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The SR-009 is made of 3 layers that are "fused" together under high temperature and pressure. The main perforated surface is thin but it is stiffened by ribs that are significantly thicker. It's interesting to note though that you then get less viscous damping from the perforations so this can cause an issue with too little damping from the diaphragm (thin air layer damping is critical in this application because mylar resonances in the mid/highs are not particularly pleasant to hear I believe
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I'm slightly confused by this reply. Do you mean that a thinner perforated surface provides less 'resistance'
(not sure what the correct term would be) to the flow of air, thus reducing acoustic damping on the diaphragm, leading to an underdamped diaphragm with harsh high frequency resonance? That's what I think you're saying, correct me if I'm wrong.
Given that the SR-009 uses
(at least this is what I took from your comment, once again correct me if I'm wrong) standard PCBs that are fused, the use of a material such as corundum may be senseless overkill. However, I still think that for small scale production, where quality over all else is most important, that using different materials would at least be worth some experimentation.
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PCB's are usually made with glass-reinforced epoxy laminate sheets, also known as FR-4, which seems to have reasonable strength. Wachara or Spritzer can confirm that, but I think one of them once posted that SR-007 stator is also an etched PCB.
Although we can find non-metallic materials with better strength (glass, diamond, graphene...), it seems to me that they are still not very suitable when we want to mass produce an electrostatic stator.
Pure metal (titanium) or metal alloys (for instance maraging steel, CO-CR etc) vary in strength and production process. I for one would love to know which metal alloy is used in the SR-009 stator. The metal alloy Stax uses might be suitable for mass production, but unless someone show up with a "poor man" process, they are not very suitable for DIY.
For that purpose (DIY), FR-4 PCB's seem to be the most convenient material available (which does not mean the best material available…).
Thanks for the info on PCBs. Just a side note, the strength isn't all that important, it's the rigidity that counts here. tht's assuming I understand the issue correctly.
What I'm thinking about is a pipe dream of what would be the best possible. When I find something new that interests me I almost always think immediately of what ridiculous ways it could be improved. For instance, when I first saw a carbon fibre dynamic driver I thought about doing the same with a tri-axial CNT weave, something that would be hideously expensive if even possible with todays technology.
So, while PCBs seem to be very good when properly implemented it's still possible that there is something better. I might not be easy for either mass production or DIY, but I'm just thinking out loud here. I find that thinking out loud means that you only have to come up with half an idea - others who are more experienced, knoledgable, or who are just thinking the right way at the time are able to either finish off the idea into something useful, or explain why it's stupid before too much time is wasted on it.
I freely admit that I likely don't know enough about electrostatic drivers to contribute anything that is of significant help, which is why I have thus far read and learned, rather than posted and cluttered, on this thread. I simply saw a number of posts discussing how stator flexion caused distortion and added my $0.02.
Throwing out another off the cuff idea, if a pure metal stator will work (ie one that is conductive in it's entirety rather than just a film on the surface) than BeCu would have the right mix of mecanical and electrical properties for the job. Again, it's expensive and difficult to source and difficult to work with. just a thought.
