Quote:
4 criteria of diaphragm quality?
Hardness (harder is better)
Flexibility (more is better)
Weight (light is better)
...?
And TI figure out which is which.
Regardless... a car may have a V12 engine, but the outcome, how fast the car does a quarter mile or 0-60 is what matters.
Actually, I have a book ( "
High Performance Loudspeakers" by Martin Colloms) which goes into this. It actually has a table that lists the material properties of a whole number of materials suitable for driver diaphragms, including Bextrane, Beryllium, Boron, Carbon fibre composite, Copper, Diamond, Magnesium, Wood, etc.
The science of it all is way over my head, but it specifically notes that:
While some degree of internal damping is desirable in a material or construction, if the loss is too high compared with the E value or stiffness factor the diaphragm might present a smooth frequency characteristic but show increased distortion. An additional effect with high-loss materials, hard to quantify, is a hysteresis phenomenon which subjectively appears to mask fine musical detail...
The values in [the table] can only be a guide since they refer to the properties in sheet form. When made up into practical diaphragm shapes additional factors play their part, such as geometry and self-damping, and the resulting performance cannot be fully determined from the material properties alone.
I wish I could scan this stuff in but sadly can't get my scanner working atm, may try again later. But it lists the relevant figures as: Density (p), Young modolus (E), Specific modulus (E/p), Sonic Velocity ( Square root. (E/P), and the all important Q).
So essentially what it seems to suggest is that its a huge variety of factors and science that is far beyond what is actually provided in marketing materials. It repeatedly cites different manufacturers, particularly KEF's research in these fields. And this is just in regards to the material of the diaphragm - not the cone shape, voice coil, suspension, magnet, enclosure material, standing waves, diffraction due to enclosure shape, psychoacoustics, etc!
I don't know how this scales down to headphones but I'd imagine much the same, though probably they can experiment with more exotic materials / have greater challenges of miniaturisation.
If anyone is interested they perhaps might like to get a copy of the book
