[zhenya]

 
 
 
Not sure where to post this, but I'm thinking I might get better technical responses here than in the general headphone forum.
 
Anyhow, I'm refurbishing a pair of Sony CD3000 and, as is the case with most of the soft parts of these cans, the original foam covering the driver grilles was disintegrated and had turned to a sticky goo, as per the pictures below:
 

 
I cleaned them up so that they now look like this:

 
My question is whether this kind of covering plays a part in tuning the sound of a driver, or if it is merely intended as a dust filter?  On the page I snagged these pictures from, the author implies that it does play a part in tuning (in my limited understanding from the Google translation from Japanese) and he recommends using tissue as a replacement cover.  I wasn't so sure, so I put them back together with nothing, figuring I could add a filter behind the earpads easily if I found it necessary.
 
Any ideas?  Sure, I can just try it, but I'm not a big believer in the ability (especially my ability) to tune equipment by ear, so I'd like to know the technical reasons here.  That said, I do find the CD3k to be a bit bright especially relative to my D7k's. 
 
TIA.

 

[NA Blur]

My guess is that it does three things:
 
1.)  Filters the sound from the driver to give slightly better bass response ( this is seen especially with Grado headphones )
2.)  Protect the driver from debris like hair or large pieces of dust that can get in the way of the diaphragm
3.)  Dampen the resonant frequencies of the driver so the harmonic distortion remains low and is not heard

 

[zhenya]

Quote:

My guess is that it does three things:
 
1.)  Filters the sound from the driver to give slightly better bass response ( this is seen especially with Grado headphones )
2.)  Protect the driver from debris like hair or large pieces of dust that can get in the way of the diaphragm
3.)  Dampen the resonant frequencies of the driver so the harmonic distortion remains low and is not heard

Thanks.  The CD3000 also has a second layer covering that sits closer to the earpads, cloth rather than foam, fwiw.
 
I have some old MDRV6 pads that have a foam backing I can use as a substitute and see how things go from there.

 

[liamstrain]

Nice job cleaning them up. I'd have been afraid of getting foam bits inside the driver. 

 

[zhenya]

Quote:

Nice job cleaning them up. I'd have been afraid of getting foam bits inside the driver. 

Thanks.  I just used a very soft detailing brush and a very light flow of compressed air.  The darn stuff turned so sticky that it was impossible to keep it entirely off the drivers though.