I'd love to hear anyone's thoughts on this. Is there a flaw in my thinking?

I'll take exception to your proposed design. A curved array is not necessary if your line array operates in the near field.

Line arrays that are sometimes curved to yield good sound to a wider audience. Pro sound arrays use a J shaped curving to establish the close listeners in the near field and then fire the far field over their heads to the cheap seats in the balcony. Hence, the goal fot the J curve is to broaden the dispersion to the audience.

The line array curving that you suggest is a concave shape that limits the effectiveness of a near field line array. With this approach you severely limit the sweet spot area. Such a design will localize the listener at the focal point of the line curvature for proper sound. No where else in the room will the sound be correctly focused or balanced.

My solution is to design the line array or source with a flat baffle but place the listener in the near field of the sound. My white paper describes the criteria for near field operation of a line array. In the near field the sound radiates outward from the source parallel to the planes of the ceiling and floor. Thus, little sound energy impringes off of the ceiling or the floor. Effectively, the listener will hear only the sound localized in the horizonal plane wherein he is listening. You can do deep knee bends or stand on your tip-toes and you'll hear the same sound--the vertical coherent wavefront extends from the bottom of the array to the top of its active radiating area. Hence, once you have established a near field situation for the listening area, then you have no need to worry about the various distances from the drivers in the array to the listener. Take a look at Figure 2 in my white paper and you'll understand that the coherent sound front travels for a near field array. The sound doesn't overlap so you need not worry about different sound paths from the top and bottom of the array.

Finally, you need to understand that our ears accurately locate sound direction in the horizontal plane because the shadowing of the head helps to discern direction. In the vertical plane sound localization is less accurate because our ears are in the same plane. The Haas effect also comes to contribute to minimize smearing.

Bottom line is that curving the front baffle isn't needed for near field listening. The sound will be correctly balanced for sound staging and imaging throughout the listening room wherein the near field exists. You can listen close to the sources or farther away and still hear great sound. A slight power taper may help balance the in-room power response from the ends of the array.

Jim

You can do whatever you wish on this subject but I think that a stepped baffle isn't necessary. My reply was more directed toward a focused baffle than what you are suggesting. But I'm pointing out that it isn't necessary to step the baffle and in fact might lead to lower sound quality as you distrub the wavefront. I'm not buying the sound smearing issue that you raised as I believe that you don't have it in the vertical axis near field as I wrote in my earlier reply.

Jim

By the way, do you have any thoughts on how the new CSS WR125ST would work in an array? I'd like to build using high-quality components to get a very high performing speaker, and have my eye on the 16-ohm version of this driver, to be paired up with an array of either BG Neo3 or Fountek JP-2 tweeters. The link for the CSS driver is:

http://www.diycable.com/main/product_info.php?products_id=533

Thanks,
Dave

I like the looks of the CSS WR125S and ST drivers. The initial reports from others are favorable. Al Wooley and CSS have demo'ed some line array models (with the WR125 drivers) and I suspect that they will be sold as kits in the near future. Most initial reports on sound quality that I have read on these designs have been mixed though but I would guess improvements are underway.

The Fountek NeoCd2.0 ribbon (replaces the JP-2 version) would work great in a line array. I'm not a Neo 3 nor Neo 8 fan.

Jim

No issue with single driver, MT, etc. on the WR125 designs--all glowing reports. The line array designs with the WR125's were early models just after availability of the drivers and thus had not apparently reached enough design maturity, I suspect. Again, I'm reporting what I read on the web and not personal listening experiences.

On the Fountek 2.0 version it offers inherent length and minimzes the gaps which would result if you used Neo 3's in a line.

Jim

In the frequency range where drivers operate in a nearfield line array, they are omnidirectional. So the angle of the driver will not make a difference. However the driver will interact with the baffle edges, the steps will make a difference there. On a large flat baffle a driver's wavefront is a coherent semi-shphere. When the wavefront encounters an edge of the baffle it defracts causing interference. This should be taken into account when designing any speaker. On a stepped baffle it will be more significant than a simple box. There will be interference above and below each driver, not only from the adjacent edges but also from the edges further away from each driver.