Alpine's SBS-1041BP bandpass enclosure uses ported and sealed chambers to achieve its wall-of-sound bass.

Alpine Type-S SBS-1041BP 10" bandpass enclosure
Alpine's SBS-1041BP features their Type-S 10" woofer in a bandpass enclosure, a hybrid design which combines sealed and ported chambers. It works like this — the subwoofer is mounted in a sealed enclosure, firing outward into a ported enclosure and through the ports into your vehicle. The design is extraordinarily efficient, so you get maximum output from the speaker within a limited frequency range. The down side — to operate properly, a bandpass enclosure must be built to exact tolerances and its ports must be precisely trimmed to complement the output of its woofer. Any errors in construction or tuning result in loss of accuracy.

At one time, the bandpass box was the ugly duckling of the subwoofer world, used by budget builders to get maximum output from cheap subwoofers. With modern manufacturing techniques, the design has come into its own — especially for preloaded enclosures, where the manufacturer can ensure a perfect match of sub to enclosure. Alpine's SBS-1041BP is the largest of the 4 enclosures tested, and it's no coincidence that it has the biggest sound.

I played a Buddy Guy cut through the Kicker sealed box as a reference, then hooked up the Alpine bandpass unit. To give you an idea of the difference in efficiency, I had to fade 6 steps forward toward the front speakers (no subwoofer level control on my Pioneer receiver) to lower the Alpine's level to that of the sealed box. And efficiency wasn't the only difference — the Alpine delivered the low frequencies with an undeniable authority that was missing before. The kick drum was hitting with a physical force that I could feel, and the low string on the 5-string electric bass was shaking my mirrors. And all this was happening after I'd turned it down! So all these things are good, right? Then why would anybody ever buy a sealed box?

Accuracy is why. The SBS-1041BP sounded awesome on the Buddy Guy cut, and totally fantastic on the reggae cuts I played. But the acoustic bass on the Hank Williams III tune sounded mushy, and I noticed a distinct lack of electric bass definition in some of the more complex mixes. There's a little bit of overhang, a subtle resonance that you hear on occasion — it's not a big problem, but you don't get the same "stop-on-a-dime" sound that the sealed box delivers. The bass is so heavy that it tends to overwhelm the subtleties in your music.

The specialist
Now I am absolutely not dissing the Alpine when I point this out. Think of the sealed box as the jack of all trades, the master of none — it will sound good (but rarely awe-inspiring) on everything you play. Conversely, the bandpass enclosure is a specialist. It won't sound good on everything, but it will sound unbelievably great on some types of music. The Redd Kross Show World CD, for instance, can sound a little brash in my car at times, but the Alpine's powerful delivery balanced out the aggressively mixed mids and highs to make that disc sound better than I've ever heard it before.

Conclusion: "Thick" is the first word that comes to mind to describe the SBS-1041BP. The bass is not really punchy, it's more like a big, swampy wall of low end that powers the music — very cool on some tunes, overwhelming on others. If you listen to harder stuff (metal, hard rock, industrial) or music with strong bass content (reggae, hip hop) and you like to hear your bass LOUD, the bandpass box is a great way to go. And, if your amp doesn't have quite as much power as you'd like, you'll get the most bang for your buck from this specialized design.