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

polytechnique-insights.com

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

#21

Post by _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

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

#22

Post by bob1029 »

buildbot wrote: post #7
jeffbee wrote: post #5

Earlier quoted context omitted.

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.

These seen smaller than a billboard: https://www.crutchfield.com/S-Me16Db11xTX/p_839EMESLD/Martin... And with lower frequency sound, aren't heavy drivers actually better? You literally need more mass/energy to push more air, but at a lot lower frequency so the effect of moving the mass back and forth at 20Hz does not really matter as much as 40Khz?

The weight of the driver is not really a factor so much as a side effect of the engineering. You want to look at it in terms of total volume displaced and the sensitivity (if you are thinking about efficiency). Drivers with more surface area & excursion typically do have larger magnets and support structures.

LFE reproduction is all about moving large volumes of air by any means necessary. There are relatively featherweight subwoofers that literally use fans to move volumes of air and achieve performance that is impossible in traditional drivers of any weight class.

Doesn't really matter how you do it as long as things stay in phase.

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

#24

Post by ahahahahah »

buildbot wrote: post #4
dsr_ wrote: post #2

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

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)

This is the response of someone who knows that electrostatic speakers are a thing and has seen marketing or other images of them, but has no idea how they work and lacks either the curiosity or the capability to learn. The speakers described in this article are nothing close to electrostatic speakers.

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

#25

Post by chrisdhoover »

dist-epoch wrote: post #10
dsr_ wrote: post #2

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

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.

Magnepan speakers have been around since the 1970s. They do not have anything heavy. Martin Logan speakers do have a heavy base presumably the driver.

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

#27

Post by hristov »

dsr_ wrote: post #2

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

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.

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

#28

Post by jakedata »

chrisdhoover wrote: post #25
dist-epoch wrote: post #10

Earlier quoted context omitted.

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.

Magnepan speakers have been around since the 1970s. They do not have anything heavy. Martin Logan speakers do have a heavy base presumably the driver.

Don't confuse magneplanar speakers with electrostatic speakers. Other than them both being flat they are quite different beasts.

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

#29

Post by kennywinker »

KennyBlanken wrote: post #19
smnscu wrote: post #14

[flagged]

> 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.

Just to +1 this, in general nobody wants to read AI textspam anywhere. I hope the trend is over now but like a month ago any time somebody would ask a question on the slack I'm on, someone else would copy-paste 500 words of chatgpt blathering with a similar "disclaimer".

We all know about chatgpt now. If someone wants a chatgpt answer to their questions, they can go get that themselves.

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