Performance Optimized Down Fire Sealed 12" Enclosure | Hertz Mille Pro MPS 300 Single 12" Sealed enclosure

On this size the S4 is the better damped driver, with a free-air Qts of 0.42 against the S2's 0.51. In this cabinet the S4 lands at Qtc 0.812 and the S2 at 1.003. The S2 does reach deeper, F3 37.1 Hz against the S4's 39.5.

Important: this is the opposite of the 10 inch MPS 250, where the S2 is the tighter driver. Same series, reversed pattern between sizes. Both models are single voice coil, so impedance is fixed by the model - 2 ohms for the S2, 4 ohms for the S4. Check your amplifier first, then choose the S4 for control or the S2 for extension.

The 12 reaches substantially deeper for 1.4375 inches of additional cabinet height. This enclosure stands 6.375 inches against the 10 inch model's 4.9375, and its S2 variant reaches an F3 of 37.1 Hz against the 10's 48.4 Hz. That difference comes from the drivers: the MPS 300 has a 24 Hz free-air resonance and 64.9 liters of Vas, against 28 Hz and 24.5 liters on the MPS 250.

Both share the 30 by 15 inch footprint, the same 500 watt RMS rating and the same 16.8mm Xmax. Mounting depth is nearly identical at 3.46 inches versus 3.25. If your vertical clearance allows the 12, it is the clear choice. The 10 exists for installs where it does not.

Yes, and that is worth stating because it is not universal. Running Hertz's own published Qts and Vas through standard sealed box math at their recommended volume produces a corner frequency within 0.2 Hz of the figure printed in their manual on both variants. Their enclosure data and their Thiele-Small data agree with each other.

Several other manufacturers in this category publish enclosure tables that do not reconcile with their own driver parameters, which forces us to publish computed figures instead. Hertz did not have that problem.

16.8mm one-way, the same as the 10 inch model and exceptional for a shallow-mount driver. Combined with 500 watts RMS, a 3.46 inch mounting depth and a 24 Hz free-air resonance, the MPS 300 delivers real low frequency capability from a package thin enough for a down fire cabinet just over 6 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 fully 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.

Down Fire cabinets are built with square corners as a series standard. The 3 inch top down corner radius used on other Proline X alignments does not apply here. A down fire box is a low, wide platform that sits flat against a floor or under a seat, and square corners maximize usable internal volume for a given footprint while keeping the cabinet stable on its mounting surface.

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 is what keeps the cabinet airtight under sustained pressure cycling. The front baffle is a double layer at 1.5 inches, two bonded 3/4 inch sheets, which carries real structural load with an 11 inch cutout in a cabinet this shallow. Perimeter cross-bracing and pre-installed polyfill complete the build. Assembled and inspected in Tullahoma, Tennessee.

No. This listing is for the enclosure only. Bring your own Hertz Mille Pro MPS 300 S2 or MPS 300 S4. The cutout and mounting depth are direct fit for either version.