The overall enclosure design for this speaker is fairly straightforward; the external dimensions are 12" wide, 12" deep, by 76" tall. This is separated into four distinct air chambers: one for the tweeter, one shared for the midbass drivers, and one for each subwoofer. Note that the 12" width is definitely the absolute minimum that could be used for these drivers; I had to do some extra fi nagling to make everything fit.

The subwoofers each have their own airspace, which runs approximately 23 inches up into the main cabinet and ends just below the midbass drivers. The walls for the subwoofer section are made of dual layers of 3/4" MDF for rigidity. An internal partition separates the upper and lower woofer airspaces into roughly .45 cu. ft. net per woofer, which is ideal for the HO subwoofers.

One important feature of this cabinet is a removable rear panel. I don't normally do this on my speaker designs, but because of the rear mounting that the RD50 requires it is a must. Serviceability should always be kept in mind when designing any speaker-whether it is for the drivers or the crossovers. As such, the subenclosure for the RD50 is just wide enough to physically fit the steel housing, and runs the full depth of the cabinet for access through the removable rear panel.

The other half of the upper cabinet is a single large enclosure that the midbasses share. The net volume for all of the woofers is about 1.35 cu. ft., or about .17 cu. ft. per woofer. This is suffi cient for an overall Q of .7 for the midbasses, with an F3 of about 95 Hz.