Cone Material

[DanielT]

New material!

"Researchers at MIT have developed a lightweight, paper-thin loudspeaker that can be attached to large surfaces like wallpaper.

Most existing thin-film loudspeakers need to stand up on their own so they can bend and produce sound. "Mounting these loudspeakers onto a surface would impede the vibration and hamper their ability to generate sound," MIT News explains.

With the researchers' new approach, the entire loudspeaker doesn't need to vibrate. Instead, it features "tiny domes on a thin layer of piezoelectric material which each vibrate individually." Space on top and bottom of the domes—"each only a few hair-widths across"—let them vibrate without being damaged."

MIT Researchers Develop Lightweight, Ultra-Thin Loudspeaker Material

The design relies on tiny piezoelectric domes working together.

uk.pcmag.com

 

[Holmz]

…
It is difficult to say which material is better than the other because the midrange crossover design has a very important
effect on the sound quality.

Maybe there is something like Klippel testing for the bare driver without the crossover and the rest of the speaker enclosure?

 

[DanielT]

But do rigid materials prevent (if well constructed, and crossovers are set low enough) membrane distortion effects? Or?

Mode Shape Simulation:

Edit:

I saw the graph on this page:

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danesian.dk

 

[Katji]

Maybe there is something like Klippel testing for the bare driver without the crossover and the rest of the speaker enclosure?

Klippel does that...and it will show the inconsistencies in mass and stiffness resulting from this:

Thank goodness for paper as a cone material.

When I re-foam speakers I will also make a water 80% - glue 20% mixture and

use a brush to cover the cone with it to help stiffen it up.

 

[Katji]

I've seen paper cones in the rear-deck of a car deteriorated from the sun. But I have home speakers with paper cones that are about 40 years old and still OK. I don't know if there is any kind of coating but they just look-like heavy-paper. The midranges have cloth surrounds and the woofers have rubber surround.

The paper is impregnated/doped with something, not visible. ...Probably visible when compared with the untreated paper.

Sure lasts longer in exposure to sunlight than the plastics.

The midranges have cloth surrounds and the woofers have rubber surround. (The tweeters are mylar).

I've seen lots of disintegrated foam surrounds. I don't know what they use for the foam but it's obviously not the same as the (butyl?) rubber used in my woofers.

This type lasts forever, you could say it's more bulletproof than Kevlar* :

 

[sq225917]

Talking about cones in isolation is only a part of the story, motor system, xo and cone termination all play an equally important role. ( or half roll)

 

[KMO]

KEF has been using an aluminium-magnesium alloy for a while now. Nice and rigid in the operating range, but the trick is to stop it breaking up at high frequencies, causing a big spike up where the tweeter should have taken over.

 

[AnalogSteph]

KEF has been using an aluminium-magnesium alloy for a while now. Nice and rigid in the operating range, but the trick is to stop it breaking up at high frequencies, causing a big spike up where the tweeter should have taken over.

That's typically the crux with metal membranes (and domes). Superb stiffness but very little internal damping, hence the big spikes.

You've got to respect how well paper does in the grand scheme of things. Perhaps this should not be overly surprising with it essentially being a composite material to begin with, with a number of things you can soak it in if needed. It also is generally inexpensive and non-toxic.

Should researchers ever end up finding the holy grail of cone material, chances are it'll be some sort of composite job.

 

[KMO]

That's typically the crux with metal membranes (and domes). Superb stiffness but very little internal damping, hence the big spikes.

KEF dealt with the cone's spike with some sort of rubber coupling between the voice coil and the cone - rigid at lower frequencies, then it squishes at higher ones.

The aluminium tweeter dome's spike is still there, but it's pushed to inaudible frequency by their stiffened dome. If you ever see a wide-bandwidth plot, current KEF Uni-Qs have a huge +20dB spike at around 30kHz.

Which is why their specs have responses like:

+/-3dB: 31Hz-24kHz
-6dB: 26Hz-36kHz

The -6dB lets them include the +20dB at 30kHz...

 

[DanielT]

A comparison: SB Acoustics SB17CAC35-4 6 Inch Ceramic Midwoofer vs MONACOR SP-8 / 150PRO with paper cone / diaphragm material.

SB Acoustics SB17CAC35-4 6, with aluminum coated ceramic cone / diaphragm. It's going really well, until it does not. Then it really breaks up. 24 dB filter will probably be needed , crossover to tweeter that is.But good FR and really low distortion.

SB Acoustics SB17CAC35-4 6 Inch Ceramic Midwoofer:

SB Acoustics SB17CAC35-4 6 Inch Ceramic Midwoofer Review

SB Acoustics SB17CAC35-4 6 Inch Ceramic Midwoofer Review

www.erinsaudiocorner.com

Compared to this speaker element, MONACOR SP-8 / 150PRO.
Cone / Diaphragm Material paper (untreated paper, I'm almost sure it is, only paper is mentioned in the datasheet.). FR looks good, fine roll off higher up in frequency, no violent break-up but what about distortion levels? For that speaker element and for speaker elements in generally with
untreated paper in the diaphragm? For speaker elements in paper that is 6.5 inches or larger.

MONACOR SP-8 / 150PRO

MONACOR: Products

Compact PA bass speaker, subwoofer, 150 W, 8 Ω 20 cm (8

www.monacor.com

MONACOR SP-8/150PRO - 8″ Subwoofer

8″ Subwoofer, 56 Hz, 300 W, 91 dB, 8 Ω

www.loudspeakerdatabase.com

 

[ryanosaur]

24 dB filter will probably be needed , crossover to tweeter that is.

Or put a notch filter up there to further attenuate the breakup.

 

[Holmz]

Klippel does that...and it will show the inconsistencies in mass and stiffness resulting from this:
…

So @valerianf can know which material is better?

 

[Slayer]

You've got to respect how well paper does in the grand scheme of things. Perhaps this should not be overly surprising with it essentially being a composite material to begin with, with a number of things you can soak it in if needed. It also is generally inexpensive and non-toxic.

Agreed, with the statement of respecting paper cones. I admit I am biased towards paper. I have tried many different speakers over the years with so called exotic cone materials. Yet I still found myself going back to paper. Totally subjective I know; I just find they seem to have a better clarity than other materials used for cones.
As for inexpensive, guess that would all depend on the mix. Paper, wood and felt mixed cones, can be a more costly and time-consuming process than some other so called exotic materials. If I can find the video on the whole process, production and material breakup comparisons, I will post it later.
Admittedly, at this point speakers have come so far, it would be difficult for one to hear a difference without careful scrutiny and probably long listening sessions with the beast of ears.

 

[Mnyb]

If one is going to be slightly cynical . The cone/dome material matters a lot if wrongly implemented

And also I think speaker manufacturers are guilty of some of the prejudices we have . I remember when metal domes became a thing , they made sure you heard it . If a fancy tweeter is a part of the marketing you sure be hearing it .

Joking aside I think it’s comes down to implementation in the particular design at hand .

And some stubborn designers tries the impossible of very hard cones and first order filters ? You will hear that to

 

[thewas]

If one is going to be slightly cynical . The cone/dome material matters a lot if wrongly implemented

Exactly, had written the same here

The effect of materials employed in drivers re loudspeaker performance

I noticed in one of Amir's speaker reviews a newer member made an allusion to driver materials having some salutary influence on the reproduced sound of a speaker. All things being equal, I wonder how true this assertion really is. I know it's a great marketing point for some of the companies...

www.audiosciencereview.com

 

[bigjacko]

But do rigid materials prevent (if well constructed, and crossovers are set low enough) membrane distortion effects? Or?

Mode Shape Simulation:
View attachment 206202

Edit:

I saw the graph on this page:

View attachment 206203

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Our services We offer a wide variety of services covering areas such as R&D, purchasing, planning, production, QC and project management. With decades of experience in the audio industry, we are equipped to assist you in all aspects of product development and production. Header P1020097...

danesian.dk

Yes, Lars Risbo said the new purifi aluminum woofers has lower distortion due to stiffer cone. Although hard to tell from the graph because the paper version already got very low distortion. Lars also mentioned there is 8 inch aluminum version coming out with 10 db better distortion, which is crazy good improvement.

 

[DanielT]

Yes, Lars Risbo said the new purifi aluminum woofers has lower distortion due to stiffer cone. Although hard to tell from the graph because the paper version already got very low distortion. Lars also mentioned there is 8 inch aluminum version coming out with 10 db better distortion, which is crazy good improvement.

And now we are talking speakers, not, for example, DACs (where most nowadays have completely inaudible distortion).

My guess: Different computer-based programs plus the development of speaker elements, for example different materials in the cone, is the most important thing regarding the development of increasingly better sound.

Sure, then the speaker elements should be implemented in a good way in the speakers, but the potential is there.

 

[bigjacko]

And now we are talking speakers, not, for example, DACs (where most nowadays have completely inaudible distortion).

My guess: Different computer-based programs plus the development of speaker elements, for example different materials in the cone, is the most important thing regarding the development of increasingly better sound.

Sure, then the speaker elements should be implemented in a good way in the speakers, but the potential is there.

I would say better physics model that pridict the reality, simplified but with good assumption. Program with good programming that optimize calculation. FEA model with optimized calculation. In the end physics model and FEA are the only thing you need for knowing driver and design it, but they can range from simple to complex to monsters.

 

[Els]

Davis Acoustics doesn't have a clue how to properly design speakers, no one should care about what material they use, since they do not know what yo make of it.

Paper is probably the most common. Yet, there is no consensus.

Loudspeaker Drivers: Identifying Legitimately High Fidelity Parts

This article focuses attention on loudspeaker drivers defining the basic core elements that make up the drivers & trade offs associated with various design approaches. Better parts MAKE a difference!

www.audioholics.com

What makes you say that? They seem to be very popular in France, it looks like JM Lab and Audio Reference used them in early days.

 

[VintageFlanker]

First, please consider that I'm talking about the actual Davis Acoustics, not when the company was run by Michel Visan several years ago.

They seem to be very popular in France

What of it? Total DAC and Atoll are also "very popular". That doesn't make their products actually good. In addition, by 2022, Davis is only "popular" in the entry level range, that you can find in big chains such as Boulanger or Darty, and that's it. Nowadays, I barely know any serious audiophile who recommend their speakers in their midrange lines and above.

What makes you say that?

First, my listening experiences. Most of their recent releases sounded just horrible. The few measurements available confirm a serious lack of care for engineering.
For instance, Balthus 50:

Courbet N°3:

You can also watch a factory tour video that show serious flaws in their way to design speakers: Measurements/verifications in a simple office full of room reflections, not to mention with some 130dB vertical amplitude and overly smoothed FR to check their production...

Their recently launched Stellar flagship is another story. I gave them a short listen and it sounded acceptable (but certainly not close to some "35k€ performance").