|Arts and Communication Faire, April 20, 2001|
|Dr. Higgins' students presented some of their loudspeaker design and construction projects at the art faire. Unfortunately, we had to use the gymnasium, so the acoustics weren't optimal. Below are some pictures of the event and projects:|
|Rehearsing lines before show starts. The students wrote a script to help the audience (other high school students) to understand the principles used in the design and construction of their loudspeakers.|
|Student body president introducing the event.|
|Julie walks around the gym showing Ashley's very attractively constructed crossover network (high gloss black mdf box with 5/16 inch plexiglass cover to hold tweeter, woofer and amplifier connectors and allowing full visual inspection without opening box).|
|Assembly of assorted loudspeaker designs. Top row: #1 2-way (Dayton 1 inch titanium, 5 inch Bravox, vented); #2,3 2-way (Dayton 1/2 inch mylar tweeter, 5 inch Bravox, vented); #4 2-way (Dayton 1 inch titanium, 6.5 inch Goldwood DVC, sealed); Middle row: #1,2 Pioneer full-range 8 inch, sealed); #3,4 same as top row #1; #5,6 2-way (piezo horn and 8 inch Bravox, sealed with Scanspeak resistive vent); #7,8 3-way (piezo horn, pioneer sealed midrange, and 8 inch Bravox, vented box); Bottom row: #1 2-way (piezo horn and 8 inch Bravox, vented); #2 2-way (smaller Motorola piezo horn and 8 inch Bravox, sealed); #3 2-way (Dayton 1 1/8 inch soft dome and 8 inch Bravox, truncated pyramid, sealed with Scanspeak resistive vent on bottom, supporting legs not yet installed; matching speaker is shown below with a grill plate)|
|Farm's line array (she's the one standing in center photo). Each line array has 20 drivers, PE #269-469, arranged electrically and acoustically in groups of 5 (there are 5 parallel connections and a separate internal chamber for each group of five drivers). Each group is wired in series generating a nominal 6.33 ohm load. The cabinet is constructed of 3/4 inch oak plywood and is trapezoidal to minimize internal standing waves. Pipe resonances are further eliminated by breaking the line into 4 separate chambers. 10 internal braces made from 5/8 inch mdf (4 with air flow cutouts) serve from top to bottom to provide strength and reduce cabinet vibrations. As can be seen in the right side photo, each compartment is vented (rectangular 4x6 inch 1.75 inch in length). All joints are tongue and groove (hours of routing!). The internal surfaces (except baffle) are lined with 1/2 inch thick carpet underlay, heavy fiber with random foam dispersal. We'll be posting this project soon on another page complete with detailed construction and Clio testing data. Future pics will show stained wood, too.|
|Ashley's wonderful bookshelf speakers. These are based on the Dayton #295-310, 8 inch midbass driver and the #275-070 silk-dome tweeter. She's using a Scanspeak resistive vent and a highly modified 3rd order Butterworth crossover network mounted in separate enclosures (with a clear plexiglass cover). We have talked about these speakers before on the PE tech board. We'll be preparing a separate page for outlining details of construction and testing data soon, as well.|
|Quentin's speaker (on the left below) has already been discussed at:
|The speaker on the right is Daniel's. It is identical to Quentin's except for the Motorola piezo horn tweeter and the associated changes in the crossover network. In blind tests they sound remarkably alike. One can quickly identify them by moving verically past the horn lens's angle, though.|
|Fong's 12 inch Pioneer subwoofer (for auto, left photo) in a large sealed box.
This crosses over to a sealed cup midrange and some Legacy tweeters (not shown). To the right is Phuc's full-range Pioneer 4.5 inch vented speaker. Along side is our "infamous" cornbread speaker #269-469) containing the same driver as Farm's line array. A Scanspeak resistive vent is attached to the bottom.
|Lindsey's truncated cylinder as discussed above is on the far left. Notice the external crossover box to it's left. Ashwin's MTM speaker is near left. He chose Goldwood 6.5 inch DVC drivers and the Dayton shielded 1" titanium dome tweeter and used a sealed box..|
|Ashley, Julie, and Kim all built center-channel speakers using the Goldwood shielded 6.5 inch DVC drivers and Dayton 1 1/8 soft dome tweeters. The tweeters are not shielded, so center channel use will depend on particular TV sensitivity and actual placement. Notice that all crossovers are mounted in external boxes to keep speaker box size down and to allow tweaking without prying open well-sealed boxes. The boxes use Scanspeak resistive vents.|
|Our home-made 40 speaker control switch box. When completed it will also activate a small light on each speaker as it plays. In back of photo lower right.|