Axiom Home Page Forums General Discussion Technical Questions How to fix inverted cones

Hello. I discovered that my kids "somehow" poked in the center bulbs of the speaker cones on my M80 v2. I am not sure of the correct terminology. I am referring to the soft black rubberish dome in the center of the speaker cone. How significant is this? Any way to pop them back out?

Probably not that important to sound quality.

I used a vacuum cleaner - very gently, slowly moving it closer to the dome until it popped back out.

Could suck it out altogether, I suppose. That would be bad.

The v2 dustcap is fabric. An inverted dustcap doesn't affect functionality or performance. Poke a pin in to pull and uninvert.

BTW, v4 dustcaps are white aluminum.

I try to avoid puncturing any part of my speakers.

The v.4 tweeters are protected by a steel or iron mesh grill that's held in place by the tweeter's magnet.

Interestingly, the grills have a hexagonal-patterned mylar layer. I assume it's there to aid in the family of curves.

BTW, a pushed in tweeter is wrecked and needs to be replaced.

Above about 3300 Hz for that tweeter, the dome no longer behaves as a single radiator. Rather, as the frequency increases, so do the number of virtual radiators on the dome. The air pressure waves in front of the dome add constructively and destructively and make a mess of the radiation pattern.

The mesh grill and the hexagonal mylar form an acoustic lens which is used to shape the air pressure delivered into the room. The mylar (phase plug) is specifically used to boost a pressure null towards the higher end of this tweeter.

The phase plug prior to v4 was integrated into the tweeter housing in the form of a piece of black plastic. It had a round circumference instead of hexagonal. So why mylar now instead of it being integrated into the mesh as a single piece? I think by separating into two pieces, it gave Andrew more design flexibility. He could experiment with the shape of the phase plug using an inexpensive material to optimize the shape of the null and the diffraction pattern off the phase plug circumference.

BTW, I'd love to hear the story of the Axiom tweeter struggle from the ti days to the v4. I'd love to know all the grimy details...heh heh...