The speaker cone isn't cracked. That's a baseless assertion - I agree with
@RobL's post just above.
The company provided high-res photos of multiple drivers fresh off the production line in this thread:
I started a bit of a rant on this other thread and eventually got blocked by the mods, so I'm posting a new thread just to clear the air, because Genelec were kind enough to email me close-up pics of the race track woofers to prove they all look like that and it's perfectly normal. They also...
www.audiosciencereview.com
Here's one of the photos:
View attachment 309174
The cone is glass-reinforced paper. The stated purpose of this kind of composite material is to balance flexibility with rigidity; hence two materials, one (glass) more rigid than the other (paper).
From the photo, several characteristics are obvious:
- The two materials are not mixed together at the chemical or molecular level. The individual fibers are clearly visible, and the glass fibers are easily distinguishable in color (and perhaps reflectivity of light) from the wood/paper fibers. So the cone material does not have uniform flexibility or rigidity at the microscopic level.
- This construction gives the material a textured surface, and a relatively rough surface when seen close-up like here. This is clearly visible in the main concave "basket" part of the cone, not just the edges.
- Judging by the lower-right corner of this photo, the fibers appear to be arranged in a circular or elliptical pattern (which makes sense given the circular interior and the oval shape of the driver).
With these facts in mind, it seems clear that what we are seeing on the straight edge of the cone just inside the surround is a textured, composite fiber material with a curved "grain" pattern, pulled and secured over a linear ridge with a tight radius to it.
When you pull any material with a textured surface over a convex radius, the "valleys" in the texture spread out, and the "peaks" become farther apart. Here's a quick photo I just took of a plush carpet remnant:
View attachment 309179
At the bottom of the photo, the carpet pile is evenly textured with no notable gaps. On the upper left side of the photo, the carpet is curving over a relatively gentle radius, and there are a couple of very small gaps but the pile is still basically even-looking. Towards the right, as you get closer to where my hand is forcing the carpet into a tighter radius, the pile opens up and the large gaps at the apex of the radius are easily visible.
This is what's happening on the surface of the Genelec cone. Where the elliptical pattern of the fibers intersect that tight-radius edge at something close to a perpendicular angle, the fibers are bending over the radius - we don't see broken ends of fibers sticking up (like if you broke a piece of celery in half). Where the elliptical fiber pattern intersects that straight edge at more of a parallel angle, the surface fibers are spreading out like with the carpet.
Now, if the fiber pattern were exactly the same throughout the entire thickness of the cone material - if every fiber we see on the surface had other fibers lined up directly underneath it in the exact same direction/angle - then yes, the entire cone fabric would pull apart at those places where the fibers are basically parallel with the straight edge of the racetrack driver. shape. But obviously that's not the case - the many, many layers of fibers are not perfectly lined up with each other, which is what gives the material structural integrity.
With all that said, when the cones move over and over, minute vibrations will eventually create small tears at the weakest points. But since the areas in question are glued in place, are they really the weakest point? Or might the weakest point be where the unglued portion of the cone meets the glued portion? Or because that unglued portion closest to the glued portion will be vibrating less, might the weakest point be somewhere partway between the unglued edge of the cone and the center of the cone - somewhere where neither vibration force nor restriction of movement is maximal, but the two forces combine in a maximal way?
And wherever the weakest part of the cone might be, which will eventually tear, how long would it take, and under what conditions, for it to tear? Five years of average use? 50 years of constant use? More or less time than the MTBF (mean time between failures) of some other component or material in the speakers?
The answer is, we don't know.
But one thing I think we can say with confidence is that the claim that the cones are "cracked," "tearing," or otherwise compromised in their design or manufacture, is a claim that has no evidence to support it, and a claim that does not hold up to scrutiny given the information currently available to us.
The one somewhat refreshing silver lining of this thread is that at least a couple of participants have been quite up-front (wittingly or not) about the degree to which anxiety, obsession, and aesthetics are driving their concerns here. So unless someone gets ahold of the exact materials spec for that cone fabric and does some complex computer modeling that proves the areas in question are likely to fail, or unless someone finds reports of distorted bass, failed woofers at that point in the cone, these concerns have long ago crossed the line into FUD.
