Super Tweeters

you may also look " home" for some JBL 2405 and with 2uF cap in series you can hear what it is all about.....

Super tweeters need to be design for particular loudspeaker used not just off the shelf one size fits all. More to it than just setting a box on your loudspeakers and saying good enough if you understand how they interact with the rest of the loudspeaker you would know I speak the truth. But posting such isn't what you all want to hear so it will be ignored. Forum posters want someone to agree that what there doing is right and generally only consider posts that agree to be of use. Sometimes I wonder why I bother so happy listening slap that ST on top its all good.

Johnk,
To begin with, a lot of these supertweeters do have adjustments on them, and since you are only augmenting the highest frequencies that are likely not even being produced by your speakers tweeter, it is not like you were adding a "super midrange" (if such a thing existed) which would cause all sorts of problems obviously.
In the end, many have found them beneficial to the whole sonic spectrum, and if that conflicts with measurements that say it shouldn't be so, who really cares, except apparently yourself.

I think that these super tweeters are helpful to the aging population of hi-fi hobbyists. As we age (50+) we loose some high freq. hearing ability. These ST replace what we are loosing, and we like it. We should all set up our systems the way we like them. If we then tire of it, we change it. If you strive to maintain perfectly flat response and end up with a perfectly "flat" sounding system, you will probably start to explore areas of improvement for yourself.

Can cause destructive interference due to to far a distance between drivers and from drivers covering some of the same frequency not to mention the time error. Then you have the very limited efficiency of most ST again not going to match your loudspeaker unless both are designed as a whole. A driver doesn't allow you to hear ranges your not capable of hearing if they could there would be no hearing problems for one could just use a aid and wow you hear normal doesn't work like that. Last I post good luck.