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The Homewrecker



Hoffman's Iron Law states that a woofer's efficiency is proportional to the volume of the enclosure it is mounted in and the cube of its low frequency cutoff. In other words, if you want a loudspeaker with very low frequency extension AND high efficiency, you need an enormous enclosure. Or you could build The Homewrecker. This Instructable will show you how to build a loudspeaker that can mount in most standard interior doorways, using the room as the enclosure. The system is easily removable, though quite heavy. The system shown here is not a high-fidelity system, but it is very efficient (i.e. LOUD) and can reproduce very low frequencies. Based on the parameters of the woofer, this system should easily reach below 30Hz (-3dB) without including the natural boost obtained from room reflections. With this boost included, the system should reach 20Hz - the lower limit of human hearing. All of this bass extension comes at a very respectable 96dB with a 2.83V input (4 ohms). It consists of (8) 12" woofers, (8) 5" midranges, (4) 2" x 5" tweeters, a simple crossover and (4) easy to use mounting brackets. The size and number of speakers can be just about anything you want, but this combination utilizes the available space in a doorway quite well.

The Homewrecker

step 1Get Stuff

The following is a list of the components I used for this system, but these exact parts may be difficult to obtain and can be replaced as described below. - 12" woofers …

step 2Lay Out Driver Placement on Plywood

Standard interior door sizes are 30", 32" and 36" wide and 80" tall. My house is old and most doorways are 29" wide by 80" tall. With these dimensions in mind, I c…

step 3Cut Holes

After marking the centers of the woofer and midrange holes, I used a router with a circle cutting attachment to cut the holes. An adequate job can be done, however, by dra…

step 4Brace the Back

This design relies on four brackets to hold the entire baffle against the door trim, so it must be relatively stiff. To do this, 2 x 4 studs run 66.5" lengthwise do…

step 5Apply Weatherstrip

Apply self-adhesive weatherstrip along each side edge and the top edge, which will create an airtight seal between the baffle and the door trim. I have left the bot…

step 6Make Mounting Brackets

These brackets are designed to pull the speaker baffle tight against the doorway trim. The blue end of the bracket shown below slides in between the trim and the en…

step 7Dry Run

At this point it may be a good idea to test fit the baffle in a doorway. It will be easier to make any necessary tweaks before the drivers are mounted. Make sure t…

step 8Mount Drivers

Mount the drivers using the appropriate screws. I used 1.25" drywall screws for the midranges and black 1" pan heads for the woofers and tweeters (available from Pa…

step 9Wiring and Crossover

The crossover, which routes the proper frequencies to the proper drivers, for this project will be very simple. Crossover design is a very complex and intricate mat…

step 10Notes and Disclaimers

Notes: This system is very heavy and will probably require two people to move it. I will probably mount handles on the front to make it easier to handle and crea…

Via Instructables, Published: 2009.07.26


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