SB Acoustics SB29BNC-C000-4 29mm Beryllium dome tweeter w/grille

Still loving these. If you want the SQ of electrostatics without the hassle and the output of AMTs without the diffraction, do yourself a favor and get these. Worth every dollar.

After six months of listening, these tweeters still sound, well, they don't have a sound!
Just fantastic.

My restored Audio Concepts Sapphire II speakers sounded as new, but for more volume I sawed off the top of another pair and made a second 7" Focal woofer enclosure under the Sapphires. But I could not get another 6dB out of the single Focal T120 tweeter.
Enter the SB29BNC-C000-4. At 95dB sensitivity it's 6 dB higher than the 89dB single Sapphire so no attenuation needed. At 4 ohms though, I had to replace all tweeter caps and coils with roughly double the values, and then tune them. Also added a resonance notch LCR bridge.
The sound is quietly phenomenal. They needed some break-in. After that, they are the best of both cloth and metal diaphragms. They don't really have a sound. Lightning quick transients. Air. Better than the AMT tweeters I have owned. Better than the best of the classic tweeters from the 1990s.
After a week of listening, highly recommended, especially for pre-2000 classic restorations.
A meaty review: https://audioxpress.com/article/test-bench-the-sb-acoustics-sb29bnc-c000-4-tweeter