This is a continuation of the discussion in this thread. There was some further discussion here as well. My current low end setup, chronicled here, consists of 8x LMS Ultra 5400s in sealed enclosures with 4x FP14000 powering them, pictured below. Kind of absurd to upgrade, but that's what this project is about. I feel the sealed enclosures I built left a lot on the table under 40hz that I can pick up by going with a vented alignment. A full build gallery is available here.
The outer dimensions of the new enclosures measure 48" long, 46" high, and 30" deep. Ports will be oriented on the sides as I will be stacking these. These dimensions were chosen mainly to fit in the current space that I have, stacked two high.
I've got two of these built, and I consider it a great success. It output as modeled, though the tuning ended up around 14.7hz, with an effective port length of about 55". I'm going to pick up some more lumber once the roads here are dry. The output from these down low is just so much greater than the sealed boxes. It would take four of them to equal one of these at 15hz. The bass from the ported boxes also feels like it has more impact. You feel it a great deal more in your chest. To make up for the lack of ULF I decided to get some Crowson transducers for my couch, which also add a great deal of tactile feel. Since this setup is on a slab, the ULF from the subs basically does nothing aside from causing my walls to flex an doors to bounce around. I can listen at lower bass levels now with more feel while having more headroom in reserve. Watching previous demo scenes and listening to various bass heavy music so far have me convinced this was the right move.
Since completing all four of these, I am incredibly happy with the results. EQ'd the same the bass is far more visceral and I have a lot more headroom where I needed it.
Bracing was accomplished with strips of left over ply from the build. Handy since it was almost all cut to size already. The boxes are painted with Duratex. Holes filled with spackle.
Sketchup file: download
Cut list: download
Original setup. The new enclosures will be stacked in the same place as the old.
Here is the project half-way through. Can't wait to finish. I can't describe how imposing these are, they still look kind of like toys in the picture, but those are 8' ceilings.
Modeled at 6200w with 13.5hz 3rd order butterworth highpass. I ended up using a 14hz 4th order filter. Very similar results.
Compared to the sealed subs with 8000w input and 11hz 3rd order filter (I have massive room gain in this area, filter prevents over excursion below 7hz). Both of these signal levels push the subs to almost identical excursion levels.
It weighs about 400lbs with the drivers in it. This was built from maple ply, which was excessive, but the selection was poor when I went out to get the lumber for this. The second was built out of some not-so-good 6 ply soft wood sort of like arauco, but worse. It warped really bad and made my life miserable. Thankfully I have a lot of clamps. I found some nice Baltic Birch for $40/sheet that I'll be using for the last two.
Results, as modeled. Huge gains. It's hard to move these things. This was back-to-back with a sealed enclosure in the same location. No changes otherwise. This measurement was taken with a faulty mic. Apparently I shocked it one too many times or something and it was rolling off way sooner than expected. The gains are the same, but the slope is all wrong.
And in room results. There's a null at 80hz where the mic is placed. What's crazy is I still have headroom.
And full system results with XT32
3 Sweeps to determine compression... I can't measure louder with the umik1.
100db to 126db. Interesting how the walls react
THD @ reference level. Mic is compressing/clipping
THD @ OMGWTF level. I think I might be am definitely reaching the ceiling of the mic's limits. I'm afraid to test louder for fear of damaging something in my house.