Project #2 - Documentation for Quadraphonic Headphones

Probably the most unique aspect of my headphones is the housing, a foam cover intended to keep outdoor water faucets from freezing in the wintertime and seldom used in the Austin area. While available in the months of December and January, they become rare after that timeframe. No longer on the shelf, I had to ask a store clerk for them in mid-February when I first thought of this as a project which was originally intended for my project one. I bought 4 just in case I messed one up. Another shopper asked if I was expecting another freeze. My explanation of quadraphonic headphones did not help my status with that inquiring mind!

The original headphones are Koss 727 and Koss Pro4AA units dating back to the 1970s. (Nothing wrong with the '70s!) I decided that the foam as too soft to support a headband and its associated adjusting movements. Rather than risk breaking one during the project demonstration or by a listener in the ACTLab, I left the cable between the two sets of headphones as they were originally. (The 727 wiring had already been replaced.) This allowed the quadraphonic pair to nearly rest on a listener's head without support other than from the cable.

I used silicon sealant to hold the transducers in place and to close all of the holes assuring each transducer individually and the whole system to remain closed.

There is a bit of a chamber inside the foam cup behind the transducers. I considered filling the back side of the transducer housings with fiberglass or other damping material, but I was not sure how to keep it stable and not get into listener's ears. Therefore, it remained hollow. I am not sure what affect it may have on response.