Over a loan from a friend yesterday afternoon, I was able to get my hand ona DT990 for a few hours. Finally, I could not help but take it into pieces for its astonishingly resembling sound quality of DT880, yet with more dynamic and bass. Some may think DT990 would beat you more on comfort, though the pleasing sound of DT880 remains irresistible. In the end, I carried out an interesting experiment.
Taking it apart to begin with:
Just like other high end Beyerdynamic products, ear pad designs of DT880 and DT990 are more or less the same. They may be removed manually along their fitting edges.
Then removing the plastic ring cover. Use some small, hard gadget to gently poke at the fitting edge. The seal ringshould then come loose. After that, gently knocked on the back of the outer ear cup. The driver plate should then come out by itself.
Now you can get to see the entire driver. The structure of rear magnetic ring in Beyerdynamic driver is truly something which comes under the spotlight.
Upon opening the driver came a observation of interest. This DT990 driver and that of my DT880 are exactly identical, including letterings on the side of the moving coil from what can be seen in the slit. The only difference is that the face of DT880 driver is pasted with a slice of relatively thick cotton fabric, while that of DT990 is a lot thinner.
After that, I gathered some of the nonwoven fabrics which came with previous CD purchases,
and cut them into similar shape of DT880 VR. I then stacked up 3 pieces for thickness imitation.
Subsequently, the headphone was reassembled for frequency response testing.
During the test, I made use of a strepitus scan with a higher degree of environmental adaptability. The curves would show diminishing effects, though they should not hinder comparisons.
Off the curves, we can see DT990 exhibits a great deal of resemblance to DT880. While it is true that some parts of the curves vary slightly, it is certain though such a material can absorb a wide range of frequencies for acoustic mimicking purposes.
(Some information enclosed herein come from the web.)