Performance Optimized Down Fire Wide Sealed 12" Enclosure Hertz Mille Pro MP 300 · Single 12" Sealed enclosure

Because some installs run out of height or depth before they run out of length. The standard Hertz Mille Pro MP 300 Down Fire cabinet is 30 by 15 by 8.125 inches; this one is 41 by 14 by 8. Spreading the airspace along 11 more inches lets the cabinet stand 0.125 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 8.125 inches and holds 1.126 cubic feet net; this one is 41 by 14 by 8 inches and holds 1.465 cubic feet net.

The wide box holds more because the 6.457 inch motor sets its height, and on a longer footprint that height encloses more air. More air lowers Qtc, a softer, better damped corner. Choose the standard box when length is limited or you want the livelier alignment, this one when height or depth is the limit.

Because the driver's mounting depth sets the minimum cabinet height. The MP 300 mounts 6.457 inches deep, we leave 0.75 inch above the motor, and the cabinet cannot go under 8 inches. On a 41 by 14 footprint that height holds 1.465 cubic feet net, about 41 liters.

The extra volume lowers Qtc, which is the safe direction: the D4.3 lands at Qtc 0.701 with F3 at 40.4 Hz and the D2.3 at Qtc 0.848 with F3 at 35.0 Hz.

They are not the same driver on paper. Hertz publishes Fs 24 Hz, Qts 0.42 and 74 liters for the D4.3, and Fs 23 Hz, Qts 0.48 and 88 liters for the D2.3. In this cabinet the D4.3 is the controlled one, just under maximally flat, and the D2.3 has more lift near the corner and about 5.4 Hz more extension.

Choose the D4.3 for accuracy or the D2.3 for depth and weight, then confirm your amplifier is stable at the load you plan to wire.

Because sensitivity sets how much output you get per watt. Most subwoofers in this category sit in the low to mid 80s, and high-excursion shallow drivers often drop to 81 or 82 dB. A 4 dB advantage is roughly two and a half times the acoustic output from the same amplifier power, so you reach your target on a smaller amplifier or with headroom to spare, which reduces thermal stress over long sessions.

The enclosure has one side-mounted Proline X terminal cup pre-wired in 12 gauge OFC. Final impedance is set at the driver: the MP 300 D2.3 has dual 2 ohm coils, 1 ohm parallel or 4 series, and the MP 300 D4.3 has dual 4 ohm coils, 2 ohms parallel or 8 series. Hertz rates the driver at 600 watts RMS. Confirm your amplifier is stable at your chosen load before powering the system.

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. That matters with an 11.30 inch cutout and an 8.63 kg driver. Assembled and inspected in Tullahoma, Tennessee.

No. This listing is for the enclosure only. Bring your own Hertz Mille Pro MP 300 D2.3 or MP 300 D4.3. The cutout and mounting depth are cut specifically for this driver.