I don't mean to turn this thread into a "component burn in",
but since the topic came up, I would like to at least talk
about the science behind the cause of "burn in".
We learn a lot through our visual process. We see things
as they happen and learn from them. If something we are
unable to see, then a lot of times we think that they don't
happen or we don't believe that they happen. A good example
would be current flowing inside a conductor. We can't see
current flowing so a lot of people have a hard time understanding
what's going on unless one has the electrical engineering
background and experiences.
First let's talk about something we see and agree.
There are a lot of processes that alter the nature of metal.
For example, metal annealing is a process which uses heat
to alter the metal crystal structure. Most people would
understand this because they can see the actual process
with their own eyes.
Another example of metal burn in is to literally burn it.
If you apply a high enough current to a conductor, it will
burn which is a permanent and irreversible process. Most
people can easily understand this since he can see it with
his own eye. "Copper got burnt" is a layman term, but
the scientific term is called metal oxidization.
The high current creates heat which enables the copper
and oxygen molecules to interact to become copper oxide.
Copper oxide turns to black color therefore we can see
it with our own eyes so we believe the metal got "burnt".
Now if copper oxide has no color, then it would be harder
for people to believe it.
Now you don't have to run a current through copper to
turn copper into copper oxide. You can literally burn
it with a fire. So the root cause of copper oxide is
heat and it could come from anything that has heat.
Heat is also a layman term, but in science heat comes
from the speed of the molecule or any particle. If
a molecule has a high velocity, it has a high amount of
heat (or energy). So the fundamental of heat is particle
velocity scientifically.
But you also see copper turns into copper oxide without
any high current or "heat", but the reality is statistically,
at room temperature, there are always some copper molecules
that have higher high velocity (or hotter) than the average
molecules, so those molecules with higher than average speed
will interact with oxygen to become copper oxide. Most
people without a scientific background probably don't
see this and probably cannot visualize this whole process.
The key here is the word "statically".
It's similar to water vapor. Most of the water sitting
inside your house will not vapor. But there are also
some water molecules that will have higher speed than
the average water molecules so they can jump into the air.
All I said above to show that molecules are not that
different from a billiard ball since they move, they
get bounced around, push around just like regular
objects.
Electrons for the most parts behave like billiard
ball in the same way they got move around. If
you use the equation to describe for example electron
mobility, the principals behind them basically
come from the equation: F = ma. In layman term,
electron mobility is how much it moves in (m/s)
when it gets push. But you say "aha, electrons
get pushed by electrical field, but things like
billiard ball gets pushed differently". But I say
"aha back at you, when you push something in the
real world, what actually going on at the molecular
level is that your molecule electric field pushes
at someone else electric field but you just don't
see it". Your molecules never actually touch someone
else molecules. It's only the field that interacts
even in the real world. You see when you see thing at the
molecule level, things don't look that much different.
Electron motilities are used to calculate resistance.
In metal, there are a lot more
free electron so electrons are "free er to move",
therefore they have higher mobility vs. insulator.
When electrons move, they bounce around within the
metal structure. The higher the current, the more
likely and stronger they bounce and hit other things within the
metal structure, in this case other molecules. When
it happens, electrons transfer its speed to the molecules
which in turn the molecules will have higher speed.
High enough current will eventually give higher speed
molecule and will heat up the copper conductor.
Let's turn to the science behind our layman term
"cable burn in". Most people would agree that at
high enough current, with enough heat, it can potentially
alter the metal structure permanently because we
can see them visually with our own eyes so believe
it.
But the problem is at low current, such as at our
audio system level, most people don't believe the
current is high enough to alter the crystal structure
of the metal. This is where it is harder to explain
unless you have a background in electrical engineer.
It took me years of going to school and experiences so
I guess I can understand most people are skeptical.
One has to understand the metal structure is not perfect
and ideal. A metal structure also has a lot of impurities
such as oxygen molecules. When electrons move, they
encounter a lot of obstacles (otherwise there wouldn't
be heat). And statistically, some electrons even at
low current, will acquire a lot of energy equivalent
to that of higher current, it then can impart enough
energy to a molecule to permanently dislodge a molecule
position permanently or the molecule can acquire enough energy
to be oxidized and turned into copper oxide. When the
copper becomes oxidized, its electrons will not be conductive
(or you can say its electrons now have much lower mobility).
That's why audiophile grade cables typically use higher
oxygen free conductor. These oxygen molecules can either
oxidize copper molecule or they can obstruct the path of
the electrons. If you measure resistance at DC, the cables
probably are very close, but when you play music, our
hearing is sensitive enough to pick up the difference.
I guess this is where hearing and measurement start
to diverge - very small measurement difference but results
in large listening difference.
What I said above is to present a case in which how a small
current can potentially alter a molecule crystal structure
which results in cable break-in. I can explain further
but my guess is if you're skeptical, then I don't think
what I said would change your mind.
