I'm a big fan of composites, and I think that ribbon tweeters have potential too.
One problem that I've had with ribbons is blowing up diaphragms.
Graphene is an interesting solution. At the molecular level it's a honeycomb structure, and it's incredibly thin. These two properties are ideal for a loudspeaker; light and strong are what you want for a driver.
I cannot find a way to purchase graphene online, but it appears that it should be possible to make ribbon diaphragms at home. Here is how you can do it.
1) buy a lightscribe CD rom drive. I had one of these about a decade ago. It was a short lived technology that allows you to 'burn' designs into a CD ROM.
2) Follow the instructions available online, to 'grow' a layer of graphene using the laser on the CD burner:
Boffins use DVD burner to scale graphene supercapacitors ? The Register
3) The last step is to simply bond the graphene to your ribbon diaphragm. For instance, if you are using a ribbon tweeter, you would bond the graphene to the aluminum ribbon. There are a number of articles on making your own ribbon diaphragm; here is one:
http://www.troelsgravesen.dk/download/JP3 Ribbon Replacement.pdf
Graphene is conductive, so it might even be plausible to just use a 100% graphene diaphragm. That's right, a loudspeaker diaphragm that's one atom thick!
One problem that I've had with ribbons is blowing up diaphragms.
Graphene is an interesting solution. At the molecular level it's a honeycomb structure, and it's incredibly thin. These two properties are ideal for a loudspeaker; light and strong are what you want for a driver.
I cannot find a way to purchase graphene online, but it appears that it should be possible to make ribbon diaphragms at home. Here is how you can do it.
1) buy a lightscribe CD rom drive. I had one of these about a decade ago. It was a short lived technology that allows you to 'burn' designs into a CD ROM.
An externally hosted image should be here but it was not working when we last tested it.
2) Follow the instructions available online, to 'grow' a layer of graphene using the laser on the CD burner:
Boffins use DVD burner to scale graphene supercapacitors ? The Register
3) The last step is to simply bond the graphene to your ribbon diaphragm. For instance, if you are using a ribbon tweeter, you would bond the graphene to the aluminum ribbon. There are a number of articles on making your own ribbon diaphragm; here is one:
http://www.troelsgravesen.dk/download/JP3 Ribbon Replacement.pdf
Graphene is conductive, so it might even be plausible to just use a 100% graphene diaphragm. That's right, a loudspeaker diaphragm that's one atom thick!
Here's a loudspeaker that Berkeley made with the material:
Berkeley creates the first graphene earphones, and (unsurprisingly) they’re awesome | ExtremeTech
Here's the response of the graphene diaphragm versus a conventional diaphragm. Note the lack of a high frequency peak, likely due to the very low weight and the honeycomb structure of the material.
Berkeley creates the first graphene earphones, and (unsurprisingly) they’re awesome | ExtremeTech
Here's the response of the graphene diaphragm versus a conventional diaphragm. Note the lack of a high frequency peak, likely due to the very low weight and the honeycomb structure of the material.
Nice, I was looking for a measurement of that speaker yesterday and couldn't find it. Really not a great looking graph, but that doesn't mean it couldn't be. Lightscribe was not a short lived technology, btw - they still make them.
Anyhoo, 100% graphene is the whole point, right? I have a hard time believing anybody could get really get a good piece of it made at home like that, but it is pretty tempting to give it a try. On the other hand, I'm not very keen on trying to make graphite oxide myself. Wonder how much it costs...
Anyhoo, 100% graphene is the whole point, right? I have a hard time believing anybody could get really get a good piece of it made at home like that, but it is pretty tempting to give it a try. On the other hand, I'm not very keen on trying to make graphite oxide myself. Wonder how much it costs...
Are you the patrick bateman of tic tac toe? Interesting idea to use graphene on ribbons. I wander if you could build electrostats from graphene as well? Surely in theory.
I know this is going to sound semi-absurd, but I wonder if it would be possible to make a graphene/aluminum/graphene CLD diaphragm using scotch tape and a #2 pencil?
Basically it would go like this:
1) Get a compression driver with an aluminum diaphragm. I have some JBL 2470s here with Radian diaphragms.
2) Cover both sides of the diaphragm with graphite. Just cover it with a #2 pencil.
3) Reduce the graphite to graphene using scotch tape.
The whole idea of CLD is to have a hard layer, then a soft layer, then a hard layer. And graphene composites work best in very low volumes. Here's a quote:
"At this point, we shouldn’t be wholly surprised that graphene — which holds a huge number of superlative titles, including the strongest material known to man — can also be used to create strong composite materials. In this case, the KAIST researchers created a copper-graphene composite that has 500 times the tensile strength of copper (1.5 gigapascals), and a nickel-grapehene composite that has 180 times the tensile strength of nickel (4 gigapascals). This is still some way off graphene’s tensile strength of 130 GPa — which is about 200 times stronger than steel (600 MPa) — but it’s still very, very strong. At 1.5 GPa, copper-graphene is about 50% stronger than titanium, or about three times as strong as structural aluminium alloys.
I know that the idea of making a CLD with a #2 pencil seems a little absurd. Then again, when you see a tweeter with "vapor deposited aluminum" in the description, all they're doing is spray painting it.
Here's how to make graphene with scotch tape and a pencil:
BBC News - How sticky tape trick led to Nobel Prize
Basically it would go like this:
1) Get a compression driver with an aluminum diaphragm. I have some JBL 2470s here with Radian diaphragms.
2) Cover both sides of the diaphragm with graphite. Just cover it with a #2 pencil.
3) Reduce the graphite to graphene using scotch tape.
The whole idea of CLD is to have a hard layer, then a soft layer, then a hard layer. And graphene composites work best in very low volumes. Here's a quote:
"At this point, we shouldn’t be wholly surprised that graphene — which holds a huge number of superlative titles, including the strongest material known to man — can also be used to create strong composite materials. In this case, the KAIST researchers created a copper-graphene composite that has 500 times the tensile strength of copper (1.5 gigapascals), and a nickel-grapehene composite that has 180 times the tensile strength of nickel (4 gigapascals). This is still some way off graphene’s tensile strength of 130 GPa — which is about 200 times stronger than steel (600 MPa) — but it’s still very, very strong. At 1.5 GPa, copper-graphene is about 50% stronger than titanium, or about three times as strong as structural aluminium alloys.
I know that the idea of making a CLD with a #2 pencil seems a little absurd. Then again, when you see a tweeter with "vapor deposited aluminum" in the description, all they're doing is spray painting it.
Here's how to make graphene with scotch tape and a pencil:
BBC News - How sticky tape trick led to Nobel Prize
The thing about the tape is how small the flakes are (microscopic). You need a large continuous crystalline structure, I think. Otherwise it's just a bunch of graphite stuck to the diaphragm.
@lejockey, electrostats are what the link/measurement is.
@lejockey, electrostats are what the link/measurement is.
Note that the graphene diaphragm is some 40 dB down at 16 kHz, utterly lacking in HF response, as well as HF peaks. Also more than 40 dB down at 30 Hz, "balanced" response 😉.
Also note they compared it to one of the worst conventional headphone response one could find.
That's probably not fair, for a bunch of reasons:
- efficiency is very high, so probably overall smoothness is the only important thing, and...
- The tilted response with ripple at the top was measured using the mic of a cheap Sony portable voice recorder and REW. Not exactly shooting for acoustic lab accuracy.
- There is also an LDV measurement (not posted above, see PDF), which looks entirely horrible too, but in an entirely different way, but I'm not sure I know how to interpret it. I'm guessing it would also be very easily influenced by ambient effects (maybe that's the high margins of error in the graph?).
- This is a tiny 7mm diaphragm with electrodes held on by a spring clip, and no claims to have optimized, well... anything about it.
As far as the article in the OP, though, it's true, Sebastian Anthony clearly has no idea what "awesome" driver performance looks like, and the Berkeley paper is pretty generous with terms like "quite flat", too 🙂.
- efficiency is very high, so probably overall smoothness is the only important thing, and...
- The tilted response with ripple at the top was measured using the mic of a cheap Sony portable voice recorder and REW. Not exactly shooting for acoustic lab accuracy.
- There is also an LDV measurement (not posted above, see PDF), which looks entirely horrible too, but in an entirely different way, but I'm not sure I know how to interpret it. I'm guessing it would also be very easily influenced by ambient effects (maybe that's the high margins of error in the graph?).
- This is a tiny 7mm diaphragm with electrodes held on by a spring clip, and no claims to have optimized, well... anything about it.
As far as the article in the OP, though, it's true, Sebastian Anthony clearly has no idea what "awesome" driver performance looks like, and the Berkeley paper is pretty generous with terms like "quite flat", too 🙂.
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