Originally Posted by wuwhere
They probably use copper. The 6 uses gold. There are newer materials that is thinner, lighter and have higher temperature than mylar for diaphragm. They can now bond the traces on the diaphragm without using glue. If only they can find a magnet that is stronger but lighter.
Perhaps he found a manufacturer within China that charges him for less?
Bring down the price and sell more, your revenue would be more overall. Just my opinion.
No, they don't use copper, they use aluminum. Copper has four times the density of aluminum but only 1.5-2 times the conductivity of aluminum - making aluminum the clear choice for the lightest (and most efficient) diaphragms possible. As far as I know, the only etched planar drivers that use anything but aluminum are the new Fostex drivers (which use copper) and the HE-6. Infinity and all the clones of their EMIM/EMIT drivers use aluminum, as well as all of the rest of the Hifiman planar headphones. I don't know why the HE-6 uses gold (given its high density and relatively low conductivity for its density), but it may explain their extreme inefficiency. It may have been a manufacturing advantage in terms of the ease of depositing gold directly on the diaphragm - which Hifiman apparently hadn't mastered yet for aluminum.
Hifiman presumably use a polyimide (i.e. reverse-engineered DuPont Kapton) diaphragm - as you say, thinner, lighter, and more stable over a wide range of temperatures. Magnepan has always used Mylar for their large panels; Infinity pioneered the use of Kapton in their diaphragms. They also deposited the aluminum directly on the Kapton, like Hifiman now does.
I am assuming they're already using Neodymium magnets... There just isn't any stronger permanent magnet. Yet, anyway. Luckily, its patents (as well as Samarium Cobalt magnets) have since expired so they're not as expensive as they used to be. Incidentally, Infinity also pioneered the use of both of these materials in planar speakers as well.
It's really interesting to see how different manufacturers build on top of one another in terms of technology. Rarely (if ever) does anyone come up with a completely revolutionary idea and go all the way to a truly successful product with that idea - most of the time we take baby steps towards realizing it and improving it along the way. Just like the guy who thought of the wheel and its potential probably didn't create the wheelbarrow too...