I have finally got around to accomplishing a much needed sub system upgrade. My present sub is a DefTech Supercube Reference. The Cube is a quality sub for movies and music, though one by itself can't come close to reference level in my room. I debated for quite some time and decided to go the DIY build route instead of buying another Supercube.
My rooms dimensions are 18ft x 19ft x 8ft. The room is totally sealed, no windows. It has four closets built out into the room to hide my extensive movies and music collection along with wire and cable, tools needed and an assortment of sound, light and electrical meters. It has an equipment rack between the two back wall closets. The room is symmetrical. Having measured all possible sub placement positions, I've found midpoint side wall to have the smoothest frequency response by far.
My goals for this build was performance and extension, while keeping it simple. Budget was $1000-2000. I did my research, plugged several sets of numbers into Winisd and decided on using the Dayton Audio HF15 driver in a sealed dual opposed cab, four drivers and two cabs. While I've designed and built hundreds of car audio sub cabs professionally and as a amateur home audio DIYer back in the eighties and nineties (sealed, ported, band pass, isobaric, dual opposed, etc), I haven't built any subs for over fifteen years. My first opposed driver sub build was in 1987 with 4-10" subs in a dual dual-opposed config. Very clean and tight sound. In recent years the dual opposed design has become quite popular. Enter the Sublimator Duo. Every good sub needs a name. I came up with word Sublimator years ago. It's based on the the words "sublimation" and "sublime" which both have all the appropriate meanings and innuendos which could be used to describe a subwoofers qualities and actions. Sublimator Duo is in reference to dual drivers of these subs. There's also a Sublimator Quad on the drawing board for a future date. My goals and expectations were to get 115db@20hz and 100db@10hz. I don't have the OM graphs for the DefTech(sold the sub), but the sub was flat to about 20hz. The turn is more like a cliff with no real useable output below 20hz, and when I say below 20hz, I mean 19hz. So I did my research, which was primarily reading the extensive resources provided here by the "DIY Pros", for which I'm very grateful, then plugged several sets of numbers into Winisd and decided on using the Dayton Audio HF15 driver in a sealed dual opposed cab, four drivers and two cabs. While this driver is one of the more popular units out there, my reason for picking this driver was for its low distortion capabilities and proven sound quality. Xmax and spl wasn't my first concern obviously or I would have gone elsewhere. It took two weeks to build the cabs from start to finish or to the state they are now. Once completed, I powered them with a new Behringer EP4000 (currently temporarily standing in the corner due to noisy fan and no remote trigger), and currently, with some older amps I've pulled from storage, two Parasound HCA1500a bridged providing 630 watts into a 8ohm load. Shortly after startup I had two drivers make noise and had them replaced, which took several weeks to turn around.
￼I've have now been enjoying the subs for a month and they sound fantastic. Quite a different sound from the Supercube. Acoustic bass, cello and kettle drums have a realism, texture and correctness that I haven't experienced before. The dynamics are exceptional. Ferocious when they need be, but soft and subtle when thats called. The sound is extremely clean and highly resolved, with huge dynamics. Having the fat ULF heft impresses me as much during low levels as it does at bombastic, bass heavy, levels. I used to constantly fiddle with my other subs, as I was never really satisfied with the sound. The smooth, extended, low distortion sound I have now, has been a real joy to listen too. Watching movies is likewise a new experience. In the past anything above -13db just lost dynamics with the limiter/roll off of the DefTech. What a difference to not be sub limited. Having usable ULF output changes everything. I now revel in the gorgeous, accurate sound, instead of critiquing everything. True to the source in every way.
The last few weeks I've spent OmniMic'ing the subs and making various comparisons and graphs. For instance, with and without Audyssey comparing frequency response at various listening positions, different crossover points, room gain, etc. Now that the subs have a few hours on them, I'll measure a few movies. As I only had my iPhone to snap pics during the build, the pics are pretty disappointing. Oh well, here goes.