Please send questions to:Car Audio and Electronics, c/o Tech Panel774 S. Placentia Ave., Placentia, CA 92870e-mail: techpanel@mcmullenargus.com
Hi Derek.Q First of all, thank you for this column. I love the no-BS approach in this magazine. I am a new reader, so I have an embarrassing question. I have an early BMW 2002. For my sub I'm using the old Coustic Bass Pump, which has been upgraded somewhat with newer 8" drivers. If you are not familiar with this enclosure, basically it is a steel housing that mounts two bass drivers firing toward one another into a common plenum, which is ported to the interior of the car. The reasons I got one ten years ago, and the reasons I still like it are: 1) It is minimally invasive to the car, as it requires only one 4" hole for the port and four mounting screw holes. 2) It mounts up out of the way in the trunk under the package shelf, using very little trunk space. 3) It is stealth, in that only a generic looking 4" grille shows from the top. 4) It is relatively lightweight compared to MDF boxes or tubes.
Of course now, I'm looking for more bass. My favorite type of music ranges from Catherine Wheel to Latin jazz to rockabilly and some hip-hop. I recently bought a larger sub amp which is spec'd to run 600 watts into 4 ohms, 1200 watts into 2 ohms, or 1800 watts into 1 ohm, mono, and I'm now looking for much better drivers. My problem is I'd really like to stay with the above type of enclosure. That is, unless there are no high performance drivers being made which would work, or if the consensus among those in the know is this is a hopeless enclosure design. I guess this would probably be considered a free air application, but everyone today seems to be building drivers, which use a sealed box for damping. The choices in subs go up dramatically in 10" or 12" sizes, versus 8", so I would gladly build a new similar enclosure, which would take a larger driver, having access to any and all the tools. I really am not concerned with price, as I expect to pay more to make this unusual thing work better. If a driver is built primarily to work in a sealed box, will ample wattage make up for an enclosure, which is not sealed? Could I simply restrict the port size to gain dampening? What do you recommend I do?
Name and address withheld by request.
It's good to hear that your reasons for originally buying the Bass Pump were not for producing massive amounts of bass. You made a good decision in that you chose the product based on your need rather than buying a product because it's really cool, and then trying to force it to work in the wrong application. There are no hopeless designs, just designs forced to do what they're not designed to do. It's also great to hear that you have enjoyed ten years of service from your subwoofer when the typical lifespan of a subwoofer is probably less than five years.
Now is your chance to move on. I am also a fan of the "discrete install", but it is important to recognize when a product is no longer appropriate. When the Bass Pump appeared on the market, it solved a major problem of delivering bass from a decent-sized subwoofer through a slim rear deck. Trying to drive 10" or 12" subs on abundant power through the plenum will give you the worst sounding bagpipes you've ever heard!
New installation techniques include fabricating stealth grills and lightweight fiberglass cabinets to provide superior bass in an inconspicuous fashion without major cutting. The trunk of a 2002 is capable of handling almost any cabinet that a beefy sub would require. It's time to retire the Bass Pump and try out the new stealth methods with today's high performance drivers.