Classic components could be replaced by rubber in next-gen loudspeakers

[_Microft]

These speakers seem to work like this:

There is a rubber layer, coated with conducting material to serve as electrodes. The signal is applied in form of a high voltage which makes the electrodes attract each other and contract the rubber in between perpendicular to the surface (i.e. the rubber layer gets thinner). Since the rubber material is relatively incompressible though (volume of the material doesn't change), the surface area of the membrane has to increase in return. To generate sound from that, the membrane is stretched over a cavity that is under higher than ambient pressure which helps expand the 'balloon' when its surface area increases. This displaces surrounding air which means the contraption is emitting soundwaves.

(I could only find a thumbnail of the first page of a paper from that professor and extracted this from it)

https://www.aes.org/e-lib/browse.cfm?elib=21108

[yummypaint]

This sounds like an "electroactive polymer." there are some squishy tapes made by 3m that incidentally have this property out of the box. Make a spot of conductive carbon paint on each side, apply a few kV, and watch the spots double in area as the electrostatic forces squish the material.

[nrp]

It sounds a little like Bayer’s ViviTouch, but for higher frequency bands. ViviTouch was only used for haptics and sunwoofers as far as I know. https://www.innovationworldcup.com/finalist/vivitouch-eap-he...

[sublinear]

> Current loudspeakers use a magnet coupled with the movement of a copper coil to vibrate a membrane. In the future these heavy, bulky, and expensive components could be replaced by a dielectric elastomer membrane.

They mention efficiency, but not power. I don't like how this is framed as the general future of all speakers when it's really just the future of midrange drivers.

[teknopaul]

Heavy speakers is a plus when moving low frequencies. Otherwise you have to strap or bolt them down and together.

_Might_ be the future of mids, but I doubt it. Advancement in ribbon speakers is more likely IMHO. Also people develop a taste for how some speakers sound. I don't see guitar music being played on anything too different for a while, unless it has the same sound character. Even if technically it's a better reproduction, it has to reproduce how paper cone speakers sound now better than paper does. Seems unlikely. To win, people have to like the new sound more, or not be able to tell the difference.

[Puts]

Wouldn't rubber dry out over time? If you pay for a good set of speakers you probably want them to last for decades.

[teh_klev]

I have a pair of 35 year old Mission speakers constructed using rubber and so far there's no evidence of degradation and they still sound great.

I imagine if this was a tyre then it wouldn't fare so well because the rubber compound is for a completely different use and also exposed to adversities such as wide temperature differences and all sorts of kinetics that a speaker will never experience (hopefully).

[Nition]

Lots of traditional speakers already use a rubber ring around the edge of the cone.

[coldtea]

Couldn't you just replace it? We also pay for good cars, but we still change their tires every so often...

[runeks]

I find it a bit strange that this article doesn’t mention electrostatic speakers, as the two appear similar.

It would also be worth mentioning if this new tech suffers from the same limitation as electrostatics, namely that the membrane’s range of motion is so small that you need several square meters of membrane to reproduce low frequencies at high volume.

[dsr_]

This appears to be describing an electrostatic speaker. They're on the market, and have been for decades, using mylar or a similar material.

[hristov]

It doesn't. This scheme uses a membrane like the electrostatic speakers, but otherwise it is quite different. In the electrostatic speakers, you load the membrane with extra electrons and then use electro-magnets to apply a varying electric field across the membrane in accordance with your sound signal. Since the membrane has much more electrons than protons, the electric field causes the membrane to move. This method requires magnets.

The system in the article does not use magnets. What they do is they make a membrane that moves when a voltage is applied between its top and bottom surfaces. Thus, the membrane can probably be referred to as being piezoelectric, although the article does not use that term. In this case you can apply the sound signal directly to the membrane and make it move, and when it moves it creates sound. Thus, this system does not require any magnets.

The lack of magnets will make it much lighter. Also, the fact that you are applying the signal directly to the thing making the sound may result in better sound quality.

[dist-epoch]

I'm not so sure. Electrostatic speakers have big heavy metal electrodes.

They talk about a thin conducting layer on the rubber, quite a different thing.

[buildbot]

Yeah I am really nonplussed how this is the top post on HN right now (I know that is against the rules to mention but really)

[vr46]

I was wondering much the same, except I note that my pal’s massive Quads and the older radiator-like versions at uni were still crazy heavy due to the power supply (I assume) and they were a bit short on warm bass, perhaps these “new” speakers run on a trickle of power and produce bass like a Cerwin-Vega for all I know?

[tapper]

My screen readers reads that site in a verry strange way. It says that there is soft hyfens in a lot of the words so it reads the words like repro­duce as"repro duce"

[erik]

It looks like they are doing some sort of dynamic text justification. If I change the text width by resizing the window it dynamically inserts hyphens at line breaks. Presumably via some javascript library.

[gtvwill]

Ehhhh interesting, might go well for tweeters. Can't see it being great for bass. Can't be arranged in a paraflex horn config.

[Kapura]

The article mentions the fragility, but seems extremely optimistic on the ability to solve this, but I'm not sure way. It just says "once this is overcome" but the things it seems to be talking about are major barriers to a commercial product.

[ksec]

It was just the other day I was thinking how big, comparatively speaking the speaker components are in MacBook and iPhone. And if we could somehow make it even smaller without any compromise on quality and longevity.

[buildbot]

This seems only mildly different than already existing electrostatic drivers??? In terms of getting rid of heavy magnets at least.

[jeffbee]

Yes, as we know from the history of electrostatic speakers, all you need to replace those bulky magnets is a sheet of mylar the size of a billboard, and also a regular magnetic voice coil for the half of the power spectrum that they can't handle.

[sandreas]

If you want an affordable, good sounding speaker that you can build yourself, you might wanna take a look at Tech Ingredients:

https://www.youtube.com/watch?v=CKIye4RZ-5k

[KennyBlanken]

> I had ChatGPT expand on the paragraphs

Yeah, don't do that. Nobody wants to read "AI" textspam here in the comments.

> so take the audiophile considerations with a grain of salt lol.

The understatement of the year. Repeat after me: chatgpt is not deterministic.