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Subwoofers - Front Firing or Down Firing - Which Sounds Best?

Any advantage to woofer cone facing toward listener as opposed to firing down to the floor? Thinking of upgrading my 20 year old B&W ASW-650 sub to get that oh-so-pleasing belly message which lives in the 20-ish Hz range (very rare I know). SVS has the "tube" subwoofer (PC-2000) at a reasonable price. Just wondering if the floor-firing model would disappoint? Wouldn't want the hassle of returning if it did. Any opinions? Current users? Thanks. 
128x128dweller
bdp24's avatar
bdp24
9,788 posts
 

Rythmic Audio used to offer a down-firing sub. Designer Peter Ding found it to be inferior to all his front-firing models, and discontinued it.

In talking about the wavelength of bass frequencies, remember: the lowpass x/o filters are not brickwall. If you are using a 1st order filter at 80Hz, the sub is down only 3dB at that frequency, and 6dB at 160 Hz. That is clearly audible, and will effect one's perception of the sub. The steeper the filter and lower the x/o frequency, the less will you hear the sub above the low bass.

dweller's avatar
dweller OP
3,781 posts
 
I'm pretty sure a single 15-inch SW will give me what I want. But being retired, cost is a consideration. In my smallish (12 X 13) room, I could use the tube SVS as a plant stand and it doesn't take up much room (as well as being affordable). Thanks to all for the replies! 
jon_5912
605 posts
 
Sound travels at 1125 feet/second per Wikipedia. That means wavelength is 56 feet at 20 hz and 14 feet at 80 hz. Resonances are caused by reflected waves reinforcing the direct wave. If your room has, say, a 37.5 foot dimension, expect to have a peak at 30 hz, 60hz, and possibly higher multiples of the resonant frequency.

When I was in my twenties I bought a real time analyzer and measurement mic so I could test the calculations. In that period I upgraded from B&W N804s to B&W N802s. That was a change from a front port to a down port. Since the port output is at subwoofer frequencies I consider this a reasonable comparison. The 804s had atrocious in-room measurements. They were actually flat at 20hz. All over the place from 20-100hz. 30db swings in my room. The 802s measured far, far better in the deep bass. They were actually very close to the published spec. They hit the -3db point at almost exactly the published point and the overall deep bass measurements were far smoother. The only plausible explanation is that the down-firing port doesn’t excite resonances to nearly the same degree as a front-firing one. Which means direction matters, even at very low frequencies.

freq/length in feet
20 56.25
30 37.5
40 28.125
50 22.5
60 18.75
70 16.07142857
80 14.0625
mapman's avatar
mapman
22,199 posts
 
Nix the down firing. That produces the most floor interaction which muddies the bass and obscures the midrange most especially with the suspended plywood floors found in most modern construction homes.
geoffkait's avatar
geoffkait
23,365 posts
 
I built downward firing 4’ high cement cylinders with 8” drivers mounted in the bottom, raised four inches of the cement floor. Awesome sound, like cannons going off. Tighter than a bull’s you know what. 🐂 The back wave reinforces the motion of the sub.

Tip for the day: never move into a place with suspended wooden floor where your hi fi is going to be. Think ahead. 
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