The leads are then terminated to gold-plated solderable terminals located on opposite sides of the former to discourage rocking modes. Last, RMS power handling is rated at 200W and the voice coil tinsel lead wires are stitched into the spider. Driving the cone assembly is a 38mm (1.5”) diameter dual voice coil (two 4Ω coils) wound with round copper-clad aluminum wire (CCAW) on an aluminum former. The motor is an FEA-optimized dual-ferrite magnet type with milled plates and extended copper sleeve shorting ring (Faraday Shields) on the pole piece.
Compliance is provided by 21mm wide NBR surround that has a mostly shallow transition to the cone attachment, with the remaining compliance coming from a 4” diameter flat cloth spider (damper). The cone assembly consists of an extremely stiff curvilinear-shaped carbon fiber cone fitted with a 1.6” diameter carbon fiber dust cap. These disks also provide an 8mm space between the two 7mm gaps as well as a conventional cooling path for the voice coil as it travels between the two gaps. These magnets do not add flux to the upper 7mm gap, but rather act as magnetic “diodes” (aka gap balancing magnets) pulling the flux from the main magnet into the top 7mm gap. However, the secondary magnet system is comprised of six 28mm×8mm ferrite disks. The primary magnetic drive is provided by the 121mm×25mm ferrite rear ring magnet, directly providing flux to the second rear 7mm gap. Additional cooling occurs as a result of the MMAG multi-magnet configuration.
#Full range audiotest driver#
Photo 2: Close-up view of the Dayton Audio E150HE’s neck jointĪdditional cooling for this driver is provided by six 4mm diameter vents in the voice coil former, as well as three 8mm diameter vents in the back plate. The EP150HE has a substantial feature set that begins with a proprietary six-spoke cast-aluminum frame, composed of narrow (about 9mm) spokes, completely open below the spider (damper) mounting shelf for cooling (Photo 1 and Photo 2). The Dayton Epique E150HE-44 is promoted as a full-range subwoofer, which in itself is an interesting concept, and one that is ideally suited to the MMAG technology given the typical high-excursion/low inductance aspect of this motor design. Enrique is now an independent transducer engineering consultant and developed the two new Epique full-range subwoofers in conjunction with the engineering team at Dayton Audio. While the partnership is no longer together, Enrique is still developing MMAG woofers, the latest example being this month’s first driver to be examined the Dayton Audio Epique E150HE-44. Together this talented trio fielded more than 40 transducer patents, which is quite impressive. This partnership also included Richard Calderwood, a world-class patent attorney, who is currently the Director of Intellectual Property at Nvidia, and was the former senior intellectual property attorney for Intel Corp. In practice, this dynamic duo had Enrique doing a lot of the conceptualization and Patrick heavy into application. Step Technologies was originally a partnership between two of the best transducer engineers with whom I have had the distinct pleasure of working-Enrique Stiles and Patrick Turnmire (Patrick has done much of the Klippel LSI analysis that has appeared in this column). MMAG was invented by Enrique Stiles, and the MMAG patent (there are several) that applies to the E150HE-44, US6,917,690, was assigned to Step Technologies, Inc. Photo 1: The new Dayton Audio MMAG E150HE-44 full-range subwoofer
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