[timoteus]

Underneath the open cell foam sheeting that keeps debris away from the driver you will find a circle of plastic and three struts directly over the driver.

Is this merely added protection to keep fingers from damaging the driver or is this some kind of phase device or other enhancement designed to tweak frequency response?

In speaker design it is desirable to eliminate the grill cloth covering the driver. This is what I have done with my speakers and HD600s. The more you remove between the driver and your ear the more revealing the sound and the details will be less muffled. Or so goes the theory, I guess this could be debatable in some instances.

If this plastic device is part of the driver design I would of course leave it alone. If it is merely for the protection of the driver I guess my next question would be...who wants to volunteer to take a shearcutter to the struts and remove the plastic covering the driver?

 

[JaZZ]

It's probably both. Someone has removed it and reported that the effect wasn't positive. Usually I too tend to remove all acoustic barricades and disturbing factors in front of tweeters, but in the case of headphone drivers you have not the same possibilities to compensate for the sonic consequences (via crossover network). The best you can do is replace the foam pads by some thin fabric (nylon gauze, pantyhose...). That's what I've done; you get more treble and less bass.

 

[Dusty Chalk]

Quote:

Originally posted by timoteus In speaker design it is desirable to eliminate the grill cloth covering the driver.

Not necessarily, it depends on how the speaker or headphone was designed. Headphones are usually designed "as is", so I would say leave it alone. I know of at least one pair of speakers that were designed with the grill cloth in place (van somethings), and a review I read even reflected the speakers' superiority with the grill cloth in place.

 

[timoteus]

Are you thinking of Vandersteen Audio possibly?

I tried to write my statement as a general rule.
Quote:

In speaker design it is desirable to eliminate the grill cloth covering the driver. This is what I have done with my speakers and HD600s. The more you remove between the driver and your ear the more revealing the sound and the details will be less muffled. Or so goes the theory, I guess this could be debatable in some instances.

I think your example is an exception to that rule. Even when you have to use grill cloth because of children, pets, dust etc. you would typically want to choose the most acoustically transparent cloth you could find. An exception to this rule would be cloth for a guitar amp.

Anyways, after reading the post by JaZZ I don't think I will be mutilating my HD600s any time soon. If this removal mod has been tried already with lackluster results then I would have to make the leap that the Senn engineers were using this device to alter high frequency response and not just to protect the drivers.

As a sidenote, Jan Meier has said that Sennheiser keeps abreast of the activity here at Head-Fi. If this is true then I hope that they will feel free to jump in any time. An update on the progress with the HD700 would be helpful also.