Above are the new Zen Open Baffle speakers.

As a continuation of (PART I )we have constructed a pair of these speakers based on the latest design that uses the more complex resonant cavity. The results greatly exceeded our expectations that were set by the first drywall prototype.

Because of the dominant hole in response between the driver and the cavity the original prototype was too handicapped to be listened to by itself. When the cavity was miked and or a subwoofer was used and crossed over above 100 Hz, the speakers sounded well balanced.

In the new design, the hole in response has been eliminated and the tuning of the cavity did not have to be raised. This was a pleasant surprise. It was hoped that the new cavity design would lessen the severity of the hole, but that it worked so well was unexpected!

TESTING>

The first step with these was to become familiar with them on their own, no subs or fancy broadcast setup for the resonant cavities. I sat down expecting to hear basically zero bass and that was OK because I really wanted to hear if we got the textures in the midrange right. Remember the cavity is primarily to open up the sound of the midrange and support it with compatible harmonics. Shutting the adjustable slot below the driver confirms that placing a driver in a plane board is a dry almost lifeless sound by comparison.

As I started to listen I was immediately taken by what I heard. In fact I got so swept up in it that it was probably 10 minutes before I remembered that I was suppose to be listening to a speaker with no bass. Since I was listening to acoustic music there wasn’t a lot of bass in the recordings and I remember sitting there thinking that what I was hearing sounded simply great, not thin at all. About then a tympani drum was struck in the recording I was listening to and I felt the percussion of it in my chest. Now wait a minute - I thought… as I started to double check all the other gear in the room to make sure I hadn’t somehow accidentally left a sub on somewhere.

Read the entire paper ( HERE ).