Dayton Audio Ultimax II UMII8 Box: Ported 8" Professional Series Enclosure Single 8" Ported enclosure

The slot is gated at 480 W: the channel runs 19.6 m/s and the mouth 10.9, and the cone peaks at 12.1 of its 18 mm with the subsonic filter in place. Passband ripple is 1.7 dB. Tuning is chosen for in-car response rather than an anechoic curve: a vehicle adds roughly 12 dB per octave below about 45 Hz, and this tuning is where that sum comes out flattest across 25 to 60 Hz.

The Ultimax II UMII8 also builds in the Performance Optimized ported down-fire, the smaller and cheaper box. The Professional cabinet is the step up for it: a 2.25 inch three-layer baffle with the woofer flush in the outer layer, and a slot port gated at 480 W. It carries a 2 year warranty, against 1 year on the Performance Optimized lines.

Threaded inserts pressed into the baffle on the published 7.874 inch bolt circle, stainless machine screws included. The inserts are in the baffle when it arrives; the machine screws are in the terminal cup bag.

Yes, at 27 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 Dayton Audio Ultimax II UMII8 at 67 percent of its usable travel at 480 W.

Not one we can show you. We do not build a sealed enclosure for the Dayton Audio Ultimax II UMII8 and Dayton Audio publish no sealed volume for it, so the Performance Graphs tab carries no ported-versus-sealed chart: the only sealed box left to plot would be this cabinet stuffed and sealed, which nobody would build, and a comparison against it would tell you nothing you could buy. What a vented box gives up is the region below tuning, where the cone unloads and the 27 Hz subsonic filter takes over; around 34.0 Hz the vent carries the load and cone travel drops to its minimum, which no sealed alignment can do.

It is a vertical slot beside the woofer, the full height of the cavity, 1.50 inches wide and 18.8 square inches. It runs 6.25 inches to the back wall and turns once along it for 18.50 inches; the fold costs about 1.5 Hz and the port is cut for it. The channel runs at 19.6 metres per second at 480 W, 53 percent of its turbulence limit, and the mouth edges carry a 1/2 inch roundover so the air leaves the face at 10.9 metres per second against the 17 metres per second threshold where a slot starts to chuff.

48 lb, 30.00" W x 14.00" H x 11.50" D external. Every Professional cabinet is priced the same way, by its size: this one is 2.80 cubic feet outside. Delivery to the 48 states is inside the price; it ships as a 48 lb parcel and checkout adds nothing. Do not add polyfill; it ships dry on purpose.

No. This is an enclosure only, cut for the Dayton Audio Ultimax II UMII8 specifically: the 7.311 inch cutout, the 5.669 inch mounting depth allowance and the 1.16 cubic foot alignment all come from Dayton Audio's published parameters. Dayton make the UMII8 in one version, dual 2 ohm (UMII8-22). Bring your own driver.