Headphone Heights

RE: Why do headphones have a jagged top-end roll off

72.37.248.39

This Post Has Been Edited by the Author

In Reply to: RE: Why do headphones have a jagged top-end roll off posted by Frihed89 on March 04, 2014 at 00:02:10

The physical problems are somewhat different from speakers.
In a headphone you are in the 'near field' for nearly all frequencies, i.e. the distance from driver to ear is less than the wavelength of the sound.
The active size of the driver is about the same diameter as a tweeter so clearly that's as small as you need to get for 20 khz.
You don't really need multiple drivers for radiation pattern purposes as you do with a loudspeaker. And then with the bass, you don't need to have very different physical requirements for the woofer as you don't have to drive anywhere near as much power through it. So some of the requirements which drive loudspeakers to multiple drivers aren't present with headphones.
In effect I believe that the physical construction of the drivers end up generating higher frequencies from a smaller area than the lower frequencies.
Most conventional drivers look as follows:
http://www.innerfidelity.com/content/very-important-sennheiser-hd-580-hd-600-and-hd-650-page-2
It's not obvious from that picture, but I opened up my HD580 (looks like "Current HD600"). The center of the driver, inside the ring of the coil, is actually a 3-dimensional dome facing outward, i.e. just like a tweeter with about a 2 cm diameter.
That part goes directly into the ear through the apparatus in the upper line, the center which is open.
The outer parts of the driver go through the larger circle which is covered with the white part, I guess I'd call that a 'midrange'.
Then finally bass frequencies probably get transmitted mostly through the resonance with the entire cavity and propagate through the whole of the white oval.
So to some degree, headphones might already be "multi-way" but accomplished by acoustic and physical means.

Edits: 03/06/14

Follow Ups: