Hi guys,
There has been a lot of discussion on tweeters lately and I thought it might be helpful to look at how some measure, all under anechoic conditions at the NRC. My take is that there are good soft domes, good metal domes, and bad tweeters of all types and materials. It is very hard to generalize. However, there are a few things that should be taken into consideration. First, most designers that actually engineer their own drivers attempt to get pistonic operation within the driver's passband -- they want to avoid any nonlinearities. Basically, they aim for no break-up modes under 20kHz. And in fact they want to push them as far out of the passband as possible (30kHz, 40kHz, beyond). It has been done with a few soft domes, a higher number of exotic hard domes, and some ordinary metals that have advanced dome profiles.
Here is the Vivid G2, aluminum dome with a unique dome profile. Clean operation to 20kHz (refer to listening window):
http://www.soundstagenetwork.com/in...audio-giya-g2-loudspeakers&catid=77&Itemid=18
Here is a Magico V2 with a soft-dome ring-radiator, again with clean response to 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/magico_v2/
Here is a WATT/Puppy 8. You can see the break-up starting at 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/wilson_wattpuppy8/
Focus FS8, with a soft-dome ring radiator, clean to 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/focus_fs8/
Volent VL-2, with a ribbon tweeter, breaking up at 20kHz:
http://www.soundstagenetwork.com/in...ature-edition-loudspeakers&catid=77&Itemid=18
Audio Physic Virgo 25, ceramic-coated aluminum, breaking up at 20kHz:
http://www.soundstagenetwork.com/in...ysic-virgo-25-loudspeakers&catid=77&Itemid=18
The Revel Salon2, with a SOTA Be tweeter, clean to 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/revel_ultima_salon2/
Some of the best speakers I've ever had here used soft domes -- the original Rockport Arrakis and Altair, which both used the Scan-Speak D30. Rockport has since moved on to what they claim performs better -- the S-S Be unit so popular today. The Magico Q7 also uses a Be unit with the same dome profile but different motor and voice coil. These are currently the state of the art in terms of pistonic operation, perhaps with the Accuton Diamond tweeter added in the discussion and Vivid's tweeter, too.
The point here is that great soft domes exist and SOTA hard domes are growing in number. But poor-performing soft domes are around and totally terrible metal domes can be found in many speakers. So, IMO, the generalizing is misleading. You really need to see some good anechoic measurements to know for sure what's going on. As others have said, the implementation is likely more important than the driver material, but SOTA sound comes from great drivers completely optimized in all facets of the design.
There has been a lot of discussion on tweeters lately and I thought it might be helpful to look at how some measure, all under anechoic conditions at the NRC. My take is that there are good soft domes, good metal domes, and bad tweeters of all types and materials. It is very hard to generalize. However, there are a few things that should be taken into consideration. First, most designers that actually engineer their own drivers attempt to get pistonic operation within the driver's passband -- they want to avoid any nonlinearities. Basically, they aim for no break-up modes under 20kHz. And in fact they want to push them as far out of the passband as possible (30kHz, 40kHz, beyond). It has been done with a few soft domes, a higher number of exotic hard domes, and some ordinary metals that have advanced dome profiles.
Here is the Vivid G2, aluminum dome with a unique dome profile. Clean operation to 20kHz (refer to listening window):
http://www.soundstagenetwork.com/in...audio-giya-g2-loudspeakers&catid=77&Itemid=18
Here is a Magico V2 with a soft-dome ring-radiator, again with clean response to 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/magico_v2/
Here is a WATT/Puppy 8. You can see the break-up starting at 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/wilson_wattpuppy8/
Focus FS8, with a soft-dome ring radiator, clean to 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/focus_fs8/
Volent VL-2, with a ribbon tweeter, breaking up at 20kHz:
http://www.soundstagenetwork.com/in...ature-edition-loudspeakers&catid=77&Itemid=18
Audio Physic Virgo 25, ceramic-coated aluminum, breaking up at 20kHz:
http://www.soundstagenetwork.com/in...ysic-virgo-25-loudspeakers&catid=77&Itemid=18
The Revel Salon2, with a SOTA Be tweeter, clean to 20kHz:
http://www.soundstagenetwork.com/measurements/speakers/revel_ultima_salon2/
Some of the best speakers I've ever had here used soft domes -- the original Rockport Arrakis and Altair, which both used the Scan-Speak D30. Rockport has since moved on to what they claim performs better -- the S-S Be unit so popular today. The Magico Q7 also uses a Be unit with the same dome profile but different motor and voice coil. These are currently the state of the art in terms of pistonic operation, perhaps with the Accuton Diamond tweeter added in the discussion and Vivid's tweeter, too.
The point here is that great soft domes exist and SOTA hard domes are growing in number. But poor-performing soft domes are around and totally terrible metal domes can be found in many speakers. So, IMO, the generalizing is misleading. You really need to see some good anechoic measurements to know for sure what's going on. As others have said, the implementation is likely more important than the driver material, but SOTA sound comes from great drivers completely optimized in all facets of the design.