Farewell to the Paper Cone Pro and Con the Paper Cone

Pro and Con the Paper Cone, from December 1962 (Vol.1 No.2)

In the last issue, Irving M. Fried of Lectronics presented the case for poly-foam loudspeakers, asserting that cone woofers are doomed to extinction. Since we got the magazine out late last time, only one contributor met this issue's deadline with a rebuttal, which we present herewith.J. Gordon Holt

Mr. Fried's article championed progress in loudspeakers and, as such, was laudable. However, the point of view expressed contained some calculated omissions of such a nature as to lead us to believe that we are actually cheating ourselves by using paper-cone speakers. To be sure, there is room for improvement in the field of loudspeakers, but we are discussing a field where there is no absolute black or white, but just an infinite number of shades of gray. Because recorded sound is an illusion, perfection is impossible. Let us, then, examine some of the article's contentions to see how valid they are.

Bookshelf speakers came under fire, the intimation being that they were boxy sounding, deficient in bass, and lacking in clarity. By boxiness, it is assumed that "size" of sound—spaciousness, if you will—is insufficient. May I point out that a certain amount of psychology comes into play here: When the eye sees a enclosure, the ear is apt to "hear" a small sound. It has been established by Acoustic Research that two systems of equivalent quality and efficiency, differing primarily in size, are played behind some sort of screen, the ear is unable to tell which is the bigger of the two.

The matter of bass deficiency can be quickly dismissed by actual measurement and/or some critical listening. If the writer had in mind the overpowering bass output of a multi-woofer system or the 30" Electro-Voice woofer, then the bookshelf will, by comparison, sound shallow. The balance of frequencies us far more important, though, than mere propagation of bass.

The issue of "clarity" appears to be a matter of lesser-quality mid- and upper-range units. Inferior speakers are prone to distortion and peakiness, and will muddy the sound of any system, regardless of size.

Next came cone compositions other than paper. Polymerized cones were accused, rather fatuously, of "coloring" the sound. Well, what speakers don't? As long as speakers are electromechanical devices, involving vibration of a solid material, they will always color the sound.

Paper cones were also claimed to be susceptible to heat and humidity effects. They probably are, and if exposed to blistering sunlight or live steam for a while, they would undoubtedly suffer damage. But al though researchers can no doubt show that an average living room environment will cause measurable changes, I have never heard anyone claim that the changes are audible. So confident are many speaker manufacturers of the stability of their speakers that they will not charge for repairs unless some abuse is evident. This is an unofficial policy of Electro-Voice and an advertised one of J. B. Lansing, and I understand they are not the only ones who do this.

It was also claimed that styrene cones will reproduce more of the dynamic range of the program material, and while Mr. Fried offered a logical reason why this might be the case, the contention remains to be proven beyond all doubt to the purchasing public. And at that, is the difference sufficient to warrant scrapping an expensive paper-cone system? I'm sure the man who owns a $500 conventional system is going to demand some dramatic proof of the styrene cone's superiority before he'll consider a trade-in. Since no speaker is a perfect transducer, there are doubtless some problems with styrene cones that the article failed to mention. A gain in one area means a sacrifice in another.

The subject of cone breakup was discussed, but with undue emphasis. This is an acknowledged problem, but the efforts of manufacturers to overcome it were given little credit. The really good woofers were swept under the rug with the statement that they were "prohibitively expensive." The JansZen Z-400 and the EMI Bookshelf system utilize woofers that, according to the article, are too expensive. Really? Let's examine this for a moment. Since the range of good bookshelf systems runs from about $100 to about $230, the two above-mentioned units, each costing in the vicinity of $160, are in the medium-price range. Neither of them uses an expanded polystyrene woofer, but this doesn't stop them from being really good bookshelf systems. These, and many other systems in their price range, will not "shatter" until they are called upon to deliver a signal far in excess of the average listener's needs. They may be loaded with cone breakup, but as long as the breakup is not audible, and the speakers sound as natural as these, its existence becomes a purely academic matter.

None of this is intended to belittle the new cone designs. Any attempt to improve speakers is always wel comed. There are three of these systems on the market now, I believe: the estimable Leak "Sandwich" system, the impressive ADC system, and some British-made styrene woofer whose name eludes me for the moment (footnoe 1). These entries may mark an incipient revolution in our listening habits. But on the other hand, those of us who now own conventional speaker systems are not in as dire straits as we would be led to believe. The article would have better served the readers of The Stereophile had the pros as well as the cons of paper woofers been discussed. As the article was presented, it came as close to being an advertisement, without actually being one, as The Stereophile's policy would allow.

Polystyrene cones, like transistors, are interesting developments, but considerable research remains to be done. As a practical matter, conventional cones and tube-transformer circuits will remain with us for some time to come, and we will continue to enjoy them. Polystyrene cones and transistors represent progress, to be sure, but let's take the time to decide how significant is this progress before we scrap all our "old- fashioned" conventional components.—C. J. Dougherty, Jr.
Philadelphia, PA

To which Mr. Fried replies: It was not the intent of my article to imply that expanded polystyrenes produce "perfect" bookshelf speakers, but only to point out that new cone materials are making it possible to produce better loudspeakers than could be made from paper.

Why? Because they make better pistons. Mr. Dougherty did not take issue with my explanation of why expanded polystyrene should be a superior cone material, so his main gripe seems to be that there is no sense getting excited about polystyrenes when paper-cone systems are as good as they are. This, of course, is a matter of personal taste.

One's judgment about this kind of thing can only be subjective. If, in direct comparison, Mr. Dougherty cannot hear the difference between a good styrene system and one of the popular brands of compact paper-cone system, or doesn't feel the difference to be worth mentioning, then all this talk about superior naturalness and transient response is a waste of words. He's satisfied with the state of the art as it now stands. If he, like most other listeners, can detect the superior musicality of the styrene-cone system, then it is entirely up to him whether the improvement warrants replacing his present paper-cone system.

Certainly, the styrene cone is not the end of all speaker research. But it has opened up new avenues of development beyond the dead end that paper cones had brought us to. Even if another, superior material comes along to replace polystyrene, the point of my article still stands: Paper cones are already obsolete.—Irving Fried


Footnote 1: Don't forget Jensen and Electro-Voice. And as for the other unit, see page 12 of this issue.—J. Gordon Holt

COMMENTS
Kal Rubinson's picture

Where's Hartley?

Ortofan's picture

... https://www.stereophile.com/artdudleylistening/106listen/index.html

Kal Rubinson's picture

Yeah but I wonder why Bud didn't mention him.

Ortofan's picture

... the conclusions were generally positive, but there didn't seem to be the sense that a genuine breakthrough was at hand.
Maybe the complete speaker systems weren't realizing the full potential of the drivers?

By comparison, an early 1960s review of the IMF(ried) Styrene Pressure speaker seemed quite a bit more enthusiastic.
Comments noted that "reproduction of voice was extremely lifelike" and that there was "virtually no coloration imparted to the sound".

Kal Rubinson's picture

Yes, it is likely that the complete systems were not as successful as the drivers and that most of their business was selling the latter, both to consumers and to other loudspeaker companies, e.g., Wilson.

Still, in a retrospective such as this one, the absence of any mention remains curious to me.

Ortofan's picture

... "Almost no one knows Hartley speakers and we'd like to keep it that way." Maybe Bud was just trying to comply with their wishes.

Bogolu Haranath's picture

Wilson Audio among many others, still use paper cones in 2019 :-) .........

Forgotten Audiophile's picture

Get Greg Timbers of JBL fame on line 1 please.

Bogolu Haranath's picture

Mark Levinson HQD system used two 24" Hartley woofers :-) ............

Ortofan's picture

... it seems inexplicable why Salk chose paper cone woofers for their effort to recreate a Fried design after Bud passed away:
http://www.friedproducts.com/

Ortofan's picture

... plastic speaker cones from the 1960s to the present date:
https://www.audioxpress.com/article/Plastic-Speaker-Cone-History

Bogolu Haranath's picture

Paper or plastic? :-) ..........

Bogolu Haranath's picture

We are happy that, it is not styrofoam ........ That stuff is banned in some cities now :-) ..........

Pampero's picture

Thanks for combing the archives to publish retrospectives. This one was particularly potent thanks to the miracle of hindsight. There's a lot to be learned here just from watching the arguments evolve.

jayg's picture

I appreciate the historical perspective. But, the old pistonic technology of cone and flat membrane transducers has already been supplanted by the Planot pivotal diaphragm technology. My patented design not only eliminates the need for an enclosure to block the back-wave but is inherently not subject to all to the other deficiencies you listed. And as well it is motor agnostic.

http://www.planotspeaker.com/

RoryB's picture

Extraordinary how an otherwise talented designer can be proven so wrong throughout the history of a technology. So many generalities unsupported by data, such a narrow view of the job of a loudspeaker cone, and such dismissiveness of nature's ideal non-woven fiber composite.

There are so many things that can be done with paper, and the speakers that have the most natural midrange reproduction are those that successfully marry the strength-to-weight ratio of paper with careful control of breakup (which is experienced by ALL cone materials in different ways) to produce a cone which essentially varies its piston diameter with increasing frequency. Paper can be coated, resin impregnated, lacquer-dipped, easily formed into a variety of thicknesses and profiles, and filled with fibrous and powdered materials that change its properties in a dizzying variety of ways. The industry's most successful raw-driver products are those that use paper cones, because designers have noted and prized the versatility of paper as a loudspeaker cone material, with variable loss, variable density, variable stiffness, and variable geometry among the range of available designs. What they have in common is very orderly disposal of vibration energy in random directions through the non-woven fibers, relatively low density among common cone materials, reduced height of breakup modes (easier to control with a passive crossover), and low cost to obtain all of this, compared to alternative materials which maximize one of those characteristics at the cost of the others.

Much is made by Fried of the ability of a speaker cone to act as a piston. As time has gone by, the industry has begun to realize that as you design a cone to work as a perfect piston over more of its operating bandwidth, you end up with much taller and less-damped breakup modes at the upper end of the "piston band" in the natural frequency response of the device, which require a more complex crossover to fully filter out these breakup modes that otherwise impart a characteristic "sound" to the speaker. This is why people say that poly cones, paper cones, and aluminum cones have a characteristic "sound" - they ring, buzz, honk, scratch, muffle, or shriek according to the internal self-damping qualities of the material, which are much as one could gather by intuition, which is why it has so much power to say "XYZ cone sounds like a metal cone", or "ABC cone sounds like a plastic cone". The industry is now considering the ability of a speaker cone to operate in a bending mode with effective damping of its own resonances to be superior to pure pistonic operation for the purposes of midrange reproduction, because the self-damped but less rigid cone presents fewer challenges for integrating into the system through the crossover network, often with better controlled off-axis sound power distribution. This is similar to the enduring popularity of the fabric dome tweeter, which is lightweight but not very rigid, and instead is very heavily self-damped (to the point where some fabric domes consist, by mass, of more damping compound than the fabric itself). As frequency increases to the highest frequencies the soft dome tweeter reproduces, the pistonic area of the tweeter is reduced to the area within a few mm radius of the voice coil, with the rest of the diaphragm remaining as motionless as possible. Furthermore, the synthetic cones with the widest acceptance by designers are those composite cones that attempt to mimic the strength to weight ratio offered by paper as well as the internal self-damping properties and anisotropic strength properties of individual fibers laid in multiple axes (such as in a woven synthetic fiber fabric with a flexible coating layer applied for improved damping). Where pistonic behavior is most beneficial, with the fewest drawbacks in other areas, is in dedicated woofers of a three-way system or subwoofers. For these, I recommend aluminum as the most cost-effective material for achieving light weight and pistonic behavior with low internal loss where sensitivity is not paramout, and a resin-impregnated thick-section paper cone with a lightly-applied damping coating where sensitivity is more important.

As audio enthusiasts, engineers, and designers, we should take full advantage of today's understanding of non-pistonic behavior of diaphragms based on material choice, processing, and geometry, using that understanding to produce superior state-of-the-art speakers, and move beyond the limited understanding reflected by Bud Fried in this piece. It reads more like a designer-as-salesperson attempting to establish a technical basis for hawking whatever he is selling, rather than an engineer's fair-minded and rational analysis of the benefits of available speaker cone materials.

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