what are the thoughts of stand alone super tweeter

I tried the Onix supertweeters with 2 models of Alons. Misstl points out the possibility of coherence issues. I suspect the whitish coloration I heard in the highs was a coherence issue, super tweeters may alter the tonality of your loudspeakers.

YMMV may vary with different super tweeters and/or loudspeakers.

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.

Stanwal, the Ionic tweeter or Corona or plasma, is not a supertweeter. Many come well down into the audible range. I think there is a good reason to distinguish tweeters and supertweeters. The Reference 3A Grand Veenas, have both tweeters and the Murata supertweeters.

I do entirely agree about mating plasma tweeters with other drivers. Acapella uses the plasma in every speaker above the LaCampanellas, which I own. In all but the Trilon at $160,000 this tweeter stands out as exceptional and draws your attention to it alone. This is the reason I bought the Acapellas that I did.

Sns, again I think my satisfaction with the Muratas comes from them not reproducing music. They only begin to come into play at 15K Hz.

You can find these on ebay called the ionovac by Dukane. Here in CA my city has probably more per capita then anywhere else in the USA. Five of my friends have a pair of them, one two pair. They stopped making them due the need to use certain chemicals. Me, I prefer the Maggie ribbon. But, the ionovac sounds good when set up well. jallen

I use the Radio Shacks for all my systems, including the reference system. Its very efficient, you can pad it down with a resistor.

Peter