Thoughts on adding a Super tweeter .

The super tweeters I tried were custom built, and they had an adjustment knob on the back of the module which either changed the volume or crossover point, I'm not sure which. I definitely had to adjust the super tweeter to find a point at which it blended nicely, but I was able to find a point at which the blend worked very well.

So, I would highly recommend a super tweeter with an adjustment.

Tom Port uses Townsend Supertweeters on Legacy Focus speakers. He brought over just one and attached it using duct tape at the inside on my right channel Focus speaker at the level of the existing ribbon tweeter. We listened to vinyl and immediately heard the increased airyness of the recordings. The speakers disappeared with the supertweeter (and I have Hallographs behind the speakers in a 25' X 21' X 12' high room with the speakers 6' from walls). If one worked wonders, two should be fantastic. However, the setting was at the low end at 2 (out of 10) because the Focuses are rather efficient at 96 to 98 db/watt. So, this is the first time I've heard a supertweeter blend so well with rolled off speakers (Focuses have a very pleasant rolled off highs, at least the first model from the 1990s did, maybe the new ones have better ribbon tweeters).

No one super tweeter for all loudspeakers, each super tweeter needs to be carefuly matched in level and crossover so no over lap,phase,time problems or boosted frequincys. The one tweeter that matchs all is just asking for grief maybe you will get lucky and it will match but your taking a chance. So if your thinking of adding one realy look into it and maybe DIY or have a pair custom built than you can also match finish as well as transducer crossover.

Most likely the benefits of adding inaudible content are inaudible.

It is known that sharp filters to remove out of band noise can effect the "in band" sound, however, that seems to be the only convincing argument for greater bandwidth (well beyond what you can hear) in audio reproduction.

I love my Fostex F200a Mid matched perfectly (to my ears) with the wonderful Fostex T90A-EX super tweeter, thank you JohnK!

A friend of mine uses the 'Townsend' super duper super tweeter with his horns and swears by it.