Down-firing Subwoofer Placement

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Your friend doesn't know acoustics.


It is very difficult to absorb bass energy.


It requires materials and volumes of space that are on the order of a few feet in thickness.


An inch or so of carpeting vis-a-vis a sheet a plexiglass will have zero effect on the bass from your downfiring

subwoofer.

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Thanks. That makes sense, and by your signature it looks like you should know!

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jstorer,


Hardwood vs. concrete? In a word - no.


Hardwood floors have a tongue and groove construction so that they are fairly air-tight. In that matter, they are

like a concrete floor.


Let me tell you what would be different. Suppose you had a floor of 2x4s laid over the floor joists, and a basement

below. Because of the gaps between the 2x4s, that floor is not air-tight. Bass energy could flow through it into the

basement below - from whence it won't return. Such an arrangement would soak up bass energy.


That's what it takes to absorb bass - a "membrane" that it can diffuse through into a volume in which it will dissipate

without return.

While it is true that the carpet won't absorb the subwoofers bass, it is good at absorbing the occasional higher frequency sounds a subwoofers woofer might produce: suspension noises, bottoming, etc..


In general, we find downward firing on carpet makes a sub a little less localizable. This lets the sub get louder and push its limits and still remain less localizable.


If the subwoofer fires down on hard floor or a hard surface, these out of frequency noises are reflected easily and can make it more localizable.


For the same reason you would want to absorb first order reflections in main speakers, you would want to absorb out of frequency anomolies in subwoofers. By downward firing on carpet or a throw rug, you can absorb these sounds.


Plus, the carpet might absorb some unwanted vibrations so the flooring underneath doesn't vibrate and cause problems.


Sasha,

HSU Research