Mini-aechoic chamber - loudspeaker testing
I couldn't see a discussion on this topic in the forum already and I thought this part of the forum would be the best section to put it in so here goes.
I have an idea - purely formative at this point - of creating a reasonably sized anechoic chamber that would allow the tester to measure a speaker with a reasonable degree of accuracy in the near and far field in-situ. I know there will be some compromises over a full-blown outdoor measure (or a real test chamber for that matter) but I am thinking of a portable chamber comprised of 2 half cubes that when assembled might be 1 metre cubed. I got the idea from some websites selling transportable recording booths. It's a similar principle I believe. If you can make a sturdy structure that is finished in multiple layers of acoustic material then you could conceivably reduce reflections to a negligible level. For example, if you used an expanded aluminium sheet or perhaps a framework of acoustic fibreglass panels to form a shell then from than coat it in layers of acoustic foam then you might be able to get an NRC of a high value at low frequencies. Sonex for example posts graphs that show successively thicker layers of the material attenuating lower frequencies to a greater degree. I would think that a sensible limit might be around 250hz for the far-field attenuation goal. Nearfield could be done with 1 side of the cube in front of the speaker to limit direct reflections. I would suggest a small aperture to base of the cube to allow the mic stand to go through and another medium size aperture to allow the speaker stand to go through.
So, is this a dumb idea? Has it been thought of? I just thought I'd throw it out there to see what reaction I get.