4.5 Inches of Fury- My Single Driver Speaker Project

After stumbling across the Frugal Horn site one day, I decided it would be a cool project to build a set of single driver speakers. Initially I wanted to do one of the double mouth Nagoaka style horns, but couldn't justify the 2 or 3 sheets of birch ply I may waste on my first attempt at a speaker build. Let the idea slide until I came across a guy on Audio Circle selling a pair of gently used Fostex Fe127e 4.5" full range drivers. With the drivers on their way to my house, I decided it would be the right time to find some plans.

Enter the Fonkens. They're near aperiodic monitors 13" tall and about 11 inches deep, using about half a 4x8 sheet of natural birch poplar core ply. The Fe127e is flanked on either side by 3 vertical ports set in the chamfered edge of the cabinet. Being a single driver full range speaker, there's no crossover, resulting in an efficient design without the phase shifts associated with a crossover. At least this is what I read, I liked them because it looked like I may be able to build them.

When I was done, I had about 3 weekends invested in building the cabinets and matching stands, another month and a half of weekends and evenings in finishing them. The baffles are natural birch finished with clear brush on Deft lacquer. The rest of the cabinet would have been the same had my wife, the interior artist and faux finisher, not commented that the end cuts of the ply visible on the chamfered edges made them look unfinished. Five coats of primer, four various color coats, and 7 coats of lacquer later, they're woodgrained to match my equipment stand. She hasn't looked at them since, but I can sleep better knowing my **** matches.

Anyway, on to the sound. Going in, I'd never heard a set of single driver speakers. I was interested at first because they're just about 180 degrees opposite in design from my SDA's (which I still have, everybody relax), and I really wanted to experience something different. Eminent lifestyle changes added fuel to my quest; my wife's pregnant with our first kid so a design that has a bit more finesse and nuance at lower volumes will help me from attaining eunuch status as quickly. First thing I noticed was how revealing they are. I was ready to ditch my turntable the first time I spun some vinyl through them. The sound I had loved was now flat and lifeless, like listening to a poorly recorded cassette tape. Turns out the tracking force on my cartridge was set way too low using the cheeseball system on my entry level Pro-ject table. Setting it with a digital gauge did the trick. Next was the imaging; the soundstage width of the SDA's was gone, but the imaging is so precise. In vocal duets, voices are easily discernable from one another, I can pick out which stringed instrument is playing where much easier in bluegrass numbers. The imaging does get a bit congested as the number of electric instruments increases, which I guess is a drawback attributed to having a single driver playing everything. Bass, while not vibrating your pants, is super clean. Not much information below 60hz or so, though. Anyway, a fun project. I'm still going to do the big horns, I'll just have to bolt them to the walls in the case the not yet born little Washington decides to go King Kong on them.