Performance Optimized Down Fire Wide Sealed Dual 12" Enclosure Hertz Mille Pro MPS 300 · Dual 12" Sealed enclosure

Because some installs run out of height or depth before they run out of length. The standard Hertz Mille Pro MPS 300 Down Fire cabinet is 30 by 15 by 10.75 inches; this one is 41 by 14 by 8.375. Spreading the airspace along 11 more inches lets the cabinet stand 2.375 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 10.75 inches and holds 0.856 cubic feet net per chamber; this one is 41 by 14 by 8.375 inches and holds 0.804 cubic feet net per chamber.

The airspaces are within 0.052 cubic feet per chamber, so the alignment is close: Qtc 1.001 against 0.978 on the S2, 0.811 against 0.793 on the S4. 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.

On this size the S4 is the better damped driver, with a free-air Qts of 0.42 against the S2's 0.51, landing at Qtc 0.811 per chamber versus 1.001. The S2 reaches deeper, F3 37.0 Hz against 39.4.

This is the opposite of the 10 inch MPS 250, where the S2 is the tighter driver. Whichever you choose, use two of the same model; mismatched drivers between chambers will not track each other.

One side-mounted Proline X terminal cup with a single pair of posts, pre-wired in 12 gauge OFC to both driver positions in parallel. You do not wire the two chambers separately at the amplifier.

Both MPS 300 models are single voice coil, so the load is set by the model: a pair of S2 drivers in parallel presents 1 ohm, a pair of S4 drivers 2 ohms. Confirm that against your amplifier's minimum stable load before powering the system.

Two drivers sharing one sealed volume load each other: each driver's compression stroke becomes the pressure the other works against, which blurs the alignment either would have alone. A bonded full-height 3/4 inch divider gives each MPS 300 its own 0.804 cubic feet and its own polyfill.

It also means the alignment on this page is the alignment in each chamber, not an average across a shared box, and the divider ties the walls together across the 41 inch span.

Side mounted, and one cup serves both chambers. Every Proline X Performance Optimized enclosure uses a side mounted terminal cup regardless of alignment. On this cabinet that keeps the connection accessible with the enclosure installed, since both baffles face 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, which keeps both chambers airtight under sustained pressure cycling. The chamber divider is a full-height bonded 3/4 inch panel. Corners are square, the Down Fire series standard.

Front baffles are double layer at 1.5 inches at both positions, outer layer machined as a flush recess, with two sets of 8/32 threaded inserts and stainless machine screws. Polyfill is installed as a light wall lining in each chamber. Assembled and inspected in Tullahoma, Tennessee.

No. This listing is for the enclosure only. Bring your own pair of Hertz Mille Pro MPS 300 S2 or MPS 300 S4. The cutouts and mounting depth are direct fit at both positions; use two of the same model.