Hi,
I recently completed my first passive radiator woofer. It's intended for the effects channel. It uses the 12" Peerless XLS woofers and matching radiators and uses Peerless' specified cabinet volume. What may be of interest is the construction technique. There are two pair of woofer-radiators each in their own volume with the two drivers and two radiators on opposing sides to cancel momentum transfer to the box. The box volume is divided along one of its main diagonals by a solid vertical shelf brace. Two other vertical shelf braces run from the other two corners and butt togetner at the same point (length center) along the first vertical brace and perpendicular to it. Each of the four resulting right-triangular cylindrical spaces has two right triangle horizontal shelf braces spaced evenly spaced along the vertical axis. These horizontal braces have the centers of their bases cut out to accommodate that portion of the speaker or radiator which they surround. All braces are highly perforated except the one long vertical shelf brace.
3/4" MDF is used through out. Using a shaper and the appropriate cutter I milled 90 degree points on the ends of the vertical braces that fit into the box corners. All pieces were cut to an accuracy of +- 0.5 mm allowing me to assemble the entire inner structure first. This was done in two glue-ups. The basic method of construction is biscuit joinery with high viscosity epoxy. Biscuits are intended to swell into their slots when the water-based glue is applied. But MDF won't take much expansion pressure perpendicular to its surfaces and it's sensitive to water. That was the reason for the epoxy. I choose a slow cure high viscosity epoxy so it would stay in place during the rather long glue-ups as it was important to keep the slots full until cured (since the biscuits don't swell using epoxy).
Attaching the top and sides included the use of biscuits along all edges and screws to reinforce the box at the top and bottom edges where the speakers are closest to those edges. Screws were also used to help clamp the top and bottom to the X shape of the vertical braces. To recieve the screws I used lengths of 3/4" square, radially sawn, hickory screwed and glued (with polyurethane glue) along the sides of the edges that needed screws. As the last step of the final glue-up screws were driven into pre-drilled holes in these pieces of hickory.
The speakers are front mounted and the deep grills, which surround them, were made using box joints. The exterior is covered in Formica and my original plan called for a granite top, but I fainted when I got a price quote for it, so I settled for glass.
eStatic.
(BTW the image was balanced on a LCD screen and looks kinda c... cruddy on CRTs.)
I recently completed my first passive radiator woofer. It's intended for the effects channel. It uses the 12" Peerless XLS woofers and matching radiators and uses Peerless' specified cabinet volume. What may be of interest is the construction technique. There are two pair of woofer-radiators each in their own volume with the two drivers and two radiators on opposing sides to cancel momentum transfer to the box. The box volume is divided along one of its main diagonals by a solid vertical shelf brace. Two other vertical shelf braces run from the other two corners and butt togetner at the same point (length center) along the first vertical brace and perpendicular to it. Each of the four resulting right-triangular cylindrical spaces has two right triangle horizontal shelf braces spaced evenly spaced along the vertical axis. These horizontal braces have the centers of their bases cut out to accommodate that portion of the speaker or radiator which they surround. All braces are highly perforated except the one long vertical shelf brace.
3/4" MDF is used through out. Using a shaper and the appropriate cutter I milled 90 degree points on the ends of the vertical braces that fit into the box corners. All pieces were cut to an accuracy of +- 0.5 mm allowing me to assemble the entire inner structure first. This was done in two glue-ups. The basic method of construction is biscuit joinery with high viscosity epoxy. Biscuits are intended to swell into their slots when the water-based glue is applied. But MDF won't take much expansion pressure perpendicular to its surfaces and it's sensitive to water. That was the reason for the epoxy. I choose a slow cure high viscosity epoxy so it would stay in place during the rather long glue-ups as it was important to keep the slots full until cured (since the biscuits don't swell using epoxy).
Attaching the top and sides included the use of biscuits along all edges and screws to reinforce the box at the top and bottom edges where the speakers are closest to those edges. Screws were also used to help clamp the top and bottom to the X shape of the vertical braces. To recieve the screws I used lengths of 3/4" square, radially sawn, hickory screwed and glued (with polyurethane glue) along the sides of the edges that needed screws. As the last step of the final glue-up screws were driven into pre-drilled holes in these pieces of hickory.
The speakers are front mounted and the deep grills, which surround them, were made using box joints. The exterior is covered in Formica and my original plan called for a granite top, but I fainted when I got a price quote for it, so I settled for glass.
eStatic.
(BTW the image was balanced on a LCD screen and looks kinda c... cruddy on CRTs.)
That's odd. Being new my posts are delayed till it's determined that I'm fit to be here. (I'm really not, but if I work real hard at it I can probably pass.) They do let me view my post once after the initial posting. When I did the image was indeed appended. And I assure you there was nothing the least bit naughty or untoward about it, and it was < 34 KB in size.
I will try again.
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I will try again.
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Timn8ter wrote: " The sub is beautiful but the rams are exhibiting violent behavior."
Thanks...I think
And Therac writes: "Very nice job! It has a high WAF!"
Thank you too. And I have to give my wife a plug here. When young she sang with some pretty decent a cappella groups and loves music almost as much as I. She has been wonderful about my passion for audio throughout our marriage. BTW: That is carpet* on the wall. It covers every wall of the media room and she helped me design the pattern, cut the carpet, and glue it up.
*Safety Warning: May be a fire/smoke hazzard.
eStatic
Thanks...I think
And Therac writes: "Very nice job! It has a high WAF!"
Thank you too. And I have to give my wife a plug here. When young she sang with some pretty decent a cappella groups and loves music almost as much as I. She has been wonderful about my passion for audio throughout our marriage. BTW: That is carpet* on the wall. It covers every wall of the media room and she helped me design the pattern, cut the carpet, and glue it up.
*Safety Warning: May be a fire/smoke hazzard.
eStatic
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