enclouser shape?

[dallaire]

Hello. I have just finished my ported test enclouser box for my Peerless 6.5 inch woofers. The test box is rectangular, for test purposes. I am making a cylinder enclouser now for the finished box. It also has a sphereical interior end, like a dome. I will be making four of these tubes. Two for woofers and two for the mids. They will be placed in a conventional looking box of one inch MDF, so from the outside the speaker will appear to be just your typical speaker in dimensions. What my question is, am I just going through a lot of trouble for nothing? making these strange enclousers? I am using fiberglass resin to form the spherical ends inside the concrete form tubes. I have read these odd shaped enclousers will yield a better response or less coloration, has anyone tried this approach? I will measure this against the test box when I am done, the test box mesured in room with floor bounce plus or minus three db.
Thanks,
dallaire

[Andy G]

The problem with cylinders is that you have the same distance in every horizontal distance for the whole length of the pipe.. ie a single standing wave resonance frequency.

I read of a work-around somewhere that used a heavily padded 1" dowel right down the centre. No idea if it would work or not, but the logic seems sound. ;-)

[dallaire]

Yes I was concerned about the one standing wave situation also, that is why I decided to make the interior "rear" of the enclouser a "dome" shape so the back would in fact not be flat but instead curved with the intent to even out the frequencies of standing waves instead of having one frequency associated with the length. I read at some site where they compared enclouser designs with frequency response and the cylinder and sphere seemed to produce the lowest response fluctuations per there findings. I think somewhere in the loudspeaker design cookbook there was something to this effect as well if I remember correct.
dallaire

PS- about the dowel approach, was the dowel parallel with the cylinder or perpendicular??? I also was thinking about making the inside of the enclouser look like the inside of a anhoic chamber to kill all reflections and resonances, which is probably impossible anyway.