I love electrostatics and this graphene would be great there if they can excite it the way they excite gold plated Mylar. It would be thinner so transients would be really quicker. I just got a new set a year ago. If this replaces Mylar I hope my guy can retrofit what I have.
Cone excursion another for dynamic speakers
Wouldn't mind graphene diaphragm on my Quad 63 s
Roger, my thinking exactly. However, a little poking around revealed that a two inch piece is the biggest they have yet built. No doubt this will be overcome and sheets will be being made just as carbon fiber became mass produced. This could be perfect for electrostatics and other planar speakers.
Well, 300 times stronger than steel, one atom thick, a molecular structure like chicken wire. It has almost zero mass. It presents interesting possibilities for diaphragms, in speakers, microphones and headphones. It already shows great promise in reducing the cost of desalinization of sea water. There is only one layer needed to separate sea water from water. This reduces pressure used greatly which reduces required energy.
I will be interested to see what happens with it in audio.
Last edited by boojum; 16th March 2013 at 10:17 AM..
I wrote the fellow who builds my electostatics. He had this simple example of strength: "It has been calculated that a one-square meter of graphene "paper" (2D configuration) put into a hammock form would support a large cat but weigh less than one of its whiskers."
He also said it is doubtful now that it could replace Mylar. His Mylar sheets are already thinner than the optimum and way thicker than graphene. I will see if he will allow me to quote his in-depth note on the subject. He also said numerous customers had written him and that he had also been following graphene for some time.
Dr. Roger West, co-creator of the electrostatics of SoundLabs, has consented to allow me to include his comments on graphene. It gets into some real techy talk:
"I, too, have been watching the development of graphene for use as a possible membrane in electrostatic speakers. There are still some areas that concern me.
Recently, I've had several customers inquire if I'm going to be using it on our panels. I've been aware of the material for a while but it's obvious that a marketing push is starting up, probably an exercise to find investors. it would be nice to get a piece of it to check out its properties. There appears to be a number of unique applications for the material. The question arises as to whether or not it would be beneficial for use in electrostatic speaker panels as a replacement for the current Mylar film.
Questions arise in my mind like how does graphene behave with adhesives, if its tensile strength is sufficient (no doubt but I'd like to try it anyway), what ultra-violet radiation (ie: sunlight) would do to it, how it reacts to constant corona discharge, if it fatigues with continual bending, what is its thermal expansion characteristic, is it chemically active, etc. Right up front it appears to have too low of a resistivity for use in large electrostatic speakers since the charge on the membrane of a speaker needs to have a very slow migration rate compared to the period of the lowest frequency of interest in order to function as a "fixed-charge" topology. Otherwise, the performance of the panel is adversely affected. The migration rate depends on the resistance/capacitance time constant being high enough (the resistance is that of the membrane and the capacitance is the distributed capacitance of the panel). Graphene, I surmise, has a very low resistivity which might be OK for cell phones and other devices where low frequencies are not important. Another concern is the cost of graphene. I don't think it will be cheap. Just a few years ago graphene was registered as the most expensive material on planet earth (Wikipedia). Also, can it (or will it) be fabricated into the large areas required for a large-scale speaker panel?
The extremely low mass of a film that's only one atom thick is amazing. However, there's a point with speaker design where going lower than a given mass is of no advantage. The mass of the mylar film we use is already below this point and for this reason graphene would not be of advantage. Graphene's strength is not a problem. It has been calculated that a one-square meter of graphene "paper" (2D configuration) put into a hammock form would support a large cat but weigh less than one of its whiskers.
Furthermore, a piece of Mylar that's been coated with the optimum resistivity costs a few cents per square foot. At this point in time graphene probably would cost several hundred dollars per square foot. If the cost of graphene drops to where it is competitive with Mylar and if its reaction to environmental factors is as good as Mylar and if it can be doped in a manner to provide the proper resistivity, then it might be worth considering its use as a speaker membane. Until these questions are answered I don't think it's wise to rock the boat. I feel that at this point it's premature to consider it as a suitable material for speaker membranes."
Like good Dr. West explained, there is much more to a good speaker cone material than weight, strength and stiffness. Firstly, certain weight is needed depending on the frequency range, often bass cones are weighted more to lower the resonant frequency. What good would it do to have hugely expensive and practically weightless material and then have to add lead to arrive to the required acoustic result? Another thing is stiffness, many midrange drivers rely on relatively soft plastics so that the higher frequencies are killed before reaching the edge of the cone, this keeps the radiation angle constant. Having very stiff material would NOT work as well. Strength understood in the conventional matter does not really matter much, relatively weak paper is still one of the best materials for bass/midrange cones. Where lightness and stiffness is most needed is in tweeters and microphones, but even there we now reach past the audible range with the materials available right now. It is nice to have new materials, but I doubt that graphene is going to make any major impact like polypropylene did 30 years ago, or the invention of mid & high frequency domes, or waveguides.