Super tweeter for FullRange Driver


I have a pair of Audio Nirvana 15in Alinco Classics that I just got done getting into cabinets. After some listening impressions, I've realized I cant live with the high frequency response these things put out by themselves. They only go to about 15k hz. and it's made music lose its sparkle and sense of space and spacial cues. I was thinking of buying a pair of Fostek T90As and pointing them at the ceiling for a more even dispersion and better integration with the Audio Nirvana driver. My main question is what  capacitor volume would you suggest? Where in the frequency response would you crossover to the tweeter? Would wiring the 8ohm tweeter and the 8ohm Audio Nirvana in parallel make me need to change my amp(Audio Note Kit 1 300b Set) from 8ohm to 4ohms? Any other brands of tweeters recommended for a fullrange driver that is around 96bd efficent? Sorry for all the questions, incredibly new to trying to implement crossovers with full rangers. If this sounds like a bad idea. Please speak up. 
akwilson501
cabinets. After some listening impressions, I’ve realized I cant live with the high frequency response these things put out by themselves. They only go to about 15k hz. and it’s made music lose its sparkle and sense of space and spacial cues.

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Yes correct,
A high tech WBer 8 has highs to 12khz+, but its also nice to add the 12k-15khz sheen, glimmer, sparkles.
I don’t like super tweets, planar/nor ribbon tweets.
I plan to add a
DavidLouis clone of a famous Beryllium tweet, has a incredible neo dymium magnet motor.
Under $200,
Running a fantaistic 3.5 inch paper tweeter w a  2.2 Mundorf cap, Cuts off like 9khz,,,
so there is a overlap in fq's at 9k-12k, or what ever fq the DavidLOuis VX8 rolls off, I have no idea. 
I/m willing to fork out $200 to try the Be tweeter. and will post a note on its performance. 92db sens, same as the paper cone tweeter.

Hi @mozartfan ,

I you use 1st order, you will hear your supertweeter in parallel with your speaker 3 octave down crossover frequency.
It can cause modulation distortions in upper midrange where our hearing is very sensitive.
3rd and 4th order work much better for supertweeter. 
I did 1st order and 4th order with the same speakers and supertweeters. When I moved to 4th order I got much more smooth, detailed, and clean sound in the upper midrange. Much less brightness, harshness, graine. It also afforded me to increase level of upper high frequencies (over 12KHz).

https://www.calsci.com/audio/X-Overs4.html
https://www.audioholics.com/loudspeaker-design/filter-crossover-types-for-loudspeakers

Regards,
Alex.
My Vandersteen speakers have an additional rear firing tweeter that is adjustable/off.   Using the tweeter, it sounds bigger, but the pinpoint imaging is gone. Off for me is preferred.
String - Me 2, flat to something like 30 khz, 100% out of phase distortion that some find attractive in an overly dead room, or a standup cocktail party…..no sweet spot there….
My primary speakers for years in my 2.1 channel system were a pair of Voight Towers with Fostex FE-206 full range drivers. I added a Fostex FT17H Horn super tweeter to the speaker just to see if I could expand the soundstage a little more. I had already added a small Martin Logan sub that worked really well with the FE206s. I followed the Fostex recommendation and only added a 1.0uf capacitor ahead of the FT17H. Much to my surprise, adding the tweeter did make a difference. The best way I can describe the change is the soundstage ceiling (I see it as a sound field bubble - I know that sounds weird) was higher or more expansive in the room. That sound field bubble was larger and made the previous field seem cramped by comparison. 

I no longer use the speakers. My son and his roommates are enjoying them at university now. They aren't focused on quality of the sound, but they love how loud they can play!

Cheers!