|Project by ferstler||posted 10-12-2008 02:15 AM||4143 views||0 times favorited||12 comments|
The left and right channel speakers in this system are Allison IC-20 models. They are among the best of their kind ever made and finding a factory-made center speaker that could work with them was impossible. So, I built one of my own, shown in close up, without a grill screen, in the second photo. If you look through the window in the full-room photo you will see my shop out back where the center speaker was made.
The center speaker uses Allison tweeters and midrange drivers, just like the IC-20s to the left and right, but with only two apiece instead of four like the bigger speakers. The woofer is a single Allison IC-20 unit. The IC-20s have two such woofers each. The crossover network, built from scratch by me, is a hybrid design combining values used in several different Allison models over the years. While the center speaker is only half as powerful as the left/right mains, it is more than powerful enough to do the job in this room.
The cabinet top, bottom, and sides of the center system is made of .75-inch pine, stained and coated with polyurethane. The front and back are mdf, painted black. The tweeters and midrange drivers are located in a sealed sub-enclosure, so there is no need for rubberized gasketing around their mount perimeters to seal the woofer enclosure space. The front panel is angled back 4 degrees to allow the vertical array to focus its somewhat narrow vertical dispersion cone at seated ear height across the room. The left and right IC-20 systems are tall enough to not need front-panel tilting. (The 45-degree side-angled-panel design of the IC-20 units, which each have a vertical row of drivers like the single plane of the center speaker, gives them superb horizontal dispersion, and the center unit, due to the design of the Allison drivers, also has wide dispersion.)
All three front systems can go pretty deep into the bass, but the very deepest bass is still shunted to large Velodyne and SVS woofers in the two front corners of the room. A big Rane equalizer fine tunes the response to within 2 db between 90 Hz and 16 kHz. If you look above the big window you will see a black-colored housing that can lower a 4×8 foot front-projection screen. The projector further to the rear of the room, out of the photos. A third photo is posted to show the equipment rack for this installation. Power to the center and system control is via a big Yamaha receiver, although power to the IC-20s comes from a big Carver power amp. The center speaker is biamped, with a 260-watt total feed. The total installation power is in excess of 2000 watts.
I have published over 200 audio magazine articles over the years and authored four books dealing with audio-video and recording quality, as well as helping to write and edit the 2005 edition of The Encyclopedia of Recorded Sound. In all my experience, this 8.2-channel installation is the best I have ever heard, period, with the center unit that I built easily able to run with the big main speakers.
Added two more photos. One is of the new equipment rack. I downsized by removing some processors, the old laserdisc player (it was moved to my smaller system), one of the two DVD players, the Carver power amp, and the crossover network for the second subwoofer. The second subwoofer is gone, too, and put into storage. The downsizing was done for the sake of my wife, who would be utterly at a loss with what to do about servicing the stuff if I kicked off. The wife also replaced the couch and chairs, and the new photo shows them, plus the way the room looks with the drape pulled and the projection screen pulled down. The left-rear part of the room is also now shown. The small TV on top of the shortened equipment rack is a portable that we can move anywhere in the house to view. Use it mainly for late-night TV and newscasts.