Graphene Headphones

[Emooze]

A friend alerted me to this and I didn't see it posted anywhere else:

 

http://gizmodo.com/5990520/scientists-have-made-graphene-earphones-and-theyre-amazing

 

I'm not really surprised that a membrane that thin yet strong can produce good sound. But I am excited to see who adopts this tech first and what sort of amp is required to drive them.

[aardvark baguette]

this stuff is supposed to replace silver too, iirc.  

cool

[acidbasement]

Neat.  I wonder about the potential for microphone diaphragms as well.

[guzziguy]

Drum heads?

[Tachikoma]

Its in principle an electrostatic, isn't it?

[spritzer]

A thin sheet of graphene is highly conductive so it wouldn't work as an electrostatic.  Plenty of other ways to do it though. 

[oogabooga]

Actually, it is electrostatic. Here's the abstract of the original journal article:

"Graphene has extremely low mass density and high mechanical strength, key qualities

for efficient wide-frequency-response electrostatic audio speaker design. Low mass

ensures good high frequency response, while high strength allows for relatively large

free-standing diaphragms necessary for effective low frequency response. Here we report

on construction and testing of a miniaturized graphene-based electrostatic audio

transducer. The speaker/earphone is straightforward in design and operation and has

excellent frequency response across the entire audio frequency range (20HZ – 20kHz),

with performance matching or surpassing commercially available audio earphones."

Bias voltage appears to be a paltry 100V.

http://arxiv.org/pdf/1303.2391v1.pdf

Edited March 16, 2013 by oogabooga

[spritzer]

Going by the document they didn't measure distortion at all.  That's where constant current ESL's come into their own, something you can't really do with a highly conductive diaphragm.  Now if they took the Final Audio root and biased the stators and put the signal on the diaphragm... 

[complin]

Well there is this new Fuji material released recently also.  Initially aimed at speakers but would have thought possible uses in headphones too.#

Fujifilm Unveils Bendable, Foldable, Roll-up Speakers

Feb 1, 2013 10:47Motonobu Kawai, Nikkei Electronics

A retractable speaker

Fujifilm showed speakers of various shapes

Fujifilm Corp developed a film that can be use as the diaphragm (vibrating plate) of a speaker and unveiled it at nano tech 2013, a trade show that runs from Jan 30 to Feb 1, 2013, in Tokyo.

By using the diaphragm, which Fujifilm calls "Beat," it becomes possible to realize a speaker that can be bent and folded. At the trade show, the company exhibited a slim speaker, retractable speaker and Japanese fan (sensu)-like speaker.

To realize a bendable diaphragm, a soft material is required. However, because soft materials absorb vibration, it is difficult to ensure a flexibility and high acoustic characteristics at the same time. This time, Fujifilm ensured both of them by using a viscoelastic polymer that hardens in the audible range (20Hz to 20kHz) and softens in the range for bending it by hand (several hertz).

Fujifilm mixed the viscoelastic polymer with piezoelectric ceramics to make a piezoelectric composite and packaged it with a protection layer after sandwiching it with electrodes. When a voltage is applied to the electrodes, the piezoelectric ceramics vibrates, and the viscoelastic polymer functions as a diaphragm.

The strain energy generated by bending the film by hand is released as heat, preventing cracks, peel-off, etc. In the audible range, the film keeps an internal loss appropriate for a diaphragm. The viscoelastic polymer was developed based on materials that Fujifilm developed in the past

Edited March 16, 2013 by complin

[complin]

The graphene material looks really exciting, something that Stax ought to be evaluating?

[Tachikoma]

If they had the budget for a $100K headphone, sure.

[morphsci]

The cost of graphene should be dropping shortly. It has lots of extremely lucrative uses outside of audio.

[complin]

I thought that was going to be the price of the new Stax SR-010 with amplifier anyway 

 

If they had the budget for a $100K headphone, sure.

[Pirx]

A thin sheet of graphene is highly conductive so it wouldn't work as an electrostatic.  Plenty of other ways to do it though. 

What about case when you charge stators coated with something high conductive and signal is put to graphene diaphragm? This could work, I think.

[spritzer]

Not on a constant charge basis. 

[Emooze]

That paper is terribly written but they describe another project, the "thermoacoustic" loudspeaker:

 

"In the thermoacoustic configuration graphene serves as a stationary heater to alternately heat the surrounding air thereby producing , via thermal expansion, a time-dependent pressure variation, i.e. sound wave."

[swt61]

^

 

You mean there are still some of you that haven't turned your toasters into speakers yet? 

[spritzer]

Nice twist on the plasma concept but as with so many of these things, it has limitations. 

 

I for one remain skeptical that thinner diaphragms are necessarily better for electrostatics.  The weight of the air the diaphragm is asked to excite is an issue as is the stability of the material and its damping properties.  Now if we could get a material that is stronger than mylar at any given thickness and provides better damping then we'd have something great. 

[Tyll Hertsens]

Seems to me, given the size of the driver, that this tech is more appropriate for in-ear and on-ear cans.

 

I don't know how big this driver can get given that it looks like it's built sort of like a chip.

 

Am I missing something?

[spritzer]

Graphene is strong but size would be an issue for a large (50mm or larger) driver. 

[mypasswordis]

http://www.gizmodo.co.uk/2013/03/making-salt-water-drinkable-just-got-99-percent-cheaper/

 

1000 times stronger than steel by weight doesn't seem so bad. Not sure how accurate the article is, so I went on wikipedia (a clearly much more credible source) and found this: As of 2009, graphene appears to be one of the strongest materials ever tested. Measurements have shown that graphene has a breaking strength over 100 times greater than a hypothetical steel film of the same (incredibly thin) thickness,^[145] with a tensile modulus (stiffness) of 1 TPa (150,000,000 psi).

 

BoPET wiki article says it's approximately 4 GPa.

 

Edit: Original headphone article also says 100 times stronger, not 1000.

Edited March 18, 2013 by mypasswordis