The selection of high-quality, sheilded tweeters in March of 1998 was darn sparce. Only one unit from each Seas, Focal and Morel. Vifa was the only player offering 3 choices, the D27ASG-05 (aluminum dome), the D26SG-05 (textile dome), and the Vifa D27SG-05 (silk dome). Unfortunately, none of Vifa’s shielded tweeters include Vifa’s “tinsel leads.” The “tinsel leads” must be more flexible, more resilant to long tweeter dome excursions. All of the non-shielded tweeters that carry this feature rate 100 watts of power handling with a 12 dB/octave crossover at 3 kHz. Similar tweeters without these special leads are also rated at 100 watts, but with a 12 dB/octave crossover at 4 kHz. (It is also worth noting that all 3 shielded tweeters have lower power handling ratings than similar, non-shielded units. I can only speculate the cause; higher expected tweeter power levels in a home theatre environment?) The aluminum and textile dome units have resonant frequencies about 1.5 Khz, so the choice Vifa tweeter was the silk dome unit with a resonance of 1 kHz.
So far I have been able to evaluate the Vifa, Focal, and Morel units. At some point I may check out the Seas unit. It is rather expensive at $64, but looks to be a top-of-the-line tweeter with every bell and whistle that Seas has to offer (even silver voice-coil wire). My final selection is the Vifa, with the Morel being held for further testing (modification of the back chamber for lower resonance).
| Model | Vifa D27SG-05 | Focal TC90KB | Morel MDT-30-S |
|---|---|---|---|
| Pic |  |
 |
 |
| Material | Silk | Kevlar | Textile |
| Faceplate | Plastic | Plastic | Metal |
| Ferrofluid | Yes | No | Yes [?] |
| Resonance Frequency (measured) |
1000 Hz (1090 Hz) | 950 Hz | 700 Hz (837 Hz) |
| Moving Mass | 0.3 g | ? | 0.44 g |
| BL product | 2.7 NA | ? | 3.5 NA [?] |
| Qts (measured) | ? (0.86) | 0.90 | 0.57 [?] (0.64) |
| Qes (measured) | ? (1.24) | 1.21 | ? (1.02) |
| Qms (measured) | ? (2.83) | 3.47 | ? (1.71) |
| Re | 4.6 | 5.9 | 5.2 [?] |
| Efficiency | 92 dB | 92 dB | 90 dB |
| Power Handling | 80W | 75W | 200W |
| Recomended Crossover |
12dB/Oct @ 4k | 12dB/Oct min | ? |
| VC Height | 1.6 mm | 2.2 mm | 2.7 mm [?] |
| Gap Height | 2.0 mm | 3 mm | 2.5 mm [?] |
| Price | $22.95 | $59 | $60 |
Notice the white stuff around the edges of the Focal tweeter. It is from the styrofoam packaging where the surround was touching during transportation. I could find nothing to remove the styrofoam contamination without also harming the foam surround. Needless to say, I was pretty disappointed.