Axiom Home Page Forums General Discussion Home Theater New M22 speakers.... break-in required?

And I expected better from you. You quoted and baited me, and you know you did. Stop pretending to be the innocent victim. If you honestly did not intend to do so, I will be more than willing to offer you a sincere apology and buy you a beer.
But if my initial take on your words was accurate, you were being a prick. If you were, it’s not a big deal to me. I have my moments just like anyone else and expect to be called out when I do.



I’ll make one last attempt to explain this in a manner that should be understandable to anyone who would like to understand and learn and discuss, and not just argue or disagree, just for the sake of being disagreeable. It should also shed some light on why I choose the analogy I did I which has become the target of ridicule – a tire tube, for my thoughts regarding driver break in possibilities.

Drivers use some form of elastic material as part of their physical make up. I do not know the exact molecular composition (don't really care either), however, whatever it is; it is a polymer based product. (I’m talking specifically to the part of driver that surrounds the cone) Casual observance leads me to believe they are an elastomer (rubber) of sorts, probably with a proprietary blend of sulfur. (Sulfur is added to rubber to increase hardness IE: Vucanization). Inner tubes are also made from rubber, again, why I used the tire tube analogy.

The molecular structure of polymers, in general, and if observed through a microscope, resembles cooked spaghetti; the molecules rap around each other, coil and intertwine in a haphazard sort of way. The molecules are attracted to each other through Van der Waals forces (non-typical, molecular week bonds of attraction), which holds them together. This is what gives polymers elastic properties - their molecular composition. As they are stretched, the molecules straighten out and align in the direction they are stretched while Van der Waals forces keep them from sliding apart and becoming unattractive to one another and moving away from each other. When tension is removed, the molecules attempt to resume their original shape and orientation - provided that other factors like heat, absence of heat, rubbing, cracking, over stressing, etc does not occur. If excessive stress is applied, the Van der Waals forces that hold the molecules together give out and the (straightened) molecules slide by one another and cracks form, which allows the polymer (rubber) to fail (rupture, break, etc). Google “fracture mechanics” if interested in this…..

Now, regarding driver break in and my initial thoughts regarding drivers which should tie this to my analogy of a rubber inner tube….

Polymers, specifically rubber, have viscoelastic properties (time dependent strain). This, in a nutshell, means that if stress is applied (stretch) over a given period of time, the molecular structure is changed from a pile of sticky intertwined spaghetti, to non sticky rows of straightened spaghetti, making the rubber stronger and more resistant to failure from cracking after the stress is relieved, because the molecules reorientate to their original state with more rigor and defined structure. There are two different approaches to strengthening rubber through its inherent viscoelastic properties: 1) creep, 2) stress relaxation. Both have the same desired affect, which is reorienting the rubber’s molecular structure to make it stronger and more resistant to cracking (failure). Creep is when a constant tension is applied to the rubber and stress relaxation is when constant stress is applied to the rubber, but the rubber is held in constant position and not allowed to continue stretching. If you were to take the inner tube and pull it from end to end two inches, and hold that position over time; that would be stress relaxation. If you were to pull on the inner tube with a steady, constant pressure, you would continue to stretch it, elongating it, further and further. That would be creep. For both techniques, after stressing the inner tube for a given period of time, you then remove the stress that was applied and allow it to return to its original size / shape. The molecules are now reoriented. You do this same thing by inflating the inner tube, allowing time for the viscoelastic properties to take effect, and then deflate it.

The same principles could be related to a speaker driver, although more loosely. If one were to “flex” the rubber component over a particular amount of time by some form of mild use (low wattage break in perhaps), the likelihood of rubber cracking would be reduced, reducing the chance of failure. This is somewhat of a stretch (no pun intended), but possible, I believe.

Vulcanizing is another factor to consider that affects rubber, which in short, is when “spot welding” of the molecular polymer chains occurs by cross linking the sulfur atoms that were added to the original compound during the manufacturing process. Unwanted or uncontrolled "spot" vulcanizing limits elastic properties and creates failure points. Mild spot vulcanizing occurs when rubber is tightly folded upon itself (inner tube wrinkles caused by packaging) or if excessive heat is applied, or if left in sunlight or in an overly dry or humid environment. Some of the affects of vulcanizing can be reversed by reorienting the molecular structure through stress relaxing or creep. (inflating the inner tube and then deflating it)

In the industrial world, it is common practice to stress polymer based components before installing them or putting them in service (Example: diaphragms for control valves and actuators, accumulator bladders). It is a proven, and well known practice.

Am I overworking this when relating it to speakers?? More than likely. I was curious, always have been.