what are the thoughts of stand alone super tweeter

I have been using speakers that extend well above the audible range since the early seventies and am convinced that it is a definite benefit. BUT I think you are letting yourself in for a lot of trouble. Unless you are going to get a good electronic crossover and amplify the tweeters separately OR you are or have access to a talented crossover designer the speakers will probably sound worse. The tweeter has to be very carefully integrated with the rest of the drivers and this is the thing that separates the men from the boys in speaker design. Years ago I owned a pair of B&W P2H speakers [their first product]. This used what may still be the finest tweeter ever massed produced, the Ionic tweeter. This was marketed in different countries with different names[ theirs was the Ionafane] . It was totally massless , flat out to 30 or 40k and glowed with a blue light. It was about the neatest thing I ever saw in audio and it sounded wonderful. But even B&W did not succeed in matching it to a cone driver. If I wanted more extended highs I would change to different speakers as I think it will be cheaper and easier in the long run.

I am well aware that the Ionic driver was not a super tweeter as such. My point was that it went out as far as a typical super tweeter, did not require a crossover to a tweeter as it went low enough to mate directly with a cone woofer/midrange but still , despite the best efforts of B&W, was not totally satisfactory. I have seen any number of revolutionary tweeters and super tweeters come and go over the last 40 odd years. The problem has always been matching them to the rest of the system. My speakers are also flat out to 25k and I must admit to being puzzled as to what extending it to , say ,40k would achieve. I would not be the best judge in any case as my ears will no longer hear 16k.

I am having trouble with the concept of " having no music they reproduce" . Surly they must be reproducing the overtones of music in the audible range. Otherwise we left with the notion the simply stimulating our hearing beyond the audible range is somehow pleasurable. I have been using Spendor speakers [as well as many others] since 1971 and I well appreciate the value of a WELL Integrated super tweeter. At this point I declare "De Gustibus Non Disputandum Est" and retire.

It might be helpful to look at the paper by Martin Colloms on his web site. He is the author of HIGH PERFORMANCE LOUDSPEAKERS as well as being a speaker designer and audio critic. It is too long to reproduce but in part it states:

2.5 Anecdotal Consumer Press Reporting
I have considered that informal, anecdotal reports from reviewers concerning the advantage of addon
super tweeters to be rather suspect since I feel that generally the basis of their evaluations has
generally been so flawed that the results may be discounted. The difficulties encountered are
manifold and only a few need be considered to confirm my negative view. Firstly the test for
response extension benefit will only be valid if the extended response is achieved without affecting
the performance in the existing ‘audible’ range.
Testing for a subtle effect, which may well be barely audible, is a manifest nonsense if it changes
the uniformity and loudness in the already operative treble range. Yet this is what is happening in
these tests. So far, no commercially available add-on tweeter and matching crossover can avoid
this fundamental error. Note that when such a driver and crossover is patched on to an existing
audio chain, as it often is, it will inevitably change the loading on both the cable and the amplifier,
and thus very likely impart another audible difference.
These ‘super tweeter’s typically operate in parallel with the existing tweeter over about an octave
bandwidth, and may destructively interfere with the primary tweeter output. Thus there is a potential
to impair as well as alter the results. Sadly, some critics are so pleased to have heard a difference
they are tempted simply to judge it as an improvement. Often the crossover is a simple capacitor
feeding a metal dome tweeter, perhaps with a beryllium composite diaphragm. Such a crossover is
something of a disaster since a calculated 20kHz ‘crossover’, comprising a single capacitor for a
nominal 5ohm rated tweeter, provides the response shown in Figure 1. The intrinsic output is
compared with the crossover objective, which is seen to be markedly different from the practical
result generally obtained with such a single element filter. The cause is the complex impedance
presented by the high frequency driver compared with a plain resistor load. Even with more
complex, higher order filters, the practical crossover points for super-tweeters are often placed well
into the audio band. It is not surprising that audio professionals dismiss such published subjective
results, which often seem to be produced in support of media and equipment marketing.

In my last post I failed to give a complete guide to the article. It is Archive A10
DO WE NEED AN ULTRASONIC BANDWIDTH FOR HIGHER FIDELITY SOUND REPRODUCTION?
Martin Colloms, Colloms Electroacoustics London, 2006
It is found on the AUDIO CRITIC magazine section of the web site.

My Doctoral research area was the History of Science , I also have a Graduate degree in Theology from the University of Chicago. I consider myself somewhat knowledgeable about what constitutes an observation. Raw sense data is in no way an observation in a scientific sense. If you tell me that we have a product that 1. Plays no music and 2. Is inaudible and 3. In some inexplicable way makes the music better , I will say that you are in the realm of my other field, i.e., Religion, where belief in the power of unseen forces is prevalent. I am sure testimony such as yours would be admissible in witch trials but hardly in scientific enquiry. Your dismissal of Colloms would have been more convincing if you would have pointed out where he was wrong. You did bother to read the article didn't you?

I also studied psychology, undergraduate major , Graduate work at Chicago and 2 years of Psychoanalytic training and I recognize certain symptoms in your responses which lead me to the conclusion that it is you who cannot brook disagreement with the conclusions you have already reached. When your pronouncements are questions you descend into name calling. If you do not care what I think why are you so upset about it? I will not enter such a contest as vituperation is not one of my skills. I will only point out that what you THINK you hear is not data and simply declaring something to be so is not making sense of it.