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.
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.
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.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
A big thank to Dave for all his valuable help,
Markus
Cross-over point 213 Hz/second order (happened to fit with the values). In the future I may bi-amp it.
Well my goal was that a symphony orchestra should sound like a symphony orchestra and a funk band like funk band without giving up details. I must confess that I’m satisfied. The alpairs also seems a bit happier without struggling with the bas.
Well my goal was that a symphony orchestra should sound like a symphony orchestra and a funk band like funk band without giving up details. I must confess that I’m satisfied. The alpairs also seems a bit happier without struggling with the bas.
"in the future I may bi-amp it" sounds to me like currently passive XO
Markus - gorgeous freaking work on the machining of interlocking aluminum coupling parts - glued to drivers' magnets , I guess?
Very creative, but far too complicated for me personally, I would have used a simple bolted flange. Very impressive build nonetheless.
jeff
The scanspeaks has the magnet attached to the frame by screws. I just extended them to go through the aluminum parts. I would not trust glue in the long run. There was some work with the aluminum parts, guess 3d-printing would be the easy way out.
If I understand Dave’s calculations right the box is tuned to 41Hz.
If I understand Dave’s calculations right the box is tuned to 41Hz.
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