[tyre]

While searching through the USPTO website for headphone related patents, I ran across a patent issued to AKG back in the '70's. It's titled "Headphone Operating on the Two-Way System". The patent describes a system in which an electret tranducer is used to reproduce high frequencies and a dynamic transducer is used to reproduce low frequencies. Sounds familiar...

The original images are in .tiff format that requires a browser plug-in to view, so I resized and changed them to .png format.













Here's the link to the USPTO page, click on the "Images" button at top for the original .tiff images.

http://patft.uspto.gov/netacgi/nph-P...&RS=PN/3943304

 

[wualta]

Cool! Just discovered this! Thanks!

 

[ej82m]

Nice find. Should be an interesting read.

 

[philodox]

Very cool... after I wade through the meet impressions I am going to give this a read.