I posted about this subwoofer project earlier this year with some pictures of the construction and a description of an idea for a closeable port. So I went on a journey to have a Port Valve turned from Oak. Well the guy who was going to do the turning gave up on me so I went and bought a lathe and did it my self. I’m actually glad I got the lathe, beside it being a lot of fun I was able to get the valve just the way I wanted it and the valve seat fits so tight that I will only need a thin gasket to finish the seal, so I’m very happy with the functionality of the entire Vale mechanism, it works very smooth and only a few twists of the knob and the Valve is closed very tight.
Besides the 5 month delay to get an acceptable Port Valve turned the project so far has taken about 300 hours over 4months and cost about $1200 US for each of the 2 Maelstrom 18” Sonotubes. I still have a few details to finish but this one is ready to go into the listening room. Next I will silkscreen the plate behind the Valve knob with a placard that will show the “Open” and “Close” position, and a felt gasket on the valve seat to complete the seal. The prototype worked very well so I’ve already had many hours to listen to a working version of the port valve in a real world situation, and it does work very well to tighten up the bass when the valve is closed, pulse it’s somewhat decorative and functional as a display shelf. Now all I have to do is fix all the rattles in the house that just one of these has brought to my attention. Hopefully early this New Year I will have both subs in the listening room and have the BFD E.Q. set up properly.
Here is a link to another site that the pictures are posted at.
http://www.diyaudio.com/forums/showt...421#post292421