• http://steinman.mesls.org/stereo/J%20Kalinoski%20Loudspeakers%20066.jpg

While those Fostex drivers are very nice full range devices when used as point sources, they have limitations when you start to array them. My line array white paper (see link) details some of the design limitations.

When you bring two perfect drivers together so that at a frequency wherein they are less than a wavelength (WL) center to center (ctc) apart, then their overall directivity will increase. But beyond one WL ctc, you will start to have declining directivity and eventually at a spacing of 2WL you'll have cancellation.

Bottom line is that a line array composed of full range drivers will not function up to 20,000 Hz unless they have ctc spacing of less than (theoretically) 0.68" which means less than 0.68" diameter drivers spaced with their flanges touching. You can almost get by if you use less than 1.36" drivers on the same centers as the ears have less sensitivity in the 10-20 kHz octave.

I have seen and heard a line array composed of 2.125" drivers spaced 2.125" ctc and it took a lot of equalization to get the upper octave to sound right.

What I suggest is that you think of a two-way design that adheres to a crossover based upon the ctc critieria that is outlined in my white paper. That works.

Jim

• Near Field Line Array White Paper

• http://www.audiocraftersguild.com/Xtreme/xtreme.htm

One tweeter would work but recognize that you would have your woofers in a line configuration and the tweeter as a point source. Nine of the 8inch woofers would create a near field over much of your listening room while the single tweet would be a point source. Sound fall off would be 3 dB per doubly of the distance from the source for the woofers while the point source would fall off at a 6 dB rate. If your listening distance were fixed, you could balance the sound but if you wish to have well balanced sound throughout the room you would need a line of tweeters (long enough to create a near field).

Jim

That Fostex F200 always reminds me of the JBL 2115, which was an absolutely awesome 8" driver of the 1980's. The driver was flat over an amazing range, from 30Hz to 10kHz. It had a shorting ring, so distortion was very low. The shape of the basket, the brushed finish and shape of its face, the cone, surround and voice coil cover were the same. So I'm thinkin' the Fostex F200 must share a lot with the JBL 2115 more than just looks, and that leads me to believe it must be an excellent part.

Have you ever seen or heard a JBL 2115?

• JBL 2115

• http://www.imz-ural.com/gearup/#

• http://klangfilm.chez.tiscali.fr/

I've been meaning to do that ever since I noticed the similarity between the F200 and the JBL 2115. I was disappointed when JBL discontinued the 2115, but it didn't really fit in their 20xx/21xx/22xx/24xx product lineup, so I think that's why they moved on towards midrange products of that size. The 2115 is truly a full range driver.

I appreciate your enthusiasm about the F200, but don't discount the 2115. JBL's engineers really do their homework and that 2115 was the best driver of its type I've ever heard. I'll check the F200 and see how close they've come.

Thanks for the heads-up; I think I'll really enjoy the F200.

• http://www.audiocraftersguild.com/Xtreme/xtreme.htm

I know that Fostex makes good products, 'cause I've heard some very nice sounding Fostex speakers. The single driver speakers I've liked the most in the last couple of years have used Fostex drivers. Who is doing their engineering over there? Do you know who any of the people are doing R&D at Fostex? I'm thinking there must be some clever folks there because they have made some very fine speakers.

That's one thing about JBL, their R&D team is comprised of some very good engineering talent. I'd say they've kept themselves in pretty good shape as far as advances in technolgies and materials are concerned. The list of engineers and people involved there reads like a "Who's Who in the Audio Industry."