The B-Hive Motor is the future of high output woofers. It's an elegantly simple design featuring "radially magged" high temperature Neodymium magnets surrounding an under hung  voice coil that's encased in a low carbon steel return structure. This allows the cone to have high excursion with the lowest possible distortion. In addition because the entire length of the anodized aluminum edgewound voice coil is always in the magnetic flux or B field, right up to the X-max limit  the Thiele-Small parameters don't change dynamically under various input power levels. This also means the amplifier can more easily control the coil. In addition the entire coil is intimate to steel so there is no temperature gradient along its' length and potentially damaging heat is wicked away through black body radiation. The shape of the motor was optimized using  FEA (finite element analysis)  inorder to dissipate heat, focus flux and reduce weight. We looked at the thermodynamics of the B-Hive Motor and choose the specific "crab trap" internal shape of the pot structure so that it forms an "air diode" which promotes convection cooling.  The air flows one way  when the  cone moves back and forth  pulling air through the motor. Heat is forced out of the pot structure and through the vents below the double spiders. Externally the ribbed exterior dramatically increases the outside surface area without adding much mass and acts as a heat sink promoting the action of radiating heat out of the motor. This further reduces the effects of steady state power compression caused by extreme input levels over long periods of time. The result is a woofer with more linear excursion providing greater acoustic output with ultra low distortion, quick transient response , lower power compression and very high linearity. Please note: No top plates were used in any of our testing and designs

• The CGN1808 subwoofer is 18" (460 mm) in diameter with a 4" voice coil (100 mm). It utilizes the B-Hive Motor for its magnetic circuit and it has Two inches (50.8 mm) of peak to peak fully linear excursion, and can move more than Three inches(76.2 mm)before damage. It is also produces no stray magnetic flux so it is inherently video shielded and can be easily shipped by air. It weighs 33Lbs. (15 kg). That's just a few pounds more than a conventional ceramic magnet pro 18"woofer but the CGN1808 typically has more than four times the acoustic output. It is extremely efficient and handles great amounts of power so use the biggest amplifier you can find. We currently make several versions of this subwoofer. One that's an excellent choice for a horn design features a Honeycomb Fiberglass Composite -----waterproof cone----- . Our most popular version utilizes a composite paper cone with the following Thiele-Small parameters:
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•  NomZ 8 Ohms, Sd .137 sq. m, BL 22.65 TM, Revc 5.23 Ohms, Vas 435 l, Cms 163 uM/N, Mms 207 g, Fo 27.4 Hz, Qms 23.5, Qes .363, Qts .357 Xmax 12.5mm fully linear 18 mm ( > 10% distortion 3rd. H.) 96.5 dB @ 1M 2.83V More pictures of the woofer are located at http://www.neodymiumloudspeakers.com. We also have cabinet design plans.
• Here are some quick cabinet designs from Leap.
  Quasi 3rd./Butterworth Vb= 7.25 cu. ft. fb = 30.34 Hz , F(-3) = 33.81 Hz , Peak 0 dB
  Extended Bass Shelf/ BW, Vab = 9.94 cu. ft. , Fb = 27.4 Hz , F(-3) = 28.84 Hz, Peak 0 dB
  Damped Chebyshev/Bessel Vab 8.53 cu. ft. , fb 25.1 Hz , F(-3)= 35.53 Hz, Peak 0 dB.
• Also in the design phase of your box please take into consideration that this 18" subwoofer is a few inches deeper (12") than most. The frame is a little larger diameter.  Technically it is really an 18.5" . PLEASE NOTE  this subwoofer moves a lot of air so we encourage the use of ports that are often twice the area of conventional norms. * Finally because the cone can move so far we reccomend at least 1.75" clearance from the front of the woofer to the back of the cabinet grille.
• CGN audio labs, 27 N. Wacker Drive, Suite 257, Chicago, IL 60606 PH 651-460-4783 FAX 707-597-4484 
•   email TGallagher@prodigy.net
• MADE in the USA