What’s stiffer, internal bracing or thicker sides???

You are describing a Single Bass Array ideally having significant absorption on the opposite wall, and the baffle wall is going to have to be considerably more rigid than studs and plasterboard to not have resonances slap bang in the range we don't want them! My very first flat-to-20Hz sub excited the solid brick wall on which the turntable was mounted to such a degree that uncontrolled LF feed back occurred with the stylus resting on static vinyl. Five inch drivers are no more 'dynamic' or 'faster' in the LF range than large ones - unless you mean simply that they can play higher frequencies - and considerably less efficient. The bass wall idea is very appealing and has advantages on many fronts (pun intended), and is something I have always wanted to build, but sadly the ideal room I was going to use (partly underground and with 800mm stone walls) has now been taken over by a CNC router amongst other things... Both Single Bass and Double Bass Arrays are rarely implemented due to the dedicated space required, so first-hand information remains rare, however on paper it is technically superior.

Wall of Bass

That Wall of Bass is not my I'm referring to.

I just want a "cabinet" that is measured not in liters but in cubic yards! Such an enclosure ( say 14'x8'x5') would measure out to about 20 cubic yards or 15,857 liters!!!! In essence, those woofers would operate as in an infinite open baffle, or into an infinite cavity.

The idea behind many small drivers would be to spread out the resonance of the driver into a large wall area, so that the resonances would be spread out.

Efficiency and speed? Well, many small, low mass drivers driven each by a 200 watt (or so) class D amp would be extremely dynamic and, with their low mass and high damping factor from the Class D amps, would have tremendous bass characteristics. For sure, it would not have an "over ripe" sound. And, 30x200 amps, and with the efficiency of class D, such power would be doable in a residential home with just two 20A 120VAC lines.

Space? Hey, this is so far a thought experiment, but a 14x8x5 storage room is not out of the question when you are looking at 2800+ sq foot homes.

Insofar as Costco survived the 2020 Toilet Paper Fiasco, such a room could easily be tuned with Kirkland toilet paper and assorted paper products... ;-)

Now taken to the extreme, you could install two 20 inch drivers that vent the room into the garage or outdoors. That would make the room isobaric, although at that point I think we're beyond being anal retentive.

However, more realistically, you could build a smaller baffle wall with those small drivers and then put those two 20 inch drivers vented to the garage, or elsewhere, via long tubes. Perhaps the attic? The basic idea here is to use the "sealed baffle wall" as the enclosure.

EDIT, I would not mount anything on that wall. Indeed, I would plan on having a poured foundation floor, that's how my house is build and my turntable sits on a Target 5TT stand on spike/cups onto the floor, which is on the foundation. The only time I get vibrations is when we get a quake, and then I'm not too concerned about acoustic feedback though the stylus, if you get the drift. ;-)
 
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You are describing a Single Bass Array ideally having significant absorption on the opposite wall, and the baffle wall is going to have to be considerably more rigid than studs and plasterboard to not have resonances slap bang in the range we don't want them!
Push-pull mounting would presumably help with this.

http://www.cowanaudio.com/

Mr Cowan's design decisions (see "Unity, the Finale" and "Infinite Baffle Sub") look good to me.
 
When I started this project, I was planning on buying two concrete sinks to use as cabinets but a friend gave me his wood cabinets which he built 35 years ago.


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Kelp88

Member
2007-06-26 5:00 am
I am currently building a pair of concrete floor-standing speakers (3 way). Concrete is much stiffer than wood, for a given thickness. With the panel sizes of the concrete sink I would probably still cross brace it. Also I will be adding damping to the interior of the concrete to tame the ringing of the high-performance GFRC I am using. This may not be as important in a sub-woofer application.

Ben
 
I am currently building a pair of concrete floor-standing speakers (3 way). Concrete is much stiffer than wood, for a given thickness. With the panel sizes of the concrete sink I would probably still cross brace it. Also I will be adding damping to the interior of the concrete to tame the ringing of the high-performance GFRC I am using. This may not be as important in a sub-woofer application.

Ben
Subs need stiffness, mids need damping. A decent sub enclosure should have the main resonances so far above the passband that they will be largely irrelevant.