|Project by ferstler||posted 11-02-2009 12:52 AM||2146 views||3 times favorited||11 comments|
For years I had a pair of Allison Model Four bookshelf speaker systems hooked up in my smaller AV installation.These had been used as surround speakers and to tell the truth they were simply overkill for that job. Worse, because of their size both the wife and I have occasionally bumped our heads on the things. Great speakers, but out of place in that particular room.
The replacement units that I just completed are far smaller; each about 1/3 the size of a Four. They weigh 13 pounds apiece, and each uses two 4.5-inch midrange drivers on top, facing upward, with genuine Radio Shack tweeters on the angled panels. Actually, they are shaped like miniature Model Fours, although their finish is quite different.
All of the panels are mdf, with the oak-finished ones actually vinyl veneer. Hey, don’t panic, yet, because it cost me about six bucks apiece to build the things! I had the wood on hand (the oak finish stuff was cut from vinyl shelving I had left over when I downsized some equipment racks a while back) and the mdf was left over from the earlier speaker projects. The chokes and capacitors in the crossover network were just sitting in my parts bin, as were polyswitch bistable resistor fuses that protect the drivers from electrical overload. The speaker drivers were left over from projects in the past, too. All I had to purchase was the 5-way binding post cups for the hookups in the rear and the black paint. Even the grill screens were cut from old Allison speaker screens I had on hand. The edges of the units still need a couple of coats of satin black paint to smooth them, but otherwise the finish is done. I’ll do that recoating down the line, but there is no rush. The speakers are essentially finished.
I use an AudioControl RTA to evaluate speakers (both those I used to review for magazine reports and any that I build myself), and I temporarily set the new units up as main speakers in my larger system to check their absolute performance before setting them up as surround speakers in my smaller system. They measure nowhere near as smooth as the Model Fours they are replacing (the Fours have been a kind of reference standard for two-way speakers for years), but for surround-channel duty they are fine, and when I listened to them as a stereo pair as part of my “voicing” work they actually sounded quite good. The angled-panel design, delivering the resulting spaciousness, somewhat offsets the less than perfect curve flatness. Actually, their measured curves were better than some I have run on assorted systems sent to me in the past to review for magazine reports.
While this project was anything but a woodworking challenge, the result was surprisingly workable (and notably low in cost!) and now all I have to do is sell those spare Model Fours. I already have two offers, because they are cult classics. Hey, don’t worry about me shortchanging myself. I have four additional Model Fours in my larger main system in another part of the house doing surround-channel work there. I even did a refurbishing article about them here a while back.
One of the fun challenges with woodworking is using leftover stuff to build useful items on the cheap.