SUPER TWEETERS-anybody heard them?

I just checked out information on the Tannoy supertweeters, and was surprised by the high price. Considering that you can get a decent tweeter that goes to 20Kc for $100 or less, why should it cost so much more to extend to 30 or 40 Kc?

Seems to me that piezoelectric technology is perfectly suited to this application, and piezoelectric supertweeters are made. Their low cost may be an embarassment, but do they do the job?

Viridian...thanks for the info. I figure the wavelength of a 30Kc signal to be less than 1/2 inch. Even if the Piezo driver were perfect regarding phase, how could one ever get it time-aligned with the other drivers of the system? Maybe the phase problem isn't important.

If I were to try out a Piezo, is there one brand that you would suggest? I would just hide it behind my MG1.6 speaker, and bounce its sound off the ceiling.

There seems to be a related effect at the other extreme also which has been noted with RELs Sub design. Even though we do not actually hear the effect there are things happening below both thresholds of 20-20K.

Here is a dialog taken with the REL Designer.Sorry this is getting away from the question,but both extremes should be explored I thought. Having true intergration must be addressed using either exterme I imagine.If not I would think there would be unwanted overhang which would muddle up te effect or benefit of using a either a Super Tweeter or Sub-Sub Woofer!
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This is to answer to a question I think sbg had about the article I had alluded to in a thread about Bass Reproduction with subs. The initial question I had was why most speakers that were on the market could not have the kind of extension I would want .Another words Full Range for an affordable price. There are a few exceptions like speakers from VMPS. This is the article I had mentioned.It was from ABS not S-phile.

If it was not sbg then excuse the reference to him.
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The Absolute Sound –Feb.\Mar. Issue P.73 of the Kharma Ceramique Ref. Monitor 3.2 review by JonathanValin

Putting aside enclosure and room-mode issues, with a large multi-way you are confronted with the problem of trying to make drivers of unequal size ,mass and material composition sound like one unit. Though crossovers are theoretically designed to do just that, anyone who has ever yoked subs to an electrostat or good mini-monitor can tell you that what’s true in theory is not true in fact. Just listen critically to the midrange of any such speaker before and after you’ve added subs.I don’t care what sub it is or what slope or filter you apply; you’re going to losse something in the way of soundstaging, transparency, dynamic speed, dynamic speed and nuance, and inner detail—in short, you’ll lose a significant amount of what you bought the the speaker for.(Of course you gain something , too,in the way of body ,midbass authority, instramental weight, and low bass extension but let’s not pretend that these things don’t come at a cost that some of us are unwilling to pay)

http://www.audioasylum.com/audio/speakers/messages/118672.html
http://www.audioasylum.com/audio/speakers/messages/118930.html

Regarding Low Frequency...In any large hall used for recording there is a very low frequency rumble that is always present even when the musicians have gone out to lunch. It represents the natural frequency of the hall, and is excited by such things as the air conditioning system and passing road trafic. This subsonic noise is plainly audible on some recordings if you have suitable speakers and you don't activate your rumble filter.

But is it "noise"... something undesirable. It can be argued that this "hall sound" is part of the musical experience, and reproducing it adds to the realism of the recording. I find that is true for some recordings and not for others, probably depending on how severe the background rumble is.