Cable Burn-In Test

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TJHUB

Re: Cable Burn-In Test
« Reply #20 on: 24 Aug 2016, 07:01 pm »
I'm going to hate myself for posting this, but oh well...

Back in 2009, I had 5 different speaker cables I was trying.  All of them basically copper, and I don't think any of them were OCC.  All had similar geometry.  3 sounded similar, 1 sounded very bright, and 1 was a mistake from a test batch of cable that sounded so dull it was like I put tape over my ribbon tweeters.  Out of curiosity, I set up my measuring gear, and proceed to measure each cable.  I ran the measurements twice, only changing the 1 speaker cable.  The test took maybe 10 minutes max both times.  Even though the 2 cables on the extremes sounded VERY different, every measurement was nearly identical.  What I mean is when I had all 5 measurements displayed, I could only see 1 line.  This happened exactly the same for both tests.  So what was at play here?  How is that possible?

Since that test, I put much less weight on frequency response measurements.  They just don't tell you nearly as much as people think they do.  It's just a small part of the story.  Where is the measurement for clarity?

No offense to Dave, but I too think measurements done days apart cannot be trusted.  There are far too many variables at play.  That said, what he found might still be possible, but I'm not certain how audible the change would be. 

OzarkTom

Re: Cable Burn-In Test
« Reply #21 on: 24 Aug 2016, 07:21 pm »
Some companies will burn your cables in for a fee. On power cables, I run them on a heavy duty fan for a week or two.

DaveC113

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Re: Cable Burn-In Test
« Reply #22 on: 24 Aug 2016, 07:46 pm »
The Omnimic fr measurements at higher frequencies are very repeatable. The test results are way outside the range of the measurement system's noise and the environment didn't change and wouldn't have much of an effect because of the way the test was done anyways. That said, yes the test could have been better but the cables tested were for a customer and I didn't want to burn in one cable, do the test, then burn in the second cable. While that would be better I don't think the results would be any different. But, because this test shows promise it can be followed up with a better test in the future, or even have other folks do tests who own better measurement equipment than I do. This was a simple, rough test that shows obvious changes due to burn-in.

I also did comment that frequency response is one of the least audible factors in burn-in, but in this case the litz-wire burn-in is rather extreme and makes fr changes easy to measure. With most cables I don't think this test would show much difference, certainly not to the extent my litz-wire cables do.

And fwiw, I burn-in all of my cables, including power cables and the power cable's ground wire, before shipping them and I think this is very important. Making a customer suffer through many hours/days/weeks of burn-in makes no sense to me. On power cables the ground may be very audible depending on your system and most cable burners make no provision for burning-in the ground wire, I had to modify my burner to do this.

Bob2

Re: Cable Burn-In Test
« Reply #23 on: 24 Aug 2016, 08:13 pm »
I would like to know what is happening to the cable during "burn in"? What is the change in the properties of the cable that takes place during this process? Is there a change to the constituent makeup of the cable?

Lots of talk about this process. Cannot say I have experienced it... Won't say that it does not happen.
Just trying to understand the process that brings about this change.


 

*Scotty*

Re: Cable Burn-In Test
« Reply #24 on: 24 Aug 2016, 08:31 pm »
Applied voltage to an insulator displaces molecules and when a high enough voltage is applied the molecular cohesion in the insulator will break down and if conditions are right the voltage may go to ground or to a location of lower voltage potential.
 Why this physical change in a cables insulation appears to be audible still remains to be explained.
Scotty

DaveC113

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Re: Cable Burn-In Test
« Reply #25 on: 24 Aug 2016, 10:30 pm »
Burn-in occurs in the interface between the conductor and it's dielectric. The cable tested uses over 1000 runs of 44g UPOCC copper insulated with enamel, so it has a lot of interface surface area and hence a very pronounced and extreme burn-in compared to cables made with conventional wire.

In this case we can see that the changes in the dielectric due to burn-in absorb energy, and likely some is re-released later, which might account for the poor subjective sound quality before burn-in and also why cables are always better after burn-in. The effect of the dielectric during burn-in seems to always be harmful to the signal.

Peter J

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Re: Cable Burn-In Test
« Reply #26 on: 25 Aug 2016, 12:17 am »
Burn-in occurs in the interface between the conductor and it's dielectric. The cable tested uses over 1000 runs of 44g UPOCC copper insulated with enamel, so it has a lot of interface surface area and hence a very pronounced and extreme burn-in compared to cables made with conventional wire.

In this case we can see that the changes in the dielectric due to burn-in absorb energy, and likely some is re-released later, which might account for the poor subjective sound quality before burn-in and also why cables are always better after burn-in. The effect of the dielectric during burn-in seems to always be harmful to the signal.

I'm curious about the physics of this. Does the dielectric conductor/interface stabilize at some point? Is it constantly changing with varying rates as time goes by or current passing? What happens with disuse? I don't mean poke a hornet's nest, but am genuinely curious.

Speedskater

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Re: Cable Burn-In Test
« Reply #27 on: 25 Aug 2016, 12:33 am »
The typical voltage & current ratings of wires & cables is very conservative. Audio signals don't stress the conductors or dielectric at all.

Peter J

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Re: Cable Burn-In Test
« Reply #28 on: 25 Aug 2016, 12:35 am »
I see comments like this often, but the answer is very simple.  No cable designer would ever design a cable for what it sounds like in the first couple hundred hours.  I'm certain they take a lot of time to sort out the sonic signature, so it seems obvious any cable design would be settled on far after the cable is fully broken in.  So when a new cable is built and requires break-in, wouldn't or shouldn't it always get better with break-in?

I just spent a week waiting for some new power cables to settle in.  It was a rough ride.  Just this past Saturday, I was thinking about a selling strategy.  Today, I think they're damn near perfect.

I don't think I've ever seen a comment to that effect, but admit I avoiding the seemingly endless debates. If all cables are "designed" how would the effect of varying lengths, different connectors, environmental conditions, and especially different equipment factor into it that design? I know, I know, synergy and all that. But if a designer is considering the cable itself and it's specific attributes, wouldn't those variables carry similar weight? Why not describe the equipment used for arriving at the desired sonic signature. The whole thing seems so ambiguous to me I find it difficult to assign credibility to much of it, and hence my skepticism.

I really don't doubt there are differences. I think the stick in my craw has more to do with the hyperbole and sometimes nonsense used to market the gear. I'm afraid it makes the industry less credible to my eyes thus fueling my skepticism.

Or maybe I'm having a bad day...


*Scotty*

Re: Cable Burn-In Test
« Reply #29 on: 25 Aug 2016, 12:59 am »
I strongly suspect that if we go any further down this path we run the risk of going straight down the rabbit hole that leads to the land of supposition and wild speculation. It seems to me that no one really knows what exactly happens during the "cable break-in process".
 Except for empirical evidence gained from single blind listening tests of identical cables in virgin and broken in condition producing consistently repeatable results indicating that something is actually happening, we really don't have any hard physical evidence substantiating an observable change in a cable. RCL parameters seem to be unchanged before and after break-in has occurred when this has been tested.
 Almost all competent analogue audio cable design is done by empirical testing of cable dielectrics and geometries that look like they ought to sound good. You don't know for sure if a cable is going to sound good until you build it. White papers are barely equivalent to old Wards and Sears catalogues and are seldom if ever on based good scientific methodology or an understanding of physics.
Scotty

audioguy213

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Re: Cable Burn-In Test
« Reply #30 on: 25 Aug 2016, 01:14 am »
Dave's cables sound better than others.
I wouldn't call them "burnt",
I would call them "just right,"

whatever you are doing , keep it up.

OzarkTom

Re: Cable Burn-In Test
« Reply #31 on: 25 Aug 2016, 01:51 am »
Even though I do not own Dave's cables, they are one of the best I have ever heard in my system. I would be curious to hear a cryo'd pair. Have you tried that Dave?

DaveC113

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Re: Cable Burn-In Test
« Reply #32 on: 25 Aug 2016, 02:07 am »
Even though I do not own Dave's cables, they are one of the best I have ever heard in my system. I would be curious to hear a cryo'd pair. Have you tried that Dave?

I have, cryo doesn't seem to have an audible effect on my cables. With UPOCC conductors already being close to a perfect continuous crystal I suppose there is no need. Most of my connectors are cryo'd from the factory though.

Peter J, I plan on writing a post on how I determine neutral, as that's the goal for my cables. There is a process and it does seem to work. As far as burn-in, I use the cable cooker then many hours in the system before I judge a cable.

audioguy, thanks! :)

Scotty, it is all speculation, I've said as much as I know at this point. The dielectric and interface surface area seem to be the main factors, but what actually happens seems to still be a mystery.

Bob2

Re: Cable Burn-In Test
« Reply #33 on: 25 Aug 2016, 03:07 am »
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« Last Edit: 6 Nov 2016, 04:11 am by Bob2 »

DaveC113

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Re: Cable Burn-In Test
« Reply #34 on: 25 Aug 2016, 03:39 am »
Bob, yes the enamel insulates, basically the same kind of insulation used on magnet wire. The 17g cable has about 1060 strands of 44g wire braided around a flat core and covered with a cotton jacket, so there's a lot more surface area between the wire and dielectric than in a conventional cable. Litz wire is intended to reduce AC impedance and skin effect.

I don't think there is a change in LCR values, rather the dielectric absorbs some energy as it does whatever it does. (WAG ;))

Another observation I (and many others) have made is that simply moving a cable can shift the relationship between the conductor and dielectric enough to require it to burn-in again, but only to a slight degree... the cable might only take a couple hours to settle down after it's moved around. Shipping can require another 8-12 hours or burn-in before it performs as-intended again, probably because it's moved around a lot more.

I think, outside audio, the effect of wire burn in is negligible enough not much energy has been devoted to understanding the phenomenon, although a lot of work has been put into understanding how capacitors and resistors change over time. I'm not sure how much, if any, the long term drift in gross values of capacitance and resistance relate to wire burn-in we're discussing here though.

DaveC113

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Re: Cable Burn-In Test
« Reply #35 on: 25 Aug 2016, 03:46 am »
Also, on another site a member pointed out the impedance peak of the speaker at 5 kHz correlates to the FR curves posted as the curves come closer together at 5 kHz.

Speaker measurements:

http://www.stereophile.com/content/pioneer-s-1ex-loudspeaker-measurements#ZhDkkFEvuSZ5jTUz.97

*Scotty*

Re: Cable Burn-In Test
« Reply #36 on: 25 Aug 2016, 04:21 am »
Bob, I would call Dave's statement from post #25 a hypothesis
Quote
Burn-in occurs in the interface between the conductor and it's dielectric. The cable tested uses over 1000 runs of 44g UPOCC copper insulated with enamel, so it has a lot of interface surface area and hence a very pronounced and extreme burn-in compared to cables made with conventional wire.
   Testing this hypothesis and controlling for all of the variables involved may be well nigh impossible.
 I think you may have misapplied the the term "emperical proof".
"Empirical evidence is information acquired by observation or experimentation. This data is recorded and analyzed by scientists and is a central process as part of the scientific method." (1)
 There is a preponderance of empirical evidence sufficient to substantiate that something related to passing an electrical signal through an audio cable causes the sound of cable to change over time.
I would call his hypothesis a SWAG  :thumb:
Scotty
1
From LiveScience :http://www.livescience.com/21456-empirical-evidence-a-definition.html

*Scotty*

Re: Cable Burn-In Test
« Reply #37 on: 25 Aug 2016, 04:27 am »
Dave, have you ever hooked up a sensitive LCR meter to the cables and moved them about while watching for a change in L or C parameters.
I am wondering if the conductors are shifting relative to one another and affecting the cables characteristic impedance value.
Scotty

Bob2

Re: Cable Burn-In Test
« Reply #38 on: 25 Aug 2016, 10:13 am »
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« Last Edit: 6 Nov 2016, 04:10 am by Bob2 »