Driver material = Qualities?

None. It's not so much what you make it out of as how you make it. There are some advantages to specific materials for specific applications, but you can't make any broad generalization as to how a driver will sound based on the cone material.

Most high end drivers use paper. There's also the notion that metal diaphragms produce a metallic sound. That may be so... if you hit them with a stick; otherwise it's just not true. Most of the comments you see about the properties of different cone materials come from those with limited, if any, understanding of how drivers actually work.

There are definitely audible differences between certain cone materials, how audible they are in a specific speaker are completely dependant on the xover design. Stiff cone materials like aluminium have massive breakups, and materials like Kevlar, graphite and magnesium can have pretty large break ups as well. When you hear about a speaker being described as detailed but fatiguing or grating it is often because these breakups are not properly removed. Most cheap metal coned, or "minimalist" designed speakers with stiff cones will have these issues.

You could also say that all tires are made of rubber, too. But there are 1000 different formulations of rubber, plus different configurations and types of reinforcing materials.

It's the same with "paper' drivers. There are all sorts of different fibers that can be used to make "paper" drivers, different ways to orient the grain and length of the fibers, and most of all there are hundreds of different types of resins and coatings to treat the "paper". In general, the engineers are all after the most rigid cone possible with minimum mass, so that the motion of the cone is "pistonic' with minimal flexing due to air resistance.

The "paper" in modern cones has little resemblance to the paper that was used in cones 40 years ago.

Some high-end manufacturers are actually machining cones out of solid blocks of aluminum or magnesium. These solid metal cones are very rigid and strong and approach ideal pistonic behavior.

The Gallo Acoustics Classico series uses a carbon-fiber composite cone, which is expensive but offers excellent rigidity with very low mass. In a sense, you could almost classify it as a type of "paper', but using carbon fiber rather than wood fiber.



Edited by commsysman - 8/3/12 at 2:57pm