A piece of history:
The Sunfire True Subwoofer, designed by audio legend Bob Carver about 30 years ago, is a legendary piece of home audio equipment. It revolutionized the market by packing a massive 2,700-watt tracking downconverter amplifier and deep, room-shaking bass into a remarkably compact, roughly 11-inch cube.
The cabinet uses a unique push-pull design housing two 10-inch diaphragms—one active and one passive. This allowed the tiny cube to move massive amounts of air.
It can reach astonishingly low frequencies (down to 18 Hz) that were previously thought impossible without a refrigerator-sized subwoofer.
Carver utilized specialized high back-electromotive force drivers, which allowed the small enclosure to perform with tremendous authority and low distortion.
This was the first miniature high-end subwoofer that inspires subwoofer design to this day.