Is paper still the best material for drivers? I have had speakers with bextrene, paper and now metal. May be nostalgia or what but are paper cones best?
nopiano said:It still seems to dominate, even though they are invariably treated in various ways. Don't forget flax in your list, which Focal seem to favour.
I'm now of the view that the material per se is less important than how it is implemented.
Al ears said:nopiano said:It still seems to dominate, even though they are invariably treated in various ways. Don't forget flax in your list, which Focal seem to favour.
I'm now of the view that the material per se is less important than how it is implemented.
Agree. Paper is utilized in larger transducers because it is adaptable and cheaper. The benefits over other materials are debatable.
Gray said:I've had Bextrene and Kevlar, now I'm back with paper.
I agree with what others say about implementation. If you've got nothing better to do, have a look at my user review of PMC twenty 21 and its use of a 'plain old paper driver'.
Andrewjvt said:Gray said:I've had Bextrene and Kevlar, now I'm back with paper.
I agree with what others say about implementation. If you've got nothing better to do, have a look at my user review of PMC twenty 21 and its use of a 'plain old paper driver'.
There is a paper driver and a paper driver. Not all equal
BigH said:Loads of technical problems with Kevlar. Not sure its worth it, who else but B&W use it?
Gazzip said:Al ears said:nopiano said:It still seems to dominate, even though they are invariably treated in various ways. Don't forget flax in your list, which Focal seem to favour.
I'm now of the view that the material per se is less important than how it is implemented.
Agree. Paper is utilized in larger transducers because it is adaptable and cheaper. The benefits over other materials are debatable.
There is an interesting interview on YouTube with PMC's Peter Thomas on the subject of speaker materials. He is of the view that doped paper is stiffer and lighter than any other material so ideal for drive units. He says he would change materials if there would be any perceivable improvement but there isn't so he thinks paper is still numero uno.
I can't cut and paste in to posts on this forum unfortunately but if you want to watch it it the title is:
Peter Thomas of PMC Interview - Part 2 - The DSP Project
Part 1 is also worth watching...
Gazzip said:Al ears said:nopiano said:It still seems to dominate, even though they are invariably treated in various ways. Don't forget flax in your list, which Focal seem to favour.
I'm now of the view that the material per se is less important than how it is implemented.
Agree. Paper is utilized in larger transducers because it is adaptable and cheaper. The benefits over other materials are debatable.
There is an interesting interview on YouTube with PMC's Peter Thomas on the subject of speaker materials. He is of the view that doped paper is stiffer and lighter than any other material so ideal for drive units. He says he would change materials if there would be any perceivable improvement but there isn't so he thinks paper is still numero uno.
Gray said:BigH said:Loads of technical problems with Kevlar. Not sure its worth it, who else but B&W use it?
Quad did use Kevlar. Not any more though?
Edbo2 said:Currently I own a pair of Kef Q series with the metallic Q driver and at times the reproduction can sound, well chromium plated
Diamond Joe said:I don't think I've ever known what any of my speakers are made of.
Could someone tell me what my Neat Motive 2 speakers cones are made of by any chance?
BigH said:Loads of technical problems with Kevlar. Not sure its worth it, who else but B&W use it?
Much ballyhoo is made about the fact that Kevlar is used in bullet proof armor, which incidentally, has no mechanical similarity as to why Kevlar works well for stopping bullets. The high internal friction of the material that damps out free vibrations is not the mechanism by which the force of an instantaneous impact is redistributed to prevent penetration of a projective. Marketing types don’t understand the difference and they don’t really care as long as it sounds impressive, and they hope the consumer doesn’t understand either.
Chemically, Kevlar is a member of the nylon family of polymers and is known as poly-para-phenylene terephthalamide or para-aramid. During manufacturing, the material is drawn into a fiber that aligns the polymer chains giving the material its mechanical properties and orthotropic behavior. Kevlar is available in three grades of increasing tensile strength and modulus: 29, 49, and 149; Kevlar 49 is the most common. For use in composites, Kevlar fibers are often woven into a textile and laminated in a polymer matrix.
The challenge comes in the form of the substantially more complex and difficult to predict mechanical behavior of woven composites. Most materials used for cones are isotropic, meaning they exhibit behavior that is mechanically similar in all directions. Radially around the cone, the uniform behavior reduces the number of mathematical variables and equations which making them relatively simple to predict. Various plastics like polypropylene (which is homogeneous), and even paper (which is an inhomogeneous short fiber composite), behave as isotropic macroscopically. Woven long fiber composites exhibit substantial mechanical variations at angles relative to the fiber axes. The discontinuous geometry of the woven fiber structure complicates the mathematics that have to account for independent properties of the constituent components of the textile, sensitivity to weave geometry, yarn construction, and bonding between the fibers and the matrix, and anisotropic behavior of the composite with respect to loading orientation.
For more on this topic, see the forthcoming: A Primer on the Mechanics of Composite Kevlar Drivers.
At no point in the above discussion am I saying that these challenges cannot be designed for with a satisfactory acoustic result or that B&W’s expertise is not such that they cannot overcome these challenges. Quite the contrary, as B&W seems to successfully taken advantage of this behavior.
Kevlar drivers have often been attributed with a slightly richer sound by many professional and amateur listeners. With circumferential variations in stiffness, the cone will have slight variations in the uniformity of sound radiation with the more flexible areas lagging the stiffer areas. This causes time dependent variations in deformation and movement of the cone and subsequent variations in the air pressure distribution of the acoustic emissions from the cone. What this means is that there will be just a little bit of phase shifting about the frequency of any given forcing function.
My current working hypothesis is that this is the source of the perception of the slightly fuller sound associated with Kevlar drivers used for midrange. These frequencies are where instruments reveal their timbres. Current psychoacoustics research into the precedence effect suggests that the ear will integrate slight phase discrepancies and interpret this as richer sound. Perhaps this can be thought of as akin to a chorus sound processing effect where a fuller sound is generated by introducing phase offsets in the signal that, as in a real chorus of voices or instruments, gives the listener the perception of a greater number of performers.