Are my " diamond " tweeters really diamond

geof 

Tell me how you super glue those zircons. Sounds like a good business model. We could have that done in China and bring them over here and really mark them up. 

I have never heard any improvement in sound. I much prefer a nice soft dome tweeter. I may be old but those tweets that go way up in  the frequency range make me edgy and nervous. I think it is the distortion or break up at " inaudible frequencies " really can be perceived.

I've heard a few soft domes that sound bright and edgy (for example, some from Polk) and metal domes that are smoother than a typical silk dome. Some high-end soft domes break up under 20 kHz. Why do they not sound edgy? Because it's all in the quality of the parts and implementation. I think many mistake upper midrange distortion as tweeter breakup.

@helomech 

I fully agree with you but I see where this is going... Well, there are many non-diamond speakers out there as expensive (or more expensive) than their diamond competitors. Manufacturers are always looking for improvements and pushing each other. Call
it hype if you will, but my ears never heard as good speakers as we have nowadays (diamond or not) and the best ones are unfortunately big, heavy and quite expensive, regardless of the material used for their drivers. Such is life...

@luizfcoimbria,

Sure,  there have been advancements in some areas. IMO, the greatest gains have been in small, budget speaker performance. It's easy to make a large, heavy, cost-no-object speaker sound great. It doesn't have to push the boundaries of physics. 

The best speakers I've heard to date don't use any esoteric materials or cabinets. In fact, they're simply updates of 30+ year old designs. For example, Stirling Broadcast's LS3/6. They use a plastic dome super tweeter with a published frequency roll-off point of 17kHz. Many audiophiles would see that number and immediately dismiss the speaker as inferior. They'd assume these speakers lack detail or "air" compared to those equipped with a diamond or beryllium tweeter. Yet, IME, these speakers have greater resolution and detail than the B&W Diamond series and other highly regarded brands. 

So true. Not all soft dome tweeters are good. Speakers have to be voiced. Makes me wonder who they are voicing these things for. Certainly not me.