There has always been an ongoing debate about the sonic characteristics of tweeter dome materials. Do metal dome tweeters really sound “harsh,” as some claim? Do silk domes sound, well, “soft” or “silky”?
Different materials do have different physical properties as it relates to diaphragm performance and these can and do influence the audible behavior of the driver. With full knowledge that many well-respected designers and engineers have opposing views and opinions on the subject, there are a few basic generalizations that can be made about different tweeter dome materials. We discuss these points in our recent YouTube Video below.
Soft vs Hard Dome Tweeters Comparison: Which one is better?
Metal dome tweeters are generally constructed of alloys of either beryllium, aluminum or titanium. (All of which are chosen for their high stiffness to mass ratio.) They tend to have larger amplitude high frequency break-up modes than soft domes. Softer domes tend to have more break up modes which occur at lower frequencies than metal domes. When a metal dome breaks up, it does so much more dramatically than do soft dome tweeters which have the advantage of having more compliance and damping distributed throughout the dome. The more severe break up modes involve a much higher percentage of the tweeters surface area than a soft dome which tends to do a better job of localizing the disturbance, and isolating the other areas of the surface from the break up. The more dramatic metal dome break ups often will show up as a large dip and/or a narrow spike in the upper end frequency-response. There may be one or several peaks and dips which may be minimized by octave or fractional octave SPL averaging common to PC based measurement programs. Silk-dome tweeters tend to break up more often, but more gently. Some audiophiles feel that makes them more pleasing to the ear even when the break up mode is lower in the audio band than modes commonly seen in metal dome diaphragms.
The metal dome breakup manifests itself in the frequency response curve as a sharp peak, or a sharp dip in its usable frequency range. You can see a prime example of this in a recently reviewed Infinity speaker by Sound and Vision Magazine. Notice the frequency peaking of +10dB out to 20kHz. Some folks may perceive this as detailed or airy while others with more sensitive hearing may find the speaker to sound harsh, especially at loud listening levels where the tweeter can get overdriven.
Full story here from Audioholics — Fabric vs Metal Dome Tweeters: Which is Better?