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wvdave wrote:

I see this project as enhancing the value of the property…

I also see this project to enhance a value of property. If I place in the mouth of my midbass horn some kind of MF/FM driver then I will be able to present my room as so called in US “great room” with built–in speaker in the wall.

http://en.wikipedia.org/wiki/Great_room

The whole point is that my midbass horn will be built in the pace that is NOT being used currently. In fact I might cover the horn’s mouth with cloth (or drywall) and no one will know that the horns are here. So, I feel that since the horn do extend the useable space of property then I feel that they increase the value of the property.

wvdave wrote:

Back chamber volume adjustment intrigues me, but I am called towards multiple adjustment systems rather than a one time deal and hence my ideas are overcomplicated and unsuitable for your installation. The plastic pipe thing w/the rubber seals is possible as I have a piece which will accept a 4" pipe sliding into it. The other end is threaded and can be worked into a mounting flange which will then bolt to a block of wood as the baffle. I use it as a light shield w/cap on a telescope project I have. The entire telescope mount is 1 1/2" galvanized pipe and allows rotation thru 3 axes, as well as solidity.

Your idea to use multiple smaller displacements in back chamber is a way reminds me the Control Rods for nuclear reactors - I will call this concept – Nuclear Back Chamber. That would be great if a high precision is necessary but I feel that it is not.  However, thinking further about the Nuclear Back Chamber I relapsed that this concept would allow to make an absolutely universal Back Chamber tuning mechanism and what is the most remarkably to make it very very cost-efficient.

I spoke today with my machinist and it look like if I will make the displacement piece of 20”  pipe then there are very limited  chose of materials I might use.  It would be primary metal pipe but I would like to have a material that will have the similar speed of sound in itself as wood.  Also, I need to have a long thread on the displacement piece as I do not know the approximate volume of my aimed back chamber. However, if to combine all problems together and to employ a Nuclear Back Chamber idea then here is a design that would address all problems. I would call it Culminated  Nuclear.

The Culminated  Nuclear Back Chamber imply that the rough adjustments of  Back Chamber volume takes place with expendable hard-solidifying foam (it is easy to cut it off with knife after it is hard). The there is threaded plastic cylinder of smaller size (let say 8”) that displaces the last few cub inch, tuning the Fs to it final settlement. I think to find a small 8” plastic sewer pipe, cover it and fill with sand will not be a problem. I like the idea as it is very versatile. If the extrusion of pipe is not enough then more volume will be displaced by foam….

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