Either Morel or Tymphany. Steve used the Tymphany. I will upgrade mine with the Morels when I can scrounge up more time.
Here is some of what I previously wrote on the subject last year, which is somewhat outdated given the change in models and pricing changes.
The easiest solution here is to find a tweeter reasonably flat on-axis from 8,000 Hz to 20,000 Hz at somewhere between $75 and $150 for the pair. Frequency response and price point rule out many of the soft domes and the metal domes, as well as the horns, ribbons, AMTs, and exotics, many of which poorly or irregularly reproduce above 10,000 to 12,000 Hz. Note that one may pay significantly more or less for a tweeter. Lower-cost comes with sonic abnormalities and spikey response. Higher-cost comes with increased power handling. The ideal tweeter for a standard configuration will have a very low resonance point to permit use of a first-order crossover. We are so far above the resonance point that this is not an issue, but it speaks to better design.
I have read many tweeter reviews, and the difficulty is that drivers come and go with regularity, so some of the best analysis and comparison is now a decade old and obsolete for specific models.
I hesitate to recommend a driver I have not used. as I feel some responsibility if it does not work out. Many vendors, however, will permit you to return a driver for a refund. So you can always try a few and send back the rejects.
The tweeters I was considering, but which I have not tried, are in the Morel line:
Note: the inclusion of a link to a vendor is not an endorsement of the vendor or its prices, and I have no connection to any business. I routinely purchase from Parts Express, an AK sponsor and have generally found its prices to be lower than other sources. I would have used Parts Express for the specifications, except in one case it did not supply the literature.
All of these tweeters use ferrofluid. Like many, I had bad experience with ferrorfluid tweeters in the 1980s, but those dissipated much higher power and were not as well made. I do not know the lifespan, but the reports are in excess of twenty years without abuse. The ferrofluid can be replaced.
For our purposes I suspect these drivers will have identical sound reproduction. The 39 has a slightly flatter response.
We also must discuss impedance compensation. This a fancy name for a filter, either band-pass (LRC) to notch out a resonance peak or a high-pass (RC) to reduce the rise in impedance with frequency. The resistor converts energy into heat. The filter basically is a frequency-dependent resistor, and it is placed in parallel with the driver, exactly like an L-pad. One need not use impedance compensation, of course, many nice-sounding speakers do not. The exact points are determined using frequency plots of the driver.
The MDT 39 rises from a nominal 8 Ω at 8,000 Hz to 13 Ω at 20,000 Hz. This may be tamed with a RC filter aka Zobel. Separate discussion. That's a refinement, and many speakers, again, do not use it. We need not worry about the resonance peak, as energy is not going into the tweeter in that band, as it would if the tweeter were being used in a traditional configuration.
The Morel MDT 39, CAT 298, and CAT 408 are at the approximately price point as your existing tweeter.
As I earlier wrote, I hesitate to recommend a driver I have not used. as I feel some responsibility if it does not work out. Many vendors, however, will permit you to return a driver for a refund. So you can always try a few and send back the rejects.
