Performance Optimized Down Fire Wide Sealed 12" Enclosure Diamond Audio DMD-SH · Single 12" Sealed enclosure

Because some installs run out of height or depth before they run out of length. The standard Diamond Audio DMD-SH 12 Down Fire cabinet is 30 by 15 by 8.3125 inches; this one is 41 by 14 by 7.0625. Spreading the airspace along 11 more inches lets the cabinet stand 1.25 inches lower, and at 14 inches deep it is 1 inch shallower front to back, about the minimum a 12 inch frame needs.

If you have 41 inches of run and height or depth is the limit, this is the shape. If length is the limit, the standard 30 x 15 is the better fit.

Same driver, same construction, different shape. The standard box is 30 by 15 by 8.3125 inches and holds 1.213 cubic feet net; this one is 41 by 14 by 7.0625 inches and holds 1.252 cubic feet net. The standard box is listed at 1.25, but our solver puts its true net at 1.213.

The airspace is matched, so the alignment is effectively the same. The choice is about the shape of your space: the standard box when length is limited, this one when height or depth is the limit and you have 41 inches of run.

For a sealed enclosure the DMD122SH is the better damped choice. Its free-air Qts is 0.77 against 0.91, and since system Qtc can never fall below the driver's Qts, the D4 is underdamped in any sealed box. In this cabinet the D2 lands at Qtc 1.052 with F3 at 48.4 Hz, and the D4 at Qtc 1.246 with F3 at 46.4 Hz.

The D4 carries more motor force, 16.4 T against 13.7, and more excursion, 8.8mm against 7.9mm, and its extra lift puts F3 about 2 Hz lower. Check your amplifier's stable impedance first; if either works, take the D2 for control or the D4 for a fuller corner.

Because Diamond's enclosure table does not reconcile with the Thiele-Small parameters printed on the same page. Running their own published Qts and Vas through standard sealed box math at their suggested volume gives a noticeably higher Qtc than their table prints, and every variant is off in the same direction.

That gap is too large to be a gross versus net convention issue. We publish figures computed directly from the driver parameters, because those are what the driver will do in this enclosure.

Because the alignment is better. Diamond suggests 0.75 gross; at 1.252 cubic feet net both coils are better damped and reach a little lower than they would in the smaller box. Diamond's own manual presents its enclosure table as a suggestion rather than a specification. On the wide footprint the extra air costs very little height: this cabinet is 7.0625 inches tall.

Side mounted. Every Proline X Performance Optimized enclosure uses a side mounted terminal cup regardless of alignment, whether standard, wedge, or down fire. On this cabinet that keeps the connection accessible with the enclosure in its installed position, since the baffle faces the floor. The cup is our Proline X ABS and carbon fiber composite unit, recessed, with stainless hardware, copper ring terminals, and pre-wired 12 gauge OFC.

V-groove and dado joinery, CNC cut on ShopSabre routers from Langboard Elite MDF. Every panel joint is a machined interlocking groove that mechanically locks the panels before adhesive is applied, which keeps the cabinet airtight under sustained pressure cycling. Corners are square, the Down Fire series standard.

The front baffle is a double layer at 1.5 inches, two bonded 3/4 inch sheets, with the outer layer machined as a flush recess so the driver bolts to the inner layer. A windowed U-brace ties the long 41 inch panels together and polyfill is installed as a light wall lining. The double baffle carries real structural load around an 11.06 inch cutout. Assembled and inspected in Tullahoma, Tennessee.

No. This listing is for the enclosure only. Bring your own Diamond Audio DMD122SH or DMD124SH. The cutout and mounting depth are direct fit for either version.