what are the thoughts of stand alone super tweeter

Mlsstl is correct. In addition, note that, since you cannot hear above 20KHz, the interactions he describes will be the dominant effects of adding on the supertweeter.

Kal

At my age, approaching big five O, I appreciate a great mid-range much more than a good tweeter. So super tweeter does absolutely nothing to me.

Unless you are young and have 20/20 hearing, IMHO, don't waste time and money on super tweeter.

Years ago at CES Murata demonstrated their supertweeter. Listeners heard a musical passage without them and then again with them. The passage had more air, sparkle, and life with them. As we were all murmuring about how something that has no response below 15K Hz, someone thought to ask to hear the Murata by themselves. The guy running the demonstration said, "You are." We all focused on what we were hearing. There was no music to be heard, only zips, pops, and tizzes. I was very difficult to believe this would add to the sound we had heard. He reran the demonstration and again the Murata's benefits were undeniable. I bought a pair on the spot.

Initially, I had Beauhorn Virtuosos with Lowther single drivers. The Muratas did wonders with them. When I sold them, initially I just set the Muratas aside thinking that I would probably sell them. Much later after I got adjusted to my Acapella LaCompanellas with frequency response out to 30K Hz. Out of curiosity, I decided to try the Muratas with the LaCompanellas. They had the same benefits with the LaCampanellas! I have repeatedly to find where they add to the sound. I have them outboard of the main speakers and 36" up from the floor.

I have a friend who says the Townshends are better, but I will probably just stick with the Muratas.

There is some research that would suggest that although your ears probably are lucky to hear up to 16K Hz, that high end extension to 100K Hz does register in listener enjoyment of music. I strongly believe this is so.

I think that you should have no response below 15K Hz in a supertweeter.

"There is some research that would suggest that although your ears probably are lucky to hear up to 16K Hz, that high end extension to 100K Hz does register in listener enjoyment of music. "

Correct. There is some research but it all comes from one lab without, to date, independent corroboration.

Thg said: "I think that you should have no response below 15K Hz in a supertweeter."

While that is a nice sentiment, it is highly unlikely.

The Murata is rather vague about its crossover mechanism but if its range is given as 15KHz and up, it almost certainly has output below that (just like the other two supertweeters mentioned.) If it is a simple capacitor, the crossover slope would be 6 dB. Mechanical characteristics will likely add to that slope at some lower frequency but we don't know where that is.

If it is a 6 dB slope, that means output could only be down 6 dB at 7500 Hz.

Even if there is some super-high frequency magic taking place, it is pretty easy to see there is also a fair amount of energy being added in frequency bands that are already being serviced by the main speaker.

Back when I worked in a stereo store in the 1970s almost all equipment had tone controls. It was nearly universal for a customer (regardless of system, age, type of music or any other factor) to turn the treble up a notch or two. They just liked the way it affected the sound.

I hardly find it surprising that an add-on tweeter that clearly has output in the 10KHz band (even if the specs indicate it starts higher) is going to be audible.

There is an old saying that when you hear hoofbeats you should usually think of horses before you start looking for zebras. Maybe there is a zebra out there at 40 Khz but I sure see a lot of horses in the clearly audible 10KHz to 15Khz range in all these products.