Hi, I'm looking for drivers in the neighborhood of 12-15" made of some kind of rigid material, like carbon fiber, or something like that. Most I've seen are made from treated paper, or something similar. Thanks.
There's a reason for that. A rigid diaphragm of that size will have break-up modes that produce more SPL than the desired response. Some commercially available drivers with rigid cones have break-up mode resonances >20dB louder than the passband response, making them very difficult to use.
What about using six smaller drivers in a circle ( with a natural roll off around 5,000 Hz, with a smaller driver in the centre with a strong output up to 20,000 Hz ?
One of my brief visits (time, job applications, court-case [taking somebody to for not paying me], increasing ennui etc.)
There aren't any current production 12in - 15in wideband drivers using rigid cone materials that I know about. As size increases some form of progressive decoupling of the cone is necessary, and that is usually more practical with materials that are inherently better damped and / or can be molded / pressed into complex forms, varying thicknesses etc. Reinforced paper variations or some form of polymer are therefore generally the preferred option. It's not impossible with rigid or semi-rigid materials -alloys, carbon, kevlar etc., especially with some of the more complex decoupling methods, but cost is likely to be high if reasonable performance is to be obtained.
There aren't any current production 12in - 15in wideband drivers using rigid cone materials that I know about. As size increases some form of progressive decoupling of the cone is necessary, and that is usually more practical with materials that are inherently better damped and / or can be molded / pressed into complex forms, varying thicknesses etc. Reinforced paper variations or some form of polymer are therefore generally the preferred option. It's not impossible with rigid or semi-rigid materials -alloys, carbon, kevlar etc., especially with some of the more complex decoupling methods, but cost is likely to be high if reasonable performance is to be obtained.
If you wanted a "cost no object" speaker, you could use LOADS of the ceramic drivers ( about 1" dia ) out of mini x speakers, about 144 drivers in total would do. One problem ( apart from cone brake up ) would be beaming.