AudioControl Spike SPK-8 Box: Sealed 8" Wedge Enclosure Single 8" Sealed enclosure

The Spike SPK-8, yes, in the SPK-8S4 (single 4 ohm) version. The baffle is cut to 7.250 in for AudioControl's 8.425 in frame. The 4.29 inch motor clears the cabinet with 0.75 inch to spare. This cabinet is listed for the SPK-8S4 (single 4 ohm) only. AudioControl's SPK-8S2 (single 2 ohm) version reads Qtc 0.56 in the same airspace, too damped to sound right sealed, so it is not offered in this enclosure.

Any other 8, no. The airspace is engineered around the Spike SPK-8's own Qts and Vas, and a different woofer that happened to drop into the hole would not see the alignment printed on this page.

0.50 cubic feet net on AudioControl's published figures: the SPK-8S4 (single 4 ohm) reads Qtc 0.852 with resonance at 68.2 Hz and half power at 58.6 Hz. That is AudioControl's own recommended sealed size for this driver, 0.5 cubic feet, between their 0.25 minimum and 0.75 maximum. That is well above maximally flat: a clear lift near resonance and extra midbass, the way AudioControl voices it in this size.

Cabinet gain in a vehicle lifts the bottom end further, so in the car this reads deeper than the anechoic figures.

AudioControl rates the Spike SPK-8 at 350 watts RMS, so target 244 to 350 watts RMS at the final load.

This cabinet is for the Spike SPK-8 SPK-8S4 (single 4 ohm): the SPK-8S4 (single 4 ohm) is a single 4 ohm coil, a 4 ohm load. A parallel load at or under 1 ohm needs an amplifier rated for it. Confirm your amplifier's minimum stable impedance first.

The seat-side face carries a 20 degree rake that matches the lean of a factory rear seat back, so the cabinet sits flush against it and the cargo space in front stays usable. The baffle is the vertical trunk-lid-side face, so the driver fires rearward into the trunk cavity.

The trunk acts as an acoustic extension for the sealed box, and the cabin adds real output below 50 Hz, so in-vehicle response runs deeper than the anechoic 58.6 Hz on this page.

The baffle is two bonded 3/4 inch sheets, 1.5 inches through. A single 3/4 inch panel flexes under the pressure an 8 inch woofer puts on it at 350 watts, which smears output and works the driver loose over time; the second layer stiffens the face and gives the mounting hardware twice the material to bite.

The outer layer is machined as a flush recess to AudioControl's 8.425 inch frame, so the driver bolts to the inner layer and sits flush with the gloss black acrylic insert.

Anechoic F3 is 58.6 Hz. Above Qtc 0.707 F3 sits below fc, so the response carries a small lift near resonance before it rolls off.

Those figures exclude cabin gain. In a car the cabin's transfer function adds real output below 50 Hz, so in-vehicle response runs deeper than the numbers above.

No. Polyfill is already installed as a light wall lining to control internal reflections, and the quantity is chosen so it does not change the acoustic volume.

Do not add more. Packing a sealed box with fill makes it behave as though it were larger, which walks the alignment away from the 0.50 cubic feet this cabinet was built to.

No driver. This is an enclosure only. You receive the cabinet finished in plush black carpet with the gloss black acrylic baffle insert, one side-mounted pre-wired terminal cup, the polyfill lining already in place, and a threaded insert kit with stainless machine screws.

The inserts are not pre-installed: AudioControl publishes no bolt circle for the SPK-8, so set the driver in its recess, mark its holes, drill and press the inserts. The AudioControl Spike SPK-8 is purchased separately, and the cabinet is cut direct fit to it, not a general purpose 8 inch box.