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A more accessible source or two

Not everyone has access to the AES library, so let me cite something that's more readily available.

Addressing the issue of multiple low frequency sources vs a single low frequency source, Earl Geddes (a physicist specializing in small room acoustics and consultant specializing in loudspeaker design) wrote this in a Speaker Asylum post on October 30, 2005:

"At a single point in space, one can EQ the response, of course, but that has been shown to actually make the problem worse at other points, so it is not a global solution. To some, like myself, it is not a solution at all. The spatial variations, and to a certain extent the frequency response variations, will go down (get smoother) as 1/N, where N is the number of independent sources. In your example above the main channels having two woofers and then two subs goes a long ways towards a smoother response, about 1/4 the variation or four times better than one sub."

So here we have a case made for the use of multiple subs (and four is probably approaching the point of diminishing returns). But, where should they go?

Below is a link to a very short (two page) informal paper posted by Earl on his website. This documents the difference between placing four subwoofers one in each corner, and four subwoofers randomly, in a rectangular room. The different colored curves on the graphs are for different listening positions. This is not an in-depth study but is useful as a comparison of symmetrical vs asymmetrical positioning.

As you will see, scattering the subs results in significantly smoother bass at each of the three listening positions modelled in the simulation.

Duke

p.s. - If you ever want to do some educational casual reading, do an "advanced search" of Speaker Asylum posts by "egeddes".

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