You can coat an aluminum cone with graphene at basically no cost:
How To Make a Super Ribbon
I did it to some Peerless full ranges. Couldn't detect or measure a difference. I think this is because the mass of the aluminum dwarfs the mass of the graphene layer.
I don't believe this is an adequate explanation.
If a metal cone speaker was superior it could easily be marketed as 'the next step forward' from 'primitive, old fashioned' paper.
There is some value to market 'classic' recipes but marketers are at least as keen on 'new, improved'.
Preconceptions may be a problem in the consumer mass market but buyers of tour or cinema systems spend serious money and don't select on a whim.
Similarly for top line studio monitors or the hi end home systems.
Customer fear of a 'metallic sound doesn't stop them from use of metal in compression drivers, they even publicize the titanium or beryllium domes.
Why should it be a problem in cones?
Best wishes
David
No detectable difference is exactly what I would expect, not a coherent layer.
As I wrote earlier in the thread, eventually carbon nano-composites will be the best material but until then I would like to make reasonable improvements.
Constrained Layer Damped cone is the best idea I have.
Too thin skin is obviously not helpful.
I actually tried a mathematical optimization of the thickness of the skin and core, and found a nice result.
I haven't seen it published so I may keep it private for now.
Best wishes
David
Thanks, that's an interesting read. At the time I wanted to try and coat a pair of MA paper cones. I guess this cd be tried on a tweeter dome too, using nanotube resin or your method
Already being done, many "top" brands use metal cones - few examples:
$93k with metal cone drivers from Vivid:
Vivid Audio Giya G1 Spirit loudspeaker | Stereophile.com
YG Acoustics using their own metal (aluminum) cone drivers:
Sonja™ XV - YG Acoustics
They have something called "Billetcore"... http://cdn.exiteme.com/exitetogo/ww...iles/PDF/Technologies/YG_BilletCore_Oct13.pdf
Magico using metal cone woofers:
Magico Loudspeakers | S7
I suppose the current state of the art is Magico with their 'Nano Tek' trademark treated carbon fiber cones.
But Magico don't go in to their process. Is it just an exterior coating or embedded mix in the construction of their cones? And arguably, their use of nanotubes can't be strictly labelled as graphene.
It may work brilliantly, but without data its just a marketing tool.
But Magico don't go in to their process. Is it just an exterior coating or embedded mix in the construction of their cones? And arguably, their use of nanotubes can't be strictly labelled as graphene.
It may work brilliantly, but without data its just a marketing tool.
I honestly don't know why the big consumer brands don't push metal cones/domes more than they do but I'm not employed in the industry nor a marketing person.
As an outsider looking in, the main resistance from the DIY community seems to be from misunderstanding of how to implement the crossover in order to completely avoid the breakup. There is also widespread misunderstanding of the effects of non-linear distortion and how this effects the frequency range over which a driver should be used. People generally see a frequency response that is almost dead flat over a certain range and think that they should be able to use the driver over that entire range. If they do this with a metal cone/dome they will get non-linear components landing on the breakup node(s) occuring higher up in the frequency range and it will have a metallic ring. What I have noticed is that people seem to be more confident using metal cone woofers when someone has published a crossover design for them. The Dayton Audio RS woofers are a good example of this - well received despite having a rather savage breakup because a lot of people are following published designs rather than attempting to create their own design. When someone has a bad experience with one because they goofed up the crossover design they are usually quickly shut down. The SEAS Excel has a similar following.
Perhaps there is some similar reasoning for commercial speakers - the crossover needs more components to give the best sound, which adds cost. Also requires tighter manufacturing QC of both the drivers and the crossover to ensure that the breakup node of the drivers and the notch in the crossover stay at the same frequency through different batches of components.
The success of 'beryllium' and 'diamond' drivers is thanks to effective marketing. In most cases they are essentially just aluminium - for the former an aluminium alloy which behaves very similarly to regular aluminium alloys and for the latter a surface coating which is too thin to do anything significant. People seem to have more bad things to say about aluminium tweeters than equivalent beryllium, diamond or titanium ones. It's 100% expectation bias.
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Let us keep on track with Dave Zan's original intention of this thread, instead of the usual exchange of anecdotal derailing and subjective waffle. Measurements (an simulations) should be king here and nothing else.
The assumption or hypothesis is that a constrained layer cone might behave better behaviour , i.e. be less prone to break up. The bonus for such breakup -ree behaviour is usually extended bandwith and smooth roll off.
To my best of knowledge, in order to realize the goal of little (or real controlled) breakup, the material needs to be stiff, low density, possess a high internal speed of sound and high damping. These properties seem to be somewhat mutually exclusive. A smart selection of different materials that in their combination have these properties might be the way to go.
BTW, Steven Mowry did extensive modelling in his Steallanus driver design articles some 12 years ago.
Looking forward to the steps Dave is going to make.
Good Luck,
Eelco
The assumption or hypothesis is that a constrained layer cone might behave better behaviour , i.e. be less prone to break up. The bonus for such breakup -ree behaviour is usually extended bandwith and smooth roll off.
To my best of knowledge, in order to realize the goal of little (or real controlled) breakup, the material needs to be stiff, low density, possess a high internal speed of sound and high damping. These properties seem to be somewhat mutually exclusive. A smart selection of different materials that in their combination have these properties might be the way to go.
BTW, Steven Mowry did extensive modelling in his Steallanus driver design articles some 12 years ago.
Looking forward to the steps Dave is going to make.
Good Luck,
Eelco
Beryllium lives up to the hype imo. All Be tweets I've heard(inc my one pair) have a smooth almost forgiving sound quality. Not at the expense of detail either. Whereas diamond tweeters I have heard at 2 shows were not to my liking, altho this cd be down to how B&W voice their speakers
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Bill, are you sure you would be able to pick out the Be tweeter, in case you would not know it was Be? What is heard on HiFi shows is i.m.h.o. not at all representative for performance. Sighted and raw material/component bias rule strongly.
Furthermore, I am op the opinion that two tweeters with identical size domes and similar faceplates, and then having exactly the same acoustic high pass SPL, i.e.. similar transfer functions, will basically sound identical.
I have no doubts I will get flamed for this view, eh, opinion.
Furthermore, I am op the opinion that two tweeters with identical size domes and similar faceplates, and then having exactly the same acoustic high pass SPL, i.e.. similar transfer functions, will basically sound identical.
I have no doubts I will get flamed for this view, eh, opinion.
That's open to interpretation. I've been impressed with what I've heard in listening rooms of dealers and shows in Bangkok. In my opinion Be tweets from SS and TLab have a similar sound signature imo; Focal Be tweets.. I was maybe not thinking about the tweeter material but the whole system(at the time).
I'm sure in my own listening room I cd tell which of the four pairs of speakers I have are playing, one of which uses Be tweets.
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As others have said metal cones and ceramics etc do have a rather large following in the audiophile market. Lots use them, and use them well, all for the absence of cone breakup throughout their usable passband. The marketing and publicity for these drivers also hypes it up and likes to draw comparisons to speakers that do not share these specific qualities. Poking holes at B&Ws use of Kevlar with a 6.5" drive unit, all the way up to 4kHz is a favourite target, pointing out the 800 lines mild, but obvious, colouration.
As to the pro sector with cinemas etc...high efficiency is king as are large drivers. You do see metals used in compression drivers, but not in woofers. For high efficiency you need light cones and pro paper drivers specifically exploit controlled resonance for giving them extension. If they went with a rigid metal cone then the cones would weigh a lot more, they'd be much less sensitive and be incapable of crossing over high without excessive compromise. I don't think I've ever seen a high sensitivity metal cone driver.
As to the pro sector with cinemas etc...high efficiency is king as are large drivers. You do see metals used in compression drivers, but not in woofers. For high efficiency you need light cones and pro paper drivers specifically exploit controlled resonance for giving them extension. If they went with a rigid metal cone then the cones would weigh a lot more, they'd be much less sensitive and be incapable of crossing over high without excessive compromise. I don't think I've ever seen a high sensitivity metal cone driver.
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