soft dome versus hard dome tweeters

I have berylium tweeters in my Usher Be-718 bookshelf speakers.

The folks who’ve said it’s all about the presentation are correct. I have two pairs of large floor standers that are both unique and outstanding speakers for different reasons. My other two pair are Martin Logan, Summit and Ohm Walsh LE-5.

My electrostatics are outstanding as far as both higher and mid frequencies are concerned, they sort of excel in that area.

Not kidding, or even exaggerating, the Be-718’s actually do violins better than my electrostatics. It has everything in the world to do with how that sexy berylium tweeter is married to the woofer, which is apparently the same model they put in their big daddy floorstander model. And a few other things about the speaker in general, but the point is that an exotic feature like that, of course, isn’t going to really shine if it’s not in the right company, including what’s driving them. Because all the reviews said the BE-718 is an exceptionally good speaker, but when you drive them with the right electronics that that’s when you will go Wow. I definitely concur.

They’re able to create such a deep and also solid bass response with some pretty amazing dynamics for such a small speaker, that I've never even bought a sub for them, which is hard to believe but completely true. I never intended to run them full range only without a sub, but apparently they’re that good. 

The sexy berylium tweete kind of accentuates everything else that’s there, kind of like icing on the cake, imo. This review corroborates:

https://www.soundstagenetwork.com/revequip/usheraudio_be718.htm

@erik_squires 

I'm all about that midrange too. But a lot of tweeters go a significant way down in to it. And, how that midrange marries to the other frequencies matters. So, what's the best approach to a coherent, uncolored, beautiful midrange?

It would make sense to have no crossover in that range. According the chart I'm looking at, that would ideally go from about 250 Hz to 4000 Hz. What kind of a driver could cover that range with a good dispersion pattern? I'm thinking a fairly large horn, maybe 90 degree flare, and a not too big driver. Center to center on the tweeter is going to be a problem, but it might be worth it. I don't know.

I'm currently running 600Hz on up on a CD  horn and it does some magical things.  But I suspect it'd be better if I could get it down to 250 Hz on the same horn.

Maybe the multi entry horns are the answer. It just bothers me that they require holes be drilled in a horn flare that is meticulously intended not to create diffraction events inside. I know guys are working hard to optimize those designs because they feel that point source coherency is worth a little trade-off in diffraction events.

For what it is worth, the KEF Reference series uses aluminium drivers and aluminium coils.

According to KEF's white paper, the ideal tweeter dome shape for best dispersion is spherical, but the best shape to resist distortion in pistonic motion is egg-shaped.  So their tweeter has both, with the ovoid dome inside the spherical, touching at the top.  They join again at the outer wall forming a triangular shape, much stronger than the single sheet normally found.

The KEF tweeter is concentrically located in the throat of the midrange which forms part of a waveguide.

The base driver(s) use almost flat surfaces, in part to avoid diffracting the tweeter / midrange output.

I agree they sound very different from Sonus faber - but I prefer to hear the sound of an orchestra accurately re-created

@asctim There is a design called "woofer-assisted wide-band" or WAWB for short.  It's exactly what you describe.  A wide band, such as a 4" driver that has credible output in the top octave along with a woofer that crosses in well below 500 Hz. Check out DIYaudio for more information. 

There is a design called "woofer-assisted wide-band" or WAWB for short.  It's exactly what you describe.  A wide band, such as a 4" driver that has credible output in the top octave along with a woofer that crosses in well below 500 Hz. Check out DIYaudio for more information. 

@erik_squires (or anyone).  How do they keep those full range drivers from beaming above 3000 hz or so?    I love the concept of no to minimal crossovers, but, don't they tend have pretty narrow off-axis response?