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These are exactly the same as the Titanic MKII version except in Walnut cabinets and use the Dayton Series II driver. This driver does not match the Titanic in performance but it's definitely not a bad choice for the money. Another really good choice is the 12" XLS from Peerless. I don't like the DPL-12 so much in this application due to higher distortion above about 50 hz. The DPL-12 is however a great choice for sealed box subs especially in applications where it will not be used above about 60 hz. One thing to note about the DPL-12 is that below 50 hz it's distortion is lower than the Titanic MK II, and the XLS so if you are planning to use it only for below 50 - 60 hz then the DPL should be the best choice.
The total width of the cabinet is 13.5" not including the base or top hat width. Given that the side piece width is 15.5" you can deduce that the top, middle support, and bottom are also 15.5" front to back but make note this will include room for a trim piece on the side panel edges. Actually these pieces are 14.5". Also given the 13.5" total baffle width, and the .75" thickness of the MDFyou can deduce that these same pieces are 12 + 2 times the dado depth. If your dado cuts are 1/4" then these will be 12.5" x 14.5". The angled dados where the actual baffles sit are 60 deg. Keep in mind that the exact dimensions are not really that critical. The woofer has to fit and the total depth and width of the baffle should be kept about the same however. Also, I wouldn't suggest building a baffle such that the opening area is smaller than the woofer cone area. The peak in the frequency response seen below is largely a function of the baffle. If the air path from cone to the outside world is constricted stored energy will cause peaks in the response. Acoustically the best baffle would probably be one that does not sit the woofers at an angle like this one does. If you leave them firing directly forward peaks in the response should be reduced. The draw back is of course the cabinet must be wider.
Assembly: Pretty much all the joints use dado cuts. This takes a little more effort during parts cutting but it really makes assembly go a lot easier. It's worth it! The woofer baffles are set at approximately 60 deg angles. They are offset so as to allow easy mounting. Note that on one side the offset is about 3.25" and that it is only about 1/4" on the other side.
The side pieces are cut 15.5" wide by 29" high as shown above. The total depth however will be 16" due to a 1/4" trim piece to cover the MDF edges of the sides. This trim piece is cut in an "L" shape so that it wraps around the inside edge of the side piece.
The trim piece is cut so that it covers the 3/4" width of the MDF. The other leg of the "L" shape is also 3/4" and wraps around the inside edge of the side. The top, middle, and bottom of the baffle are 14.5" while the side piece is 15.5". This allows space for the trim piece.
The base is composed of three layers of MDF. The curve at the front was cut with an ordinary plunge router using an extended circle guide. Basically I just mounted the guide on a board with a pin at the far end to make an extension for a larger radius than the circle guide could normally make. These required a lot of sanding and filling using Bondo.
Almost finished, the top is covered by a top hat. The grill frame is cut with a similar curve as the base but with a slightly shorter radius to match it's recessed location relative to the front of the base. Perforated metal is used to cover the frame to hold the grill cloth in the curved shape.
Near field frequency response with no cross-over or compensation.
The standard Phoenix cross-over on Siegfried's web site is ideal for this woofer. Using Siegfried's detailed information you can make adjustments to the cross-over to fine tune the dip required to remove the peak in the woofer's response. Or, if you build the baffle such that the woofers are not at an angle then you might be able to omit that section of the cross-over entirely. Since the Q of the Dayton woofer is lower than the woofers in the Phoenix you may want to consider building Siegfried's correction circuit for this. He offers a board especially for this.