When I bought an Apple G4 Cube computer system a few years ago, I was intrigued by the clear round ball speakers and digital amplifier which came with it. Nice sound, but lacking in deep bass, as with all small computer speakers.

The first step in building was to cut a piece of wood to block off the holes in the top of the cube enclosure. The wood was covered with sticky-back foam to ensure a good seal. Another piece of wood was cut to hold the driver and electronics. It is about 1/4” smaller than the inside dimensions of the case, and wrapped with weather seal foam.

The electronics are on two circuit boards. One is the amplifier itself, the other contains the input and power jacks and a level control.

After an initial listen, the electrical crossover point was lowered two octaves from IBM’s settings. The H/K balls go much deeper than IBM’s cheap speakers in their monitors. A piece of carpet was added in the top and back side of the upper chamber, and silver paper was added to dress up the system and match the paint of the computer.

This makes a really good sounding system. This woofer is tuned to 34 Hz and produces sound down below 30 Hz. 25 Hz is audible at the keyboard without doubling. I have since picked up an Apple - H/K iSub, which is the intended subwoofer for the Cube and iMac, and this woofer beats it on low frequency extension.