Harman Kardon HK-50 Omnidirectional Loudspeaker System

This is an interesting but small speaker system marketed in 1969. It is 11-3/4” by 11-3/4” and 18-1/4” high and weighs 22-1/2 pounds. This little gem radiates all reflected sound. The 8” woofer and 2-1/2” cone tweeter face upwards into a specially contoured Styrofoam cone shape. The sound radiates from all four sides. The top, although appearing to have a round grille in the center, is actually solid wood, perhaps for decorative purposes.

The Styrofoam reflector is held in place with two pieces of wood stapled to two wooden blocks. Note the extra contour in the right rear of the Styrofoam. This is located above the tweeter. The apex of the cone is about 4-1/2” above the base. Although the 8” driver is located off center in the cabinet, the apex of the cone is in the center of the cabinet.

Each side of the wood-frame grille has four large openings of equal size. The material is made of multiple-layer plywood and over the years has separated.

Some of the thin laminates were rattling around inside when I received the system. There is no indication of which side is the front but judging from the terminal location under the cabinet, the bottom of the above picture is the rear of the cabinet. The system is a sealed type and the drivers are sealed in place with Mortite that is now as hard as a rock. Even the mounting screws are covered.

The terminal plate is located in a corner of the bottom of the cabinet. The speaker terminals are either screws or an RCA phono type socket. System impedance is 8-ohms. An adjustable brilliance control is for the tweeter level.

Unlike the Eico HFS-2 and Citation X that have a closed back to allow placement against a wall, this system must be placed away from the wall or other reflecting surfaces. However, it is this very requirement that creates an advantage of better sound distribution. First listening to the system revealed a very spacious sound but the low frequencies were very limited by today’s standards. A review of the HK-50 was published in the June 1969 issue of Audio magazine.