Speaker III – The Tweeters

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 Vifa_D27SG-05 Morel_DMS30-S Focal_TC90KB
Material Silk Kevlar Textile
Faceplate Plastic Plastic Metal
Ferrofluid Yes No Yes [?]
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
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.