spj@hou3c.UUCP (Stephen P. Johnson) (02/01/85)
Several messages have appeared on the net recently asking about Speakerlab, and I presume about building one's own speakers. Speakerlab is still in business, although the complexion of the company has certainly changed since the early seventies. I can't evaluate any of Speakerlab's recent kit offerings because I haven't heard them; I did however, build a pair of S4's and a pair of S7's about ten years ago. I also bought some raw drivers from them last year. Anyone interested may want to look at Consumer Reports, as they have reviewed some Speakerlab offerings, which fared only moderately well. Speakerlab drivers come from two sources; they make some woofers and cone mids, and they buy dome mids and tweeters from other makers, mark them up, and resell. The Speakerlab woofers I bought have huge magnets, unfortunately, they must have poor quality control, because one of them was defective when I got it. They refused to replace it with a new speaker, they rebuilt the cone, and sent it back. The basic parameters (Electrical and mechanical Q, resonant freq. and compliance) of the "pair" of woofers were so dissimilar I had to do extensive reworking of my Thiele-Small designs to get the left and right bass units to be reasonably well matched. The mids I bought are OK, but now I know they were overpriced. If you want to build your own speakers, and save money, get a subscription to Speaker Builder magazine, and peruse the Journal of the Audio Engineering Society at a good tech. library. Look in the back of Audio, Stereo Review, or Speaker Builder for some reputable driver supply houses like A&S and Madisound. For a first project, build a two way speaker with a 6 1/2" or 8" woofer and a dome tweeter. Make sure you get a tweeter with ferrofluid in it. It will handle a lot more power, and have a smoother impedance curve, which simplifies crossover design. Use an 18 db or 24db per octave crossover (See J.A.E.S.) If you are skilled at evaluating drivers, you MIGHT be able to construct a good 6db per octave system, but the demands on the drivers are EXTREME. Good brands of drivers are Dynaudio (great tweets and mids), Morel, Audax, Seas, Becker, and Peerless. Remember, you get what you pay for. A top notch tweeter runs $25-30, and a top notch 8" woofer will run about $30-$50. I recommend that beginners buy their cabinets ready made. Audio Concepts sells a nice line of blank cabinets. A pair for the two way system is about $90. It's also fun to make your own cabinets, which really isn't too difficult, but takes a lot of time. I like using exotic veneers for my speakers like rosewood, lacewood, and Macassar ebony. Stay away from mitered corners on your cabinets. They are difficult to cut without a tablesaw, and aren't very strong (unless you use splines). A good rabett joint is much stronger, can be easily made with a router, and will be covered by the veneer anyway. Is there any interest out there in building speakers? If so drop me a line. Steve Johnson