Some time ago I built my first speakers based on alpair 7 and modified pensils. They sounded very good but after a while a started to want a little improvement in the bas region and it also seemed that it missed a lot of detail when there was music with more bas. However there was a lot that I liked with the alpairs so I decided to give them a little help with some woofers.
With the kind help by Dave Dlugos we decided on scanspeak 18WU/8741-T00 in a push-push configuration and a 46L vented enclosure with the alpair in a aperiodic transmission-line about 5-6L.
I built it from inside out. After constructing the t-l for the alpair I made the bracing and a frame. Over that I laminated two layers of 4mm birch-plywood (vhv), after that a 8mm board used to damp floors, after that plywood (hvh) and last mdf. It turned out to be a very stiff construction without any vibrations even when playing very loud.
[IMGDEAD]http://i43.tinypic.com/33tkufa.jpg[/IMGDEAD] [IMGDEAD]http://i39.tinypic.com/xddti.jpg[/IMGDEAD] [IMGDEAD]http://i41.tinypic.com/zxjz1j.jpg[/IMGDEAD] [IMGDEAD]http://i44.tinypic.com/b3rf5g.jpg[/IMGDEAD]
One technical challenge was how to fix the elements to each other to get the most of the push-push configuration. Obviously it has to be done when the elements are in place and a hole would not be a satisfying solution. I decided to do aluminum pieces that I could attach to the elements and that would click into each other. It turned out to work very well.
[IMGDEAD]http://i42.tinypic.com/219aix.jpg[/IMGDEAD][IMGDEAD]http://i39.tinypic.com/2j4poqx.jpg[/IMGDEAD]
A big thank to Dave for all his valuable help,
Markus
With the kind help by Dave Dlugos we decided on scanspeak 18WU/8741-T00 in a push-push configuration and a 46L vented enclosure with the alpair in a aperiodic transmission-line about 5-6L.
I built it from inside out. After constructing the t-l for the alpair I made the bracing and a frame. Over that I laminated two layers of 4mm birch-plywood (vhv), after that a 8mm board used to damp floors, after that plywood (hvh) and last mdf. It turned out to be a very stiff construction without any vibrations even when playing very loud.
[IMGDEAD]http://i43.tinypic.com/33tkufa.jpg[/IMGDEAD] [IMGDEAD]http://i39.tinypic.com/xddti.jpg[/IMGDEAD] [IMGDEAD]http://i41.tinypic.com/zxjz1j.jpg[/IMGDEAD] [IMGDEAD]http://i44.tinypic.com/b3rf5g.jpg[/IMGDEAD]
One technical challenge was how to fix the elements to each other to get the most of the push-push configuration. Obviously it has to be done when the elements are in place and a hole would not be a satisfying solution. I decided to do aluminum pieces that I could attach to the elements and that would click into each other. It turned out to work very well.
[IMGDEAD]http://i42.tinypic.com/219aix.jpg[/IMGDEAD][IMGDEAD]http://i39.tinypic.com/2j4poqx.jpg[/IMGDEAD]
A big thank to Dave for all his valuable help,
Markus