Performance Optimized Down Fire Sealed 11" Enclosure | Stereo Integrity BM-11

No. The baffle is cut direct fit at 254 mm for the Stereo Integrity BM-11 and the airspace is built to that driver's published requirement. The BM-11 is an unusual size, a shallow mount 11 inch on a 283 mm frame, and very little else shares its footprint.

Even where another driver dropped into the hole, it would be loading into an airspace engineered around a Qts of roughly 0.8, and the alignment printed on this page would no longer describe what you own.

Because the driver is. A sealed box can only ever raise total Q above the driver's own Qts, never lower it, and the BM-11's Qts sits near 0.8 across every published parameter set. That puts the floor for any sealed box, of any size, above the textbook 0.707 target.

This is not a fault in the cabinet or in the driver. The BM-11 is designed as a small sealed box driver with a heavy cone and a compliant suspension, and Stereo Integrity recommends 0.30 to 0.75 cubic feet for it. At the 0.40 this cabinet delivers, system Qtc lands between 1.26 and 1.43 depending on whose parameters you use.

The BM-11 is rated 500 watts RMS, so target 500 watts RMS at the final impedance. The voice coil is dual 2 ohm, giving 4 ohms wired in series or 1 ohm in parallel.

The 1 ohm parallel load is the one to be careful with. Many amplifiers are not stable at 1 ohm and running one there is how amplifiers die. Series for 4 ohms is the safe answer unless your amplifier is explicitly rated 1 ohm stable.

The cabinet is 5.00 inches tall measured in the down fire position, and that figure excludes the standoffs. The standoffs hold 1.75 inches under the baffle, so plan your space around a finished stack of roughly <strong>6.75 inches</strong>.

The footprint is 22.84 inches wide by 15.00 deep. That is narrower than the 30 inch platform most Performance Optimized down fire cabinets share, because the width was solved to hit 0.40 cubic feet exactly rather than rounded to a stock size.

The baffle is two bonded 3/4 inch sheets, 1.5 inches through. A subwoofer pushes as hard against its mounting surface as it does against the air, and a single 3/4 inch panel flexes under that load, which smears output and works the driver loose over time.

The outer layer is machined as a flush recess so the driver bolts to the inner layer, which recovers 3/4 inch of internal clearance. The inserts also get real material to hold in, so the driver bolts down to metal rather than into MDF.

Anechoic F3 lands between 41.1 and 42.6 Hz across the three published parameter sets. Note that on a high Q alignment like this one the F3 sits below the system resonance rather than above it, and there is a lift at resonance rather than a flat shelf running into it.

Those figures are anechoic and exclude cabin gain. In a car the transfer function of the cabin adds real output below 50 Hz, so in-vehicle response runs deeper than the number 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 on this driver would push the alignment further from Stereo Integrity's stated target rather than closer to it.

No. This is an enclosure only. You receive the cabinet finished in plush black carpet, with threaded inserts at the driver position, stainless machine screws, one side-mounted pre-wired terminal cup, the standoffs and the polyfill lining already in place.

The BM-11 is purchased separately. The cabinet is cut direct fit to that driver, so it is not a general purpose 11 inch box.