I'm not saying that a throat mismatch will sound terrible. The differences will be small. I will say that if we have no concern for the throat angle match, then do we really have any concern for the OS profile? Why not just make it conical and call it a day?
Originally Posted by MBentz
The OS math is only valid for frequencies where the wavefront is planar. So with that in mind, the whole throat angle matching concept is only valid at the lower frequencies where one might argue the issues of diffraction are less severe. Btw, you see this behavior in the measurements. Anyways, I agree that the throat matching is blown a bit outta proportion. In fact, since the higher frequencies aren't planar, by definition you don't want to be perfectly matched...
The SEOS is a compromise just like the JBL's biradial diffraction horns in the K2/Everests are a compromise. The SEOS primary concern is smoothly transitioning the throat's diffraction to the conical section to the mouth. There is some sacrifice in the upper frequencies (~10khz and up), but IMO, that is a better compromise than the effects of relatively abrupt diffraction at the lower frequencies (~10khz and below).
Different mathematical contours could be used of course and that would show differing effects. The OS contour, IMO, does a good job of transitioning from the CD's narrow angle to the desired wider horn angle. It is a good balance.
JBL uses their 1.5" throat and certain contours to diffract at higher frequencies in a fashion more similar to a smaller throat horn at the expense of the lower frequencies.
They actually detail (to some extent...like most whitepaper they don't tell the whole story) the differences between both approaches as they use both minimally diffractive and overtly diffractive approaches in their PT waveguides.
I've heard the K2s and they are wonderful speakers. Anybody who says otherwise is nuts. I'm not saying they are worth the money or that they sound perfect, but they are without question, well-designed and implemented.
With that said, there are multiple ways to skin a cat.
I can't say if sacrificing the throat angle match would be worth the potential benefits of the NSD1095N (I can't say that there are benefits as I haven't heard them myself...there could have been other things at play causing your preference).
As far as building separate SEOS profiles for different angles. That is not really up to me. Obviously it could be done, but it would likely be a tough sell. These aren't one off horns. There are mold costs and developing a SEOS profile for a CD that is nearly 2x the price of the well regarded DE250 and 4550 in the US is unlikely IMO. I would suggest talking to Erich directly since he is producing them.
I probably won't buy a pair of the NSD1095N since I will have enough drivers to design for and they are too expensive for most people. If someone else wants to buy some and send them to me, I would design a passive for them. I'd also need the matching woofer you intend to use.
BTW, the XT1464 is injection molded polyurethane not aluminum. http://www.eighteensound.com/index.a...roduct&pid=177
The downside is the cost of the 1.4" equivalent to the NSD1095N is probably about 2x the price. The upside is that you can crossover around 700-800hz.