12" XLS in a 3.5 cubic sonotube?

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Anyone ever do a Sonotube type sub with a 12" XLS sub? I have two hanging around and would prefer to not have to purchase a passive set for them but would really like to get some good use of them. I've had them in a EBS cabinet before and liked the sound and output but they were too big for our living space back then. So I've opted to use 15" sonotube and build something within the 3.5-6 cubic feet or close to 36" tall tube.

Now if anyone has any experience with this type of sub with this driver I'd be very appreciative if you filled me in on the final outcome.... Peace and happy listening

Speaks
 

GM

Member
Joined 2003
No personal experience with this driver, but it's very stiffly sprung, so down firing sag isn't a problem. Obviously, mounting a PR isn't practical, so a large, long vent is required to tune it to near/at Fs. Since the longer the main tube is, the more TL loading it has, then making it near ceiling height dramatically shortens the vent if mounted in the top plus this loading scheme seems to provide a more enveloping bass experience than a typical low tuned sub.

In only a ~36" height though, the vent will likely need to be large, long, so under sizing it and tuning it with stuffing to make it semi-aperiodic will probably be required.

Note that HornResp can model the basic undamped design, then it's just a matter of experimenting with damping to find the best in-room response. FWIW, suspending a 1" acoustic 'blanket' down the center to quell the infinite number of cylindrical eigenmodes and offsetting the vent to allow it has worked well for me while others prefer to line the entire wall, which tends to over-damp them with the typical batting densities used in typical box construction.

GM
 
I have lots of sonotube experience with HSU subs, so with that caveat in mind....

4cu.ft with a pair of 24" long 4" diameter ports in a 18" tube tunes for 25hz. (26" interior dimension) One of the things you can do with multiple ports, is block one or more to change the tuning. AKA, you can have both ports open for music (25hz tuning) and then plug one with a piece of foam, to drop tuning for HT.
The SVS guys use 3 ports, just so they can block one or two, and have a total of 3 tunings.

For pvc ports and sub to all be downfiring, you need 18" diameter tube, 15 won't work. However if you want to be clever, and have access to some 12" (interior diameter) tube as well as your 15"... A pair of 4" ports is 25 sq.in. The difference between 12.6" O.D and 15" I.D. is 51sq.in. SO.. you mount your sub in a 24" long 12" diameter sonotube, slip that inside a 15" I.D. sonotube that will yield 26" interior dimension, and use 4 wood strips at 90 degree intervals, to attach the interior to the exterior tube. Block 2 of the openings, and you have the same port area, as if you used a pair of 4" diameter pvc ports. The 4 wood strips are also your cabinet legs...

Obviously, you can change port length/diameter very easily if you have one sonotube that fits inside the other, so take the above dimensions as example only...
 
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