doucanoe said:
Zilch, would a higher tuning help out with the D130 in your opinion? Not much higher, but higher none the less.
I'm not sure about the cabinet internal depth. The internal volume from the dimensions Redboy gave on the photo is somewhat larger than 4.5 cuft. I used 4.5 as the
net internal volume. The driver mounted on the rear of the baffle consumes ~0.3 cuft.
Adding more bracing will presumably be traded off with more comprehensive fiberglass damping inside, which adds virtual volume. It's a wash.
As you suggest, BB6P recommends a slightly higher tuning, 44 Hz, for extended bass alignment of D130 in that size box. BB6P iterates to the maximally flat response. But tuning to 40 Hz you originally suggested gives a little more bass, and since Redboy's bass shy with this combination, I think it's a worthy tradeoff.
BB6P and other box modeling programs all give slightly different results, since they each use different algorithms for performing the calculations. The science is not exact, but most who build to BB6P prescriptions report good results. I always end up shortening the ducts a bit after measuring the actual tuned frequency of the finished box.
Both tunings are shown in this attachment. For the higher one (red,) the duct length is only 1", which is why I earlier suggested that his box with just the hole (no duct) was closer to the optimal tuning for D130.
You can see there, with the lower tuning, the usable bass is 0.58 Hz lower. The higher tuning has a bit better power handling, but Redboy said he's not particularly interested in cranking these, so I opted for slightly more low bass.
From the looks of it, Redboy's original tuning is dreadfully low; they won't handle hardly any power at all in that alignment due to D130's limited Xmax (cone excursion), as Jblmar cautioned in Post #19 here. If we knew the actual duct length, I could plot it for comparison....
