Speak for yourself!
3 Likes
Well yes maybe a misuse of words. That strengthens the need for references I suppose. 
If the scientist specialises in electrons etc. and know little about metallurgy, the answer could very well be yes.
Impurity effects on the grain boundary cohesion in copper
As the report title indicates (linked below) it discusses the effects impurities have on the grain boundary cohesion in copper.
So, grain boundary cohesion is a thing, as is grain boundary decohesion. The report discusses the effect it has on mechanical properties. Would anybody bet their house on grain boundary decohesion not effecting electrical properties. I doubt it.
1 Like
Is it measurable? If so, is it audible?
The rest is a distraction
Good summary.
What if it isn’t measurable but it is audible to you ?
This study appears to focus on the brittleness of polycrystalline alloys, copper mixed with other electronegative materials. Most speaker cable is (almost) pure copper, or sometimes a copper core with aluminium cladding, but not the types of alloys in the study.
Conclusion from the study:
Our analysis shows that Mg, Al, and Si do not embrittle Cu, P can improve the ductility
of polycrystalline copper, and S can cause intergranular embrittlement of Cu.
So as long as we don’t contaminate our speaker cables with Sulfur too much, it seems we are okay.
Copper alloys:
1 Like
Fron the report.
Segregated S at GBs is strongly detrimental and several ppm of residual S can remarkably embrittle copper.
10 parts per million is 0.0001%. That level is an impurity, not an alloying element. 
Your link indicates copper used in electrical equipment is 99.9% pure, so 0.1% impurities.
I did state. The report discusses the effect it has on mechanical properties.
The point I was making is there a phenomenon called grain boundary cohesion and as the report states (in the title of the report) this is affected by impurities.
Now, as a signal travels along a length of copper wire, it is jumping from grain to grain. All I’m suggesting is, if impurities cause reduced cohesion between grains, this could hinder the signal jumping from grain to grain. (Along with the layer of impurities that surround the grain)
1 Like
And the line below that reads:
However, the addition of about 50 wt ppm of the neighboring element P can cure the Cu embrittlement problem and recover the ductility of polycrystalline copper
It’s just a very narrow scenario. Magnesium, Aluminium and Silicon residue have no significant effect. Sulfur residue can make copper alloys more brittle but Phosporus makes it more ductile. There is no mention of any effect on conductive properties.
For our current topic of cable burn-in, i don’t think there is much we can conclude from this…
At the grain boundary (GB) , not in the material as a whole, they are two different percentages that cannot be compared like that.
The numbers posted earlier were: Standard copper wire is around 99.95% pure, 0.03% O2, and less than 50 ppm metallic impurities.
So in order to make it more brittle, most of those 50 ppm have to be Sulfur exclusively and they have to be concentrated at the GBs without any presence of Phosphorous. I have no idea how likely or unlikely that is.
At this time in the process, we need to discover the empirical evidence.
…then it’s time for explanations.
(Rather than the other way around)
There is absolutely no way i could disagree with anything you propose.
I just dont know why i cant get this kind of argument elsewhere!
OK I can see some acknowledgement of the problems and efforts to alleviate them.
I also remember listening tests via spk - will leave this and other areas of concern as
the detail is insufficient. You clearly are trying to maintain an even handed approach
but i fear measurement will not suffice. I can not Quite shake a earlier belief that jumped out at me in the beginning that you are simply a naive magnet for the gullible section of
the Burn in deniers.
It is not your sentiment i fault. It is the ability to satisfactory carry out of the Practical and
then the Audible tests. It is a fact your group states it has no ability to hear anything
if it can not be measured. You are in a Huddle of like minded souls devising your means
to your thoughts only. The Subjectives are just told what will happen.
This is not Scientific as i see it.
.
Not sure what that claim is?? You have your approach and i notice it has been ineffectual.
I will take apart argument as i see fit and i will not give up that right especially when i am
Winning and i will continue to Win as they are Wrong. Over the length of this Forum the
Anti Burn in Boat has been shot full of so many holes it leaks like a sieve,
and it is only now they feel the water lapping at their ankles.
Time for a quite burial and a playing of the last post!
Well I am glad you think you are winning. Don’t let me stop you!
3 Likes
I’m begining to chuckle now! What was previously just plain rude is now becoming amusing…what is next I wonder?
4 Likes
I very much think that this will NOT be the last post on this thread (or even the subject for that matter)!
Not possible. The human ear / brain is nowhere near as sensitive as equipment. If the ear can sense it, then a machine should easily be able to detect it.
2 Likes
I don’t know what causes you to assign me to a ‘group’ of such people. I have never said that, so please don’t ascribe such things to me… in fact I have said, though not sure whether or not in this thread, that I can accept that ears may be more sensitive to certain aspects of sound or sound differences than measuring devices, or at least some measuring devices, and that there is also a question as to what to measure. And I have read contributions by other people in this thread apparently keen on the idea of testing who have said similar things.
What I read of scientists and engineers in this thread is that at least some cannot conceive of any reason why a cable might change as a result of use, yet there are well known physiological and psychological reasons why someone may believe the sound has changed over time in use. I think most of those people welcome the notion of testing - both blind comparative listening tests, and if a it is definitive that a difference is audible then as many electrical and physical tests as possible to try to find what has changed. And from that might come explanation that those with inquisitive minds would like to understand. These people - in which ‘group’ I would accept you placing me - have open minds and want to learn, but don’t want to be persuaded simply by belief, nor fooled by their own minds.
6 Likes
I think the above statement does not give the human ear / brain enough credit.
At this point, in terms of neural networks and human perceptual capacity, we are still well ahead of machines so while machines may be better in measuring sound levels, they don’t come close to being able to measure how your brain deciphers that information or, if it is missing out key data that our brains pickup on.
For instance, I have cameras with very sensitive image sensors cable of capturing extreme levels of detail… far more than the human eye is capable of seeing. Our brain however takes the same data as the camera (light) but turns it into an image in our minds that not only shows way more dynamic range but also has superb depth of field and positioning. An image captured by a machine (camera) mimics this but isn’t able to translate / present it into something that feels real.
What if, like the visual cues the brain uses to create a real looking world from light data, there are audible ones that are not being picked up or presented by machines?
Just thinking out aloud. As I say, I think you under estimate the capabilities you already have compared to a machine. I also don’t think we fully understand how and what we hear. I found a google of “Human hearing perception” very interesting.
3 Likes