One reason gold is so desirable for switch contacts and connector pins is because it doesn't "rust" (oxidize).
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This 47 cables definitely had rubber insulation around each individual wire. I don't recall if there were string.  I probably still have the cable.  I'll see if I can dig it up and take a picture.

Plain rubber can break down over time (like old auto tires). In fact I think the rubber oxidizes too, but it still doesn't turn into a capacitor. Modern wire insulation is probably superior to simple rubber. 

So yes oxidation can be bad because it increases contact resistance, not capacitance.

I hope this helps.

JR
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J.J. Blair

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Re: OT: Is an old mic cable as good as a new one?
« Reply #8 on: February 16, 2012, 12:53:24 PM »

Thanks for correcting the misunderstanding.  I know that all cables have some dielectrical properties, but I seem to have misunderstood as to whether or not that value can change, or why.

BTW, I wasn't suggesting that the rubber caused capacitance.  I was saying the breakdown let to shorting with the other wires. 
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Ward Pike

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Re: OT: Is an old mic cable as good as a new one?
« Reply #9 on: April 24, 2012, 02:42:06 PM »

Every one of the 40+ cable in my arsenal was made by me in 1991 using Canare Star Quad and a combination of Switchcraft/Neutrik XLR plugs.

They're all still working perfectly.  Sound absolutely mint.
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