Loudspeaker Kit Designs by Dick Olsher

The BassZilla Kit Plans

Updated September 2006

The BassZilla is an ultra high-efficiency (95 – 98 dB 1W/1m) loudspeaker family designed by Dick Olsher to facilitate the ultimate listening experience with low-power single-ended triode (SET) amplifiers. Its primary reason for being is to coax the most enjoyable musical experience possible from full-range and wide-range driver technology. The BassZilla combines a high-efficiency, direct-radiator, bass module with a full-range twin-cone or wide-range paper driver that is operated in an open baffle as a dipole radiator. The BassZilla's 15-inch woofer provides the foundation for the full-range driver, not only sonically, but also physically, as the open baffle sits on top of the bass module.

Two incarnations or flavors of the BassZilla are described. Each design preserves the coherency of the full-range driver by operating it full range without any high-pass electrical filters. However, a passive EQ network is used to deal with the inevitable break-up modes of full-range paper drivers. The "plain vanilla" version uses the Fostex FE208 Sigma, and exclusive of cabinetry, its estimated parts cost is in the range of US$1,000 – US$1,100 per pair – depending on the quality of the crossover network parts. The cost-no-object version is based on the Lowther DX4, and exclusive of cabinetry, its estimated parts cost is in the range of US$2,700 – US$2,800 per pair – depending on the quality of the crossover network parts. Commercial sources for drivers and parts are given at the end of the kit plans. Note that Madisound Speaker Components now offers fully assembled crossover boards for both versions of the BassZilla, as well as all parts for the Fostex sytem. These are easy to build kits, suitable for even the Do-It-Yourselfer with minimal woodworking skills.

Note: The BassZilla kit plans for the Lowther full range were updated during October 2003 to accomodate the new production Lowther DX4. The Diamond Edition incorporates the superb Aurum Cantus G2Si ribbon tweeter as a super tweeter to refine and extend the treble range beyond 10 kHz. Both of the latest members of the BassZilla family utilize the DX4 as a wide-range driver over the range from 150 Hz to 10 kHz to protect it from bass excursions - an important consideration for a driver whose maximum excursion is only 1mm.

The Platinum Edtion was finalized in April 2004 and is based on the new (and affordable) Fostex FE208 Sigma wide-range driver. As with the Diamond Edition, the Aurum Cantus G2Si ribbon tweeter is used to fill out the upper octaves. The sound is transparent, vivid, and electrostatic-like in its clarity and resolution.The Platinum Edition

The June 2006 Edition includes the latest woofer recommendations for the BassZilla speaker family, while the September 2006 addendum describes an open baffle (OB1) implementation of the Diamond Edition, which is bi-amped. The OB1 also incorporates a new ribbon tweeter.

The BassZilla design concept breaks new ground in the deployment of full and wide-range drivers. The inspiration for the BassZilla came about because of past personal frustration and dissatisfaction with traditional approaches such as rear horns. The truth is that right out of the box, such drivers are unlistenable due to high-Q break-up resonances. I'll show you how to properly tame these resonances and obtain the smoothest sound possible from the Lowther and Fostex drivers. I'll also show you how to unleash these drivers' full soundstaging potential by eliminating boxy effects in the midrange. Gain many of the benefits of planar transducers by operating your full-range as a dipole radiator. The 33-page Kit booklet explains the design philosophy, and gives detailed schematics and guidance for the construction of the baffles and crossover networks. Frequency response and impedance plots are included. These are Dick Olsher's new reference in high-efficiency loudspeakers!