Mark is chashing the Holy Grail of FR, with the chaotic radiation (bending wave) is well controlled such that the cone diameter shrinks with frequency increase with the dome last to go chaotic (as do similar size shape material character common domes). A measure of how well this is done is how well controlled the HF extension is. A designer can add damping for more control, ending up with the “vintage” top in the A10/12p. A good comparison is the paper A10p vrs metal A10.3.
dave
dave
Do we not have a virtual dome tweeter, perhaps surrounded by a wave guide of the rest of the cone, at those frequencies then?
Pretty much the same thing as a separate tweeter, that happens to be mounted as close to the physical center of the next driver down as is possible.
If you look at the dome of a MA driver, you'll see it's far and above something just stuck on there to cover the voice coil motor...
I suppose the dome of a real tweeter doesnt go into bending mode nor "chaotic". Because its a separate component, it must be a perfect piston or behave in some more idealized way in that last frequency decade, right?
The dome breaks up the same, just higher in frequency and depending on the material. The harder the material, usually the higher the breakup mode BUT the more intense as well. Those Peerless Corundum domes break up past 20k as Corundum is I believe synthetic sapphire like Ruby and Emerald…..very hard. The 33mm one has an FS of like 500hz so it can be crossed around 1k in a not so loud speaker.
Are you saying it’s a marketing ploy?……Ceramic isn’t even on the Mohs scale top 10…..maybe you meant Chromium and AL Ox?
Aluminum oxide is a ceramic material. From a chemist's perspective, "ceramic" is a very broad classification of materials, like "metals" or "acids"... In the crystalline state, aluminum oxide is corundum, and in a very particular state, it is ruby and sapphire.
Some ceramic materials are soft. Aluminum oxide is very hard.
So in the case of fair marketing and transparency, regardless of the crystalline state of the material used in the Peerless tweeters, the dome should have the effective hardness of a material classified Corundum?
I am 99% certain that the aluminum oxide coating used by Peerless, Seas, SB and others is based on anodizing the aluminum diaphragm. Anodize is a process that uses acid to convert the surface of aluminum into aluminum oxide, usually to a depth that is much greater than the normal "thin" aluminum oxide layer that occurs naturally. If the anodizing is thick enough, the diaphragm can be truthfully described as being ceramic, since there is more aluminum oxide there than metalic aluminum. And yes, the aluminum oxide layer is very hard and abrasion resistant. It is not a lie to say it is corundum.
?!? Their specs and the data sheet show 86, or did you mean a different sub-variant?
I've been wondering for some time now why nobody uses cone tweeters. Sure back in the day the dome could sound more detailed or delicate or whatever. But by now I'd think some damn good cone tweeters (or mid-tweeters) could be designed. All the full range stuff I've noticed has low sensitivity though, surely in an attempt to put out "bass" and hence not a good match for woofers. (Though speaker sensitivities overall seem to be dropping, maybe it's not such a mismatch as I think?)
I read the OP's intent as
- Two-way with full range drivers as mid-tweeter
versus
- Two-ways with conventional dome tweeters.
In such case, the Doppler effect should not be so much. Similarly, mid/high coaxials with a separate woofer should not have much problem from the cone movement modulating the tweeter response.
The Markaudio MAOP have a cermaic (Al-oxide) surface layer a couple molecules thick, made by bombarding the cone with an electron beam. Yield is low, the big guys probably look for something more efficient cost wise.
dave