Performance Optimized Wedge Ported 12" Enclosure Sundown Audio Horizon HZ 12 · Single 12" Ported enclosure

A 0.516 Qts on 54.36 litres of Vas wants air, and 33 Hz brings the ripple to 1.23 dB, inside the 4.5 dB cap. Sundown does not publish a sealed box for the Horizon HZ 12 to compare this curve against. At the driver's rated 500 watts the channel runs at 18.5 metres per second and the mouth at 11.5, under the 17 where a slot port starts to chuff. The base depth of 14.39 inches is set by the port panel clearing the motor at 8.50 inches, not by the 7.64 inch magnet top, and it stays comfortably under the 18 inch base depth cap. Tuning is chosen for in-car response rather than an anechoic curve: a vehicle adds roughly 12 dB per octave below about 45 Hz. In this cabinet that lands at 1.2 dB of in-car spread across 25 to 60 Hz.

The raked face is the seat side. A factory rear seat back leans about 20 degrees off vertical, so the cabinet sits flat against it and uses floor a square box wastes. The baffle stays vertical and fires rearward into the trunk, which acts as the acoustic extension into the cabin. This one is 14.39 inches deep at the base and 8.75 at the top, 30.00 wide and 16 tall.

Yes, at 26 Hz, 24 dB per octave. Below tuning a vented box stops loading the cone and excursion runs away toward DC. With the filter in place this cabinet puts the Sundown Audio Horizon HZ 12 at 53 percent of its usable travel at full rated power; without it there is no meaningful number to quote.

Sundown Audio rate the Horizon HZ 12 at 500 W RMS and that is the thermal ceiling. The Performance Graphs tab shows the mechanical limit, the power at which the cone reaches the end of its travel in this cabinet: here the cone sits at 53 percent of usable travel at the rating, so heat is what stops you, not travel. A D2 coil is 4 ohms in series or 1 ohm in parallel; run series unless the amplifier is rated for 1 ohm. A D4 is 8 series or 2 parallel.

The two alignments converge at the bottom of the band on this driver rather than crossing cleanly, so there is no meaningful subsonic advantage either way. Above 25 Hz the vent is the louder of the two. The Performance Graphs tab plots this cabinet against Sundown Audio's recommended sealed box, 1.00 cu ft.

It is a triangular slot in the bottom-rear corner: the floor and the raked back wall are two sides, one bevelled panel is the third. It runs across the cabinet, opens into the box through a 3.73 inch gap at the far end and exits through the side panel as the same triangle. Straight, no bend: 24.52 inches of path and 18.4 square inches of channel running at 18.5 metres per second, 53 percent of its turbulence limit. The three mouth edges are rounded over at 1/2 inch, so the opening at the face is 29.5 square inches and the air leaves it at 11.5 metres per second against the 17.0 threshold where a slot port starts to chuff; the panel's throat end is rounded at 3/8 inch for the same reason. The terminal cup is on the other side.

No, and do not add any. Every sealed Proline X enclosure ships with polyfill; a ported one must not, because damping changes the effective volume the port is tuned against. The port here is cut to 24.52 inches for 33.0 Hz. Stuff it and you move the tuning without shortening the port.

No. This is an enclosure only, cut for the Sundown Audio Horizon HZ 12 specifically: the 11.200 inch cutout, the 6.300 inch mounting depth allowance and the 1.44 cubic foot alignment all come from Sundown Audio's published parameters. It fits both coil versions; the alignment published here is the D4. Bring your own driver.