Some of you have experienced issues with low mass tweeter designs.In my decades of research I was always reminded by physical rules.If we respect this we learn to predict which result we will get. From our evolution we react first to a air pressure change, before we hear a tone. We are more sensitive to a first Positive air pressure change. The best possible step response of a speaker system should be a fast positive rise with ana-periodically damping. We want a Q-Factor of around 0.7 over the whole frequence range. The waterfall diagram therefore should show the form of a sickle. If we go away from this ideal, our brain tries to correct the artefacts and causes us to interpret it different, depending on our listening experience, age and actual condition. It becomes subjektive, an indication that it's far from true. In the same way we like a constant relation between the mass of an active part of a diaphagm and the spring rate to return it to it's 0 possition of around, Cms = 0.4mm/N at home SPL and over the whole frequenze range. For any Dome Tweeter with around Mms = 0.4g Diaphragm and a low Fs Resonance of 600 Hz this is fine. In a 2 Way-Speaker this could virtually disapear. If the Tweeter has Fs 1200 Hz instead it will be visible with Cms = 0.1mm/N, if the woofer has Cms 0,4mm/N. A Softdome is more forgiving. If Cms gets very high, often seen with Ribbon Tweeters, it might sound too lean. Between 1kHz and 3kHz our ears are very sensitive to detect resonances and hard phaseshifts. Best regards.
