I got my headphones used, defected left channel. Those drivers had white layers in the capsule.
I ordered one from sennheiser and the new driver had black layer.
I'm not sure how all versions are identical.
Left Channel: old, driver, i'm not sure if it is old, new version or even HD600. On the sennheiser box, the date is 1998.
Right Channel: right, new driver (HD580)
The difference is small but noticable with ears
Is this acceptable and usual?
(and i replaced only the drivers, used identical left and right capsules)
I repeated this measurement and got the same results
So these drivers are mixed up, i'm not sure what kind of differences are in versions.
I'll end this calvary with sending my whole headphone to sennheiser.
One more notice: My left channel looks similar to Headrooms HD600' measurement:
My microphones are cheap ones, but differences are still evident..
Edited by angevoi - 11/16/12 at 2:31am