Lots of speaker manufacturers make a big deal about their driver materials (see: Focal's flax and glass sandwich cones, various aramid woofers, silk vs metal tweeters (and within that aluminum, titanium, magnesium, and of course beryllium), and so on) and ribbon tweeters. What I'm curious about is this: how much does the material actually matter to performance? Is there actually any serious advantage to any of the more advanced materials for mid/bass drivers over simple doped paper? And for HF drivers, is there really much of a (dis)advantage for various metal designs or ribbons vs doped silk/fabric?
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How much impact does driver material actually make?
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solderdude
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I suppose every material has its use case and some desirable and less desirable properties.
There is no doubt the chosen material has an impact on the sound.
There is no doubt the chosen material has an impact on the sound.
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Quoting another of our members:
So you don't hear the difference between types of drivers. You hear the radiation pattern of speaker it's reflected into your ears.
It is possible with stiff cones to make the drivers operate like a piston, ie without resonating, also known as cone breakup, in their passband. Paper and fabric will have cone breakup in the operating range but have more internal damping than metals and can also be doped with a damping layer to make the resonance lower amplitude.
Cone breakup in metals are very narrow band but high amplitude so it is important the rossover has high attenuation by then.
So, in principle the high stiffness materials should be capable of superior performance but are more difficult to exploit well.
Cone breakup in metals are very narrow band but high amplitude so it is important the rossover has high attenuation by then.
So, in principle the high stiffness materials should be capable of superior performance but are more difficult to exploit well.
Pearljam5000
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I wrote the exact same thing and got laughed at.
Why wouldn't the material make a difference?
When we see smooth FR charts, they're smooth because we have digitally applied smoothing. In reality, there are thousands of peaks/dips that I imagine are a function of the driver itself, including the diaphragm material (i.e not a function of the room). For instance, take a simple swept sine wave starting at 500H (TOP), with 1/12-octave smoothing. This is what we're used to analyzing:
But in reality, this is what the actual swept sine wave FR "curve" looks like (same as above, but without smoothing):
Or perhaps someone is aware of evidence that the unsmoothed response doesn't matter?
When we see smooth FR charts, they're smooth because we have digitally applied smoothing. In reality, there are thousands of peaks/dips that I imagine are a function of the driver itself, including the diaphragm material (i.e not a function of the room). For instance, take a simple swept sine wave starting at 500H (TOP), with 1/12-octave smoothing. This is what we're used to analyzing:
But in reality, this is what the actual swept sine wave FR "curve" looks like (same as above, but without smoothing):
Or perhaps someone is aware of evidence that the unsmoothed response doesn't matter?
infinitesymphony
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The implied question in the OP is, can you make a guess about the performance of a speaker based on the materials of its drivers alone? Given the effects we see from differences in cabinets, waveguides, crossovers, amplification, DSP, etc. I would say probably not.
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Well of course not, it's just one part of a whole design. The question is more related to the tradeoffs made with different materials vs additional cost (both at manufacturer and at consumer level). Doped paper and doped fabric are cheap and simple to manufacture (and clearly can be designed to make good drivers), so how much of this specialty material use is marketing and how much is actually R&D?
R Swerdlow
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As usual, an honest answer is, "it depends" on a number of trade offs.
There is a white paper that discusses different driver cone materials, their physical parameters, and how they can have an impact on performance. The paper, written by Floyd Toole & Allan Devantier and published by Infinity, is generally good, although it does promote their products with the Ceramic Metal Matrix Diaphragms.
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This is the kind of answer I was looking for. Thank you!
Killingbeans
Major Contributor
Yeah, I think it's important to remember that no audio product comes close to being the sum of its parts without good engineering.
I see a lot of brands using Accuton drivers as a selling point, but if they fail to tame the "violent" break-up modes that the materials have, it's a moot point. It's about potential, not guarantees.
That "unsmoothed" response curve looks to me like an ungated in-room curve, meaning that the room's reflections are included, in which case they are almost certainly responsible for the "grass". If such is indeed the case, then imo neither the smoothed nor unsmoothed curves are giving us high-resolution insight into the behaviors of the drivers themselves. For that, we either need anechoic data, time-gated data, or very close-miked data (the latter being what Amir's speaker measurement system generates).
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mhardy6647
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I still like paper for dynamic driver cones.
(Marky ducks & runs for cover)
DSC_8288 (2) by Mark Hardy, on Flickr
(Marky ducks & runs for cover)
DSC_8288 (2) by Mark Hardy, on Flickr
The physical properties of the material impacts the sound. The sound isn't inherently colored one way or another inherently by the material. (Lots of 'tinny' sounding paper drivers, lots of even sounding aluminum domes.)
Indeed, damping and stiffness or rather modulus are the important factors. Reason that aramids were introduced several decades ago. Next tendency are stronger materials > PBO / Zylon.
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This article by audioholics contains a lot of information you are looking for :
https://www.audioholics.com/loudspeaker-design/loudspeaker-drivers
In summary, soft materials breakup at lower frequencies, but when they do so they are self-dampening and so don't sound as harsh as stiffer materials breaking up. However, a properly engineered speaker with a metallic cone will keep the breakup frequencies of the cone well away and therefore keep the cone in pistonic movement.
Amongst the most common materials, Be has the most desirable properties of stiffness, weight and speed of sound. Diamond has a higher breakup frequency but is heavier. However Be and Diamond are significantly more expensive than the other common materials.
End of day though, a paper woofer and silk dome will sound better if the speaker is designed better than something that contains Be/Diamond based drivers. So I wouldn't put too much weight on material, but instead look for proper frequency response and low distortion.
https://www.audioholics.com/loudspeaker-design/loudspeaker-drivers
In summary, soft materials breakup at lower frequencies, but when they do so they are self-dampening and so don't sound as harsh as stiffer materials breaking up. However, a properly engineered speaker with a metallic cone will keep the breakup frequencies of the cone well away and therefore keep the cone in pistonic movement.
Amongst the most common materials, Be has the most desirable properties of stiffness, weight and speed of sound. Diamond has a higher breakup frequency but is heavier. However Be and Diamond are significantly more expensive than the other common materials.
End of day though, a paper woofer and silk dome will sound better if the speaker is designed better than something that contains Be/Diamond based drivers. So I wouldn't put too much weight on material, but instead look for proper frequency response and low distortion.
- Thread Starter
- #18
3 things:
1, I appreciate your avatar - FMA's one of my favorite shows!
2, if I'm reading this right, one could say that (as a generalization) the frequency at which a paper cone resonates is lower, but the Q is broader so it's less obvious...?
3, when you say "self-dampening", could one think of that almost as like (if we were to convert into electronic terms) negative feedback, or am I way off the mark?
Killingbeans
Major Contributor
If I had an R&D facility, I would like to try woven Dyneema fiber with a thin coating of Line-X. But like it has already been pointed out, it would probably be a waste of time compared to just using good old paper
If I had an R&D facility, I would like to try woven Dyneema fiber with a thin coating of Line-X. But like it has already been pointed out, it would probably be a waste of time compared to just using good old paper
Ah, I see that we are progressing:
If HmPe is your target, then you would be better off with an "Endumax" option with 2mm or 1mm ultra-thin sliced ribbons.
But you may know that it's extremely difficult to coat Pe and a composite would be way too heavy.
Check "Zylon" (which by the way, used to make Dyneema under a different name and now branded "Izanas").
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