The NaO U-frame woofer system is an excellent compliment for any smaller
speaker or speaker with challenged low frequency response. At the right the
NaO U-frame woofer is shown with the Quad 63 ELS speaker. In such an
application not only does the woofer provide deep, articulate bass response
but also unloads the main speaker from low frequency duty resulting in
improved midrange clarity and definition. The NaO U-frame woofer system is
also an ideal companion to the Magnepan MMG speaker system.
The NaO U-frame woofer system consists of an active, stereo
crossover/equalization unit which provides the necessary transition between
the main speaker and the woofer, and also provides the necessary
equalization to extend the woofer's response to 25 Hz. The system is built
around the Peerless 10" XXLS 830843 woofer. This woofer 25 Hz fs and Qts
sufficiently close to 0.5 (Qts = 0.44) make it suitable for very straightforward
equalization following the approach discussed in the section on Gradient
Woofer Equalization, for Qts of 0.5 or greater with acceptable fs. For this
application the 4th order high pass response was chosen insuring protection
from over excursion due to excessive equalization below fs when other
equalization approaches are implemented. This, combined with a quasi 4th
order Linkwitz/Riley crossover between the main speaker and the woofer
provide a seamless transition.
The NaO U-frame woofer system is sold as a DIY project in several formats:
plans plus the require printed circuit boards (PCBs); plans with assembled and
tested PCBs; or plans with completely assembled active crossover. The PCBs
used are the same as those used in the Mini active crossover. The
construction of the U-frame is left to the builder being the most cost effective
approach. The plans include complete U-frame construction details including
the required damping.
The NaOTM U-frame Woofer system
By Music and DesignTM....