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A mechanism that could explain cable burn in. I’m not saying this is wrong or right I’m just saying that from what I have read on the subject and from what I know about plastics I believe this to be a plausible theory. I’m not sure I can give GFuNK the physics behind it but I’m willing to give it a shot. I’m thinking about ICs with this but the same would apply to speaker cables. I have read somewhere (can’t remember where but I agree with it) that you don’t burn in metal, you burn in plastic. How can that happen you ask, well grab a drink and make yourself comfortable, this could take a fair amount of typing on my part. An IC is a number of strands of copper (sometimes silver) wrapped in plastic and attached to connectors. They all have connectors, so I’m not interested in them, they all have a different number of copper strands of different thicknesses, I am interested in that but not until later for now I want to focus on the copper and the plastic. Plastic, we are told, is a dielectric material and as such it can hold a charge for just a bit longer than we would like it to (referred to as its capacitance) and thus can affect the signal being sent along it. For burn in to be real that capacitance would have to change, yes? And it can, but to explain how I have to back peddle a little. Plastic as we know it is not just a homogenous substance, or, to put it another way, just as oils aint oils, plastics aint plastics. When plastic is manufactured it starts out in a large vat that contains potential plastic (called monomers) and an organic solvent. When those monomers polymerize to form a solid plastic they join together in a very haphazard fashion and some of the solvent is trapped within the plastic. Over time this solvent will slowly evaporate leaving only the plastic. That new car smell that people often talk about, that smell is the solvent evaporating from the plastic in the dash (and steering wheel, gear stick, etc) as the sun “burns in†your new cars dash the amount of solvent you can smell decreases with time until there is no more new car smell (OK, your car won’t sound different, but it is a fair analogy). I believe this is what is happening to the plastic insulation of the IC as it is in use, the current flowing through the copper is changing the properties of the plastic in contact with the wire by evaporating some of the solvent present and so the effective capacitance of the plastic changes over time until there is so little of the solvent left that the properties of the plastic stabilize and the IC is considered burnt in. Now, I said above that plastics aint plastics, this is very true. There are three main plastics that manufacturers use to insulate ICs, Teflon, Polyethylene and PVC and all have different “capacitanceâ€. Within polyethylene there are low, medium and high density polyethylene and each are manufactured in a slightly different way. They can also be applied in more than one way. I have copied the following from Redgums website. I am not trying to pick on Redgum in any way, they are just one of the few companies that actually supply a decent amount of info in regards to their IC construction. REDGUM’s RGAP 'Audio Pipeline' OFC Interconnect The Design: The REDGUM RGAP 'Audio Pipeline' OFC interconnect cables are researched, developed, designed and manufactured in conjunction with some of the most knowledgeable specialists in the industry. Designed to provide focus and sound staging, with a strong sense of three-dimensionality, resolution and detail, take a listen and prepare to be amazed! The Construction: The Centre (signal) conductor comprises of a bundle of 80 cores of 0.09mm Oxygen Free Copper conductor (OFC), lightly twisted, and encased in a special foamed polyethylene insulating jacket. Both channels are then individually screened to a low noise specification with a 12-section x 9-strand spc braided OFC sheath, designed to achieve excellent RF rejection, very low capacitance and a low noise floor. The final outer covering is a matte blue jacket with silver printing. The cable is terminated with gold-plated RCA connectors, which feature an easy grip, ergonomically designed barrel, a Teflon insulator, and matching matte blue jackets. The Result: The REDGUM RGAP 'Audio Pipeline' OFC interconnect accurately extracts the maximum available information from a recording without ever erring towards artifice or over-emphasis. The Low capacitance results in less high frequency attenuation and distortion. What you get is a cable capable of clarity and signal integrity even over very long distances. Reproduction spans a broad and unencumbered frequency range with smooth, effortless and seamless integration from very low to very high frequencies, without introducing any unnatural peaks or troughs. The Technicals: These are real-world measurements of a totally finished cable, including the gold RCA plug terminations: Length Resistance Inductance Capacitance RGAP1 1m 0.08 ohms 0.18uH @200kHz 82.3pF @200kHz RGAP05 0.5m 0.04 ohms 0.09uH @200kHz 55.7pF @200kHz The short Technical version: Is it a good cable? - Yes, it is! So we have “foamed†polyethylene (don’t know what density, but the foamed bit is interesting, it seems that Redgum have a different way of applying the dielectric to the copper wire or maybe everyone else does it too and Redgum are the only ones who tell us this, who really knows) applied to 80 cores of 0.09mm copper wire. OK, just had a thought while I was typing, if this pet theory of mine is a goer then it should take longer to burn in an IC that has more surface area of copper in contact with the dielectric, so an 80 strand IC should take longer to burn in than a 40 strand IC (assuming the same weight of copper), I wonder if anyone has ever tried. Sorry, derailed my own train of thought there. What all of this means, very broadly speaking, is that ICs are going to need different amounts of burn in depending on the number strands of metal, the plastic in use and the method of application of the plastic. Then there are the cable companies that apply custom dielectric coatings, JW audio and anti cables are two which spring to mind. They apply a thin film of some proprietary substance and claim that it has a very low capacitance. Fair enough, let’s think about this for a minute. If the dielectric is very thin then there is far less in the way of solvent that could be trapped within it, there is also less of it present to “store†charge so the capacitance of the dielectric should be minimized and any change due to burn in should also be minimized. With this in mind the protection that the dielectric offers to the copper cable is probably also minimized so this may not be the best way to go. If I can quote from another web site, Mike Lenehan has this to say about his Ribbontec IC. If anything, we are even more excited about the results from our new Ribbontek interconnect. A specific width of copper foil receives the same initial preparation as the speaker wire, but is then treated with a coating to prevent oxidation, allowing us to use an air primary dielectric. By avoiding both the undesirable interactions of stranded cable and the skin effect problems of solid core wire, the Ribbontek interconnect offers smoothness, resolution and rhythmic drive that surpasses anything we’ve heard. An “air primary dielectric†sounds like a good way to minimize any copper/plastic capacitance as well as any burn in effects. And he uses copper foil, I have a few ideas about that too but I’ll keep those for another time, another post. So, assuming anyone is still with me after wading through all that, my theory is that the effect of burn in on ICs is due to the changing of the capacitance due to the evaporation of solvent from the dielectric material of the IC sheath. Is anyone still awake out there?

I must confess to being sceptical about this issue and provocatively suggest it is the user being burned in. Let me explain. I have no argument with the proposition that every component has its own signature, yes often subtle and not easy to detect, but it is there. No two amplifiers sound exactly the same. Yes, they might measure the same on test equipment but the human brain is a far far more sensitive instrument and can detect differences in sound that are currently unmeasurable. And my argument is this is the reason for the so called burn in affect. What is in play here is that any new item introduced into the audio chain does subtly change the sound. As time progresses the brain becomes more accustomed to the changed sound so a placebo effect kicks in and the item is pronounced as “sounding even better” . But is it really any better? I guess there is no definite way of deciding if the above is right or wrong because the perception of audio quality in the above scenario is completely subjective and unmeasurable. I would love to be directed to scientific (not subjective) research which has verified a measured change in say a cable after it has “burned in”. Audio memory is notoriously unreliable so I am skeptical at the claims a cable or whatever sound *better* after a period of burn in. But of course this really does not matter. If someone has increasing enjoyment over time in listening to music with the new toy, that is all that is important. Conversely, if the new toy does not sound as good as the item it replaced, then the audiophile has been genuinely burned themselves!!