Yep, I know what I told you and agree that ringing of some structural parts of a heaphone is something that needs to be avoided.
Now, recommending sorbo to every single headphone user out there is just like giving the same medical prescription to any patient because you found it worked well on some of them.
Sticking sorbo pads inside an headphone can mess up the tuning if the void is used to acoustically load the driver (and it most often is...), it adds acoustic absorption that may not necesseraly help. When applied to the exterior of a housing, it can also negatively affect the response of an open back headphone because you're altering the shape of the baffle (hence the acoustic loading on the driver). It's got potentially near zero influence on the mechanical damping depending on the receiving structure dynamics.
Keeping with the medical analogy, there is a good reason why people go see doctors who will diagnose illness before prescribing a given medication and make sure there won't be harmful side effects to the given patient.
On the other hand, you're like a sorcerer's apprentice with all this. You do not seem to grasp how intrusive your recommendations are nor can you scientifically highlight why and where it needs to be applied, hence simply recommending to put slabs of if every where you possibly can as it "most typically helps".
This, edstrelow, is why your systematic posts on sorbo grt annoying after a while, especially when you start to make claims that headphone manufacturers are starting to catch up with you revolutionary thoughts.
Arnaud
Some of your points are ok but you are also misrepresenting some of what I have been doing.
Certainly there is a lot of flying by the seat of one's pants here but that reflects the the lack of of knowledge and understanding of the damping phenomenon. Even with some companies working on damping issues, I have yet to see anyone able or willing to explain this other than what I have done. When I first started on this I simply noticed that the sound of a Stax SR-007 changed in an odd way simply by touching the headband. I could find nothing in discussion on this forum that explained this. It simply should not have made any difference but it did. But skipping a lot of investigation by me and others and which can be seen in other threads:
http://www.head-fi.org/t/744839/damping-mechanical-energy-distortion-of-stax-and-other-phones-with-sorbothane-and-other-materials and
http://www.head-fi.org/t/671314/stax-sr007-resonance-problems
it came down to vibrational energy from the drivers. I am
not just talking about resonant ringing although that is something which may also be damped with substances like sorbothane. Simple Newtonian physics tells us that there is equal and opposite energy going into the earcups because the driver is attached to it. Newton also tells us that energy cannot be created or destroyed so that which gets into the cups has to dissipate somehow. Sorbothane claims their materials convert the energy to heat.
Last year I spent two days at the Canjam in Southern California demonstrating this work and of the hundred or so who came by, not even a handful said they could not hear a difference. I also spoke to about 5-6 people who claimed to be working on similar issues, sometimes indicating they were professionals in the field but sometimes not identifying who they were. I also remember one guy came by with his badge tucked under so it couldn't be read. But one who said he was a mechanical engineer said my explanation sounded right to him because sometimes the simplest is the best. Is anyone in the field following me, I don't know. Certainly Stax isn't and that's their problem. They make excellent phones but they are obsolete in this respect and that is disappointing. I acknowledged Sennheiser's' prior work as soon as you told me about it. I even put up a poster of their work at my table at Canjam. However anyone can do their own diy work with sorbothane or whatever you want to try.
I see this work as an extension of what we have been doing with loudspeakers. We generally make the cases heavy, fill them with sand, put sorbothane footers, fasten then to the floor or walls or use spikes. However most of this, other than using damping materials like sorbothane, can't be done with headphones.
However none of this would matter if sorbothane damping didn't produce sonic benefits, but it does, so far on every phone I have tried whether electrostatic or dynamic and other people have made similar claims. Does it work all the time? No, but I have documented some phones that have given me troublesome anomalies, but I have eventually managed to get what I considered considerable improvements on all that I have worked with. It is easy to experiment with and all unlike many other tweaks, easily reversed since sorb is easy to remove. Its also cheap. You can get a 3 by 3 inch sheet of self-stick 1/4 inch 70 duro (my current recommendation) shipped for $6.00.
Why wasn't this discovered before? I suggest that we didn't have the damping materials until recently. The Stax Lambda series, still on Stax' current product line was released before sorbothane was patented. And other companies are now working on other materials. I expect to see more widespread adoption of these techniques over the next few years.
And as far as this thread is concerned, dynamics are one of the big benefits of this treatment.