More On The Ring Radiator Tweeter
Just like driver cones, tweeter diaphragms are prone to materialresonance that cause frequency response errors and distortion. Careful choice of material is important, as is the geometry of the diaphragm. Tweeter diaphragms must be able to vibrate at least 20,000 times per second! That’s fast, and it stands to reason that light weight is especially important in tweeters. But as we saw earlier, light, well-damped materials are not stiff and even a tweeter needs to be stiff to avoid ”decoupling” and other problems. A dome shape helps give the diaphragm greater structural integrity and stiffness.
Take a look at a cross-section of a typical tweeter dome. You can see that the dome is supported by the voice coil only along its circumference. That means there is a vast area of diaphragm that is not supported, making the tweeter prone to resonance developing in the dome material.The ultra-light, woven diaphragm is supported at two pivot points, with the voice coil attached roughly midpoint between the two pivots. With very small areas of unsupported material, there’s less opportunity for performance-robbing resonance to develop. The integrated phase plug prevents phase cancellations to maintain flat, smooth response both on- and off-axis.