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
@akwilson501 === (They only go to about 15k hz.) --
 How you know you driver go to 15k hz ? and what is level -10 db or more?    The sparks is 9-10Khz. 15Khz is not listenable and just add more air. To add super tweeter and make pretty flat response ( not to bright) is very complicated, You have to use you ears and also measuring
tools
You might want to check your hearing first.  I bought a nice pair of VIFA super-tweeters and didn't notice any difference.

Ran the test cd that came with them and found that I no longer hear anything over 12 kHz.  :~(

Fortunately I was able to re-sell them for what I paid.

Disappointing.  I was looking for a little more shimmer on cymbals.
akwilson501

How many hours have you logged on your AN Classic Alnico's? I have owned mines over 9 months and they will improve dramatically over a 3 month period and will get even better with more use.

These AN have more clarity and transparency compared to a previous speaker I owned with a frequency response of 20 Hz - 40 Khz and I haven't noticed any sound degradation, they have the ability to sound live and natural...

Wig