[Russell Dawkins]

(not Phil Spector's)...or "Wall of Woofers" (WOW).

Call me crazy, but...

What I would like to see someone do, since I am not in the position to do it, is build a front wall (behind the main pair) pretty well completely filled with woofers mounted into the wall with their backs open to the room behind. Any one of a number of scenarios could work.

This has never been as affordable as right now with the 18" Goldwood woofer going for $50 each.

To preserve stereo in the bass, there might be an area in the middle without woofers, but covered with absorption. The screen could go here(!). If the woofers are edge to edge, 5 = 90", so an array 5 X 5 would be 90" by 90" or 7.5' by 7.5" and would have an inherent efficiency of about 108 dB/W, but much more with room gain, which should be substantial since the entire wave would be more or less planar and fill the cross section almost perfectly, even if the wall was 15' wide.
Duke, you could probably help with the calculation as to what the room gain would be. As I say, if the wall is 16' wide and 8' high, two matrixes of 25 woofers per side would completely fill it. For more modest systems, a 16 woofer matrix would do the trick (per side, of course) and be 106 dB/W efficient and have the overall dimensions of 6' X 6' each side. One small twist is the fact that they would have to be slightly staggered to fit between 16" stud centers, but that is allowed for assuming an 8' wall. For lower walls, of course, the 16 version would be about 6'6" vertically.

I've saved the best for last. Both the 16 and 25 woofer per channel versions would be an easy-to-drive 8 ohms per side and the cost for parts an amazingly reasonable $800 per channel for the small version and $1250 per channel for the 2 X 25 woofer set up. Can you imagine inviting an unsuspecting buddy over for a beer and an 1812 demo on your new set up, then you pull the cord on the wall to wall, ceiling to floor dark curtains behind your stand mounted Summas, Abbeys, Nathans, Alphas or Gammas to reveal the real reason they sound so  amazingly huge for such little guys.

That moment, and others like it, not to speak of the hours of genuine pleasure with at last having truly great (and I mean in quality) bass has GOT to be worth every penny of the investment.

You might be able to dispense with the cone midrange entirely and go with a large horn like the Oris or LeCleach or the 15 incher that Earl Geddes uses, and make it a two way.

With something like a modded Behringer DCX 2496 doing the crossover duties, you could experiment to your heart's delight with the range of 300 Hz on up.

So, what do you think...hmmm?

[*Scotty*]

Russell, it worked for the Doc but I think it might be a little dangerous.

Scotty

[Duke]

Russell, I'm not sure how to calculate the room gain.  It would be a lot. 

What you describe would probaby approximate a "planar source", and so could be called a "planar array".  Not the same thing as a planar speaker, a perfect planar souce would be an infiinte plane radiator.  In practice SPL would fall off very little with distance (in contrast with a point source and to a lesser extent a line source), and interaction with the horizontal and vertical room boundaries would probably be minimal. 

In general, the fewer and farther apart the modes in a room, the more those particular modes stand out.  The ear tends to average peaks and dips that are pretty close together, but it cannot do so if they are far apart.  Thus low-frequency room interaction typically results in audibly lumpy bass, but in the midrange and treble region where the room-induced peak & dips are bunched up close together the ears sum the reflections instead of hearing the individual peaks and dips.

Now if I understand correctly the system described would essentially be a single mode sequence system in the bass region, as only the front-to-rear reflections would have any significant energy in them.  I am not sure this would be a good thing, as that one mode sequence is likely to stick out like a sore thumb.  And while it can be equalized for a given listening distance, at other listening distances equalization will make things even worse. 

So I guess I'd have to say that I don't know whether this system would sound smooth or not, but I bet it would hit like an army of synchronized sledgehammers.

[Russell Dawkins]

Thanks for saving me from myself, Duke. You are a gentleman and a trooper.

I was actually somewhat serious about this - these woofer prices have never been so low, and I had always been curious about what a wall of woofers would sound like ever since I read about some "audiophile nut" (this was the implication) in Popular Electronics in the 60s, I guess. He literally filled his living room wall, and it was a big one, if I recall.

I had completely overlooked how the different rate of spl fall off with distance from the bass array would affect system EQ, given that the mid/highs would have to have different radiation characteristics.

Maybe then the best compromise would be a single vertical array, but at the aforementioned woofer prices, that would still be a cheap experiment. Four of these Goldwood 15s with an fs of 29Hz and Qts of 1.03 are $160: http://www.parts-express.com//pe/showdetl.cfm?&Partnumber=290-346

I'm guessing that with these numbers they would work as well, as would the 18" equivalent, in OB as IB.

Thanks again, Duke.

[TRADERXFAN]

I know I am resurrecting an oldie here...

I have been thinking about the double bass array.
One in practice here with measurements...  http://www.avsforum.com/avs-vb/showthread.php?t=837744

I see there was some talk about it a long time ago. However, I don't know if anyone has actually made one, heard one.

The key differences between what was described here and a double bass array:

A limited, and deliberately spaced array of woofers on the front wall, and matching array on back wall. The back wall is out of phase, and time delayed to cancel incoming wave...

No modes.

wikipedia (translated from german) has the diagrams and math for the spacing.

Needs hard, non lossy walls -gee a basement sounds pretty good!
Needs symetrical, parallel walls, ceiling.

Furniture that interferes with bass will partially compromise effect.

No room gain, so must factor in real extension.

Anybody out there done this?

Geddes (and prob others) argued that it would not sound spacious, and this would be subjectively poorer than his multiple sub setup.

-Tony

[decal]

Don't mean to bust your bubble,but 16 or 25 bad woofers=crappy sound no matter how you add it up.Have you heard those goldwoods?I have,thet don't sound good at all.Just my 2 cents worth of useless opinion.