To Doug Schneider,
I’m shopping for my first pair of speakers and I’m wondering if I should look for a soft- or hard-dome tweeter. Some people tell me that the soft domes sound better. Is this true?
This question comes up every so often because generalizations do get made about the various tweeter diaphragm materials. Soft-dome tweeters are usually made from silk and are said to have a “sweeter” high-frequency sound. That character has a bit to do with the way the silk dome breaks up in the highest frequencies. Hard-dome tweeters usually have a metal-based dome and break up differently. Aluminum, titanium, and beryllium are common materials used today. Many people feel that each of those materials has a characteristic sound, with beryllium usually being described as the smoothest-sounding because its first break-up mode is much higher than the audio band. The problem with beryllium is that it’s very expensive, so you tend to only find it used on pricey speakers. Aluminum and titanium, which are much cheaper, and are used often in lower-priced speakers, show break-up behavior much closer to the audio band, so some people find these to be a touch harsh if the designer hasn’t done anything to tame these resonances. There are other materials as well, even diamond, but there's no need to get into all that here!
Although I’ve found that some of these generalizations about the sound of each material are somewhat true, what’s more important is the overall driver design. For example, one of the best-sounding tweeters I’ve heard is in Vivid Audio’s speakers and it uses an aluminum dome. Their engineers did some clever things to generate the smoothest sound possible from this material. But I’ve also found great-sounding titanium-, beryllium- and silk-dome designs as well. And I’ve heard some bad ones. The key here isn’t to focus on the dome material, but, instead, on the final result. In other words, what it sounds like. The way to test that is, of course, with your ears, so don't discount any speaker you're shopping for just because of what the tweeter is made of. . . . Doug Schneider