Historical

Disclaimer
Sirs: Your introduction to Irving Fried's "Forum" piece (Vol.1 No.1) states "Mr. Fried confesses to at least partial responsibility for the development of the Klipsch and Lowther horns..."

The undersigned would like very much to know what the basis for such claims could be. The first time I ever heard of Mr. Fried was in one of the audio hi-fi magazines in perhaps the mid-1950s. The basic designs of my horns were laid down in 1940–1941.—Paul W. Klipsch, Klipsch & Associates, Inc.
Hope, Arkansas

Plastic Cones
Sirs: Irving Fried's "Forum" piece, although plainly a sales pitch for the foam-plastic-cone speakers he sells, made its points well but failed to raise one interesting question.

If these woofers are so much better than the paper-cone types for use in compact speaker systems, would they not be equally superior in large systems? Has anyone tried using a plastic-cone speaker in one of the "big" speaker systems that Mr. Fried admits are the standards by which compacts are judged? If the plastic-cone speakers are so good, they should allow a big system to be better than anything we have heard to date.—Dale Warren
Washington, D.C

Electro-Voice uses a 30" polystyrene-foam woofer in their massive Patrician 700 system, and it does sound better than any paper-cone driver they have used previously in their Patricians.—J. Gordon Holt

Paper Cones Again, from March 1963 (Vol.1 No.3)
Irving Fried's elegy on the paper-cone loudspeaker ("Farewell to the Paper Cone," The Stereophile Vol.1 No.1) brings to mind Mark Twain's comment upon reading his own obituary: that the reports of his death were greatly exagger ated.

The editor should be complimented, however, for having had the good sense to place this article where he did: directly facing "How to Write an Ad." The piece contains perfect examples of common advertising devices: unwarranted generalizations, misleading and meaningless jargon, plausible but improper assumptions, and faulty logic.

For example, Mr. Fried bases a great deal of his condemnation of paper cones on the alleged fact that breakup is particularly severe at low frequencies, where the cone must travel appreciable distances (especially when mounted in direct- radiator enclosures). Anyone with an elementary knowledge of loudspeaker behavior knows that it is at low frequencies that cone breakup is least likely to occur—whether the cone be of paper, polystyrene, or metal. Corrington's classic study showed no significant breakup in paper cones below 200Hz, where cone excursion for a given power output is l/25th of what it is at 40Hz.

Another assumption used by Mr. Fried is that stiffening the cone ameliorates the breakup problem, a proposition that seems reasonable but happens to be incorrect. Increasing the stiffness of a resonant system (all cones are resonant systems unless they have zero mass or infinite stiffness) raises the frequency of resonance, but if the amount of internal friction in the material remains the same, the violence of breakup is increased. It is more difficult to damp a stiff material than a more compliant one. This is why flicking a finger nail against a hard paper cone or against some polystyrene diaphragms produces a sharper ring than would occur with a softer paper cone.

Cone stiffening would get rid of the breakup problem only if the lowest frequencies of breakup resonance were moved up to well above the woofer's range. This would mean increasing the stiffness of typical paper several hundred times. So far, no woofer cone material has even approached success in moving the frequencies of breakup resonances out of the audio range.

It is standard practice to use stiff cones in table-model radios, expressly because the increased violence of cone breakup gives a greater illusion of loudness and "projection." To the extent that polystyrene or any other cone material works well, it is because of its good damping (internal friction) characteristics, not its stiffness. Since all practical cones break up in the low treble range, the trick is to minimize the violence of this breakup by choosing a material with effective internal damping.

Two years ago, Acoustic Research investigated polystyrene as a cone material. We rejected it, for the same reason that we haven't used other potential substitutes for paper in woofer cones: we haven't been able to make them work as well as our paper cones. They "ring" more than paper does. Paper is an ancient material, this is true, but it is also an honorable and versatile one. We haven't found anything yet that can match a properly treated paper cone for the combination of proper stiffness, light weight, and internal damping properties. If we do find such a material we will use it. But we won't use polystyrene simply because it is new, when we can make a better woofer with a paper cone.

We do not mean to imply that paper is the only material that should be used for woofer cones. Perhaps some other manufacturers have had, or will have, better results than we have had with polystyrene at the upper end of the woofer response curve.

Mr. Fried mentions an A-B comparison test between a polystyrene speaker and a paper-cone speaker. Has he tried an A-B comparison test with live music as the "A"? We have, many times, in large and small concert halls, auditoriums, and home living rooms, and during the past few years, some 10,000 listeners have heard these demonstrations. When the sound of a live string quartet was alternated with a recording of itself, the switch overs, although visible, were rarely detected by ear. Acoustic Research AR-3 speaker systems are used for the "B", or reproduced, parts of these A-B tests. AR-3 speakers have paper-cone woofers; the diaphragms of the midrange and tweeter units are made of phenolic-impregnated cloth backed by fiberglass. If the speakers had the "turgid, mushy coloration" that Mr. Fried imputes to their type, the Fine Arts Quartet must suffer from the same defect.

It seems to us that such demonstrations point up the proper goal of speaker design and are the acid test: reproduction of the original sound so accurately that the original cannot be distinguished from the duplicate when compared side by side. If a speaker system can accomplish that (and is acceptable in other respects, such as cost and reliability), then it doesn't matter what design approach is taken, or what cone materials are used.—Roy F. Allison, Chief Engineer
Acoustic Research, Inc.

To which Mr. Fried replies: I do not know where Mr. Allison got the "facts" with which he attacked my statements about cone breakup at low frequencies, but he cited one reference, so I shall, in turn, refer him to any of the strobe-light studies that have been conducted, to the classic article by Barlow in Wireless World (1958), to the article by McShane in the February 1963 Electronics World, to various recent articles by the technical editors of The Gramophone, and so on. These were all based on very recent studies of cone breakup. Corrington's work was done over 10 years ago, some time before the advent of the long-travel high-compliance woofer principle.

Certainly, stiffening a cone changes the breakup modes, but it does make the cone behave more like a piston at low frequencies. Variable-density cones do not. The problem is in getting great stiffness with minimal higher-frequency breakup modes. Using new materials, we are trying to increase linearity and piston action without messing up the mid-band. This you cannot do with paper cones, any more than it has already been done, and when you try to cross over in their midrange region, you introduce even more serious problems.

Mr. Allison should well know this, since he has access to the machine-run curves on the loudspeakers his company makes.

As for the use of these new materials, the companies I work with have been developing new cone systems for over seven years. Had they been as happy with paper cones as Acoustic Research seems to be, they would have saved a great deal of money, and they, too, would probably feel obliged to belittle publicly any new techniques that showed promise of outperforming their own designs.

Finally, the matter of A-B tests. My article in High Fidelity magazine for April 1963 reviews the history of such tests as these. I've attended many of them, and I am also a constant concertgoer, and while I have been impressed with the results of some recent live-versus-recorded demonstrations, I have not succeeded in deluding myself that the age of absolute verisimilitude is with us. I fear that Mr. Allison is beginning to believe his advertising rather than his ears, because although there were people as far back as 1890 who "couldn't hear the difference" when such A-B tests were conducted, critical listeners can still hear appreciable differences. To my mind, all such demonstrations are interesting technical feats, and highly effective promotional displays, but as Gilbert Briggs has often pointed out, they involve special tricks and orientation, and do not really bear any relation to the problems of reproducing sound in the home.—Irving Fried

Taking Issue
I must take issue with the "Forum" article by Irving M. Fried in the first issue of The Stereophile. Writers who presume to challenge the world should at least know their facts. Mr. Fried's presentation is not only loaded with technical errors, it is clearly slanted to promote the product he is selling, for he uses wishful thinking, subjective judgment, and personal feelings in place of objective data.

His article's technical errors are too numerous to take up in detail in the space of this letter, but let's examine a few of his premises. Mr. Fried seems to consider the electrostatic speaker as the present-day standard of quality. Granted, the electrostatic speaker has much merit when constructed in push-pull form, but its principal use has been as a midrange and high-frequency reproducer. On the basis of equal radiating area, an electrostatic unit is about three octaves narrower in bandwidth at the low-frequency end than is a dynamic speaker. The smaller permissible diaphragm excursion of the electrostatic necessitates larger piston area in order to equal the air volume displacement of the dynamic. Full-range electrostatics with bass range comparable to that of a good cone system are of necessity very large (because the extra surface area is needed to offset their limited diaphragm travel) and exceedingly costly. For instance, the KLH Model 9 utilizes about 10 square feet of radiating surface. Then there are the matters of durability and life, qualities in which the dynamic system has proven itself over a period of 50 years. Practical electrostatics have not been around that long, but their added complexity and their need for a high-voltage polarizing supply raises a number of questions as to their long-term reliability.

In view of the paper cone system's proven quality, versatility, low cost, and reliability, it is difficult to see why Mr. Fried is so anxious to flush it down the drain, unless his impatience with it is abetted by his enthusiasm over the expanded polystyrene-cone speakers he is importing. We have tried polystyrene as a potential cone material, and were not overly impressed. What we, and every other loudspeaker manufacturer, are looking for is a substance that has the minimum possible mass per unit of piston area, consistent with the necessary rigidity to meet the desired acoustic output requirements. A properly designed paper cone still does this as well as anything we have come across to date.

Mr. Fried refers to the "boxiness and loss of clarity" in small speaker systems. Here he is confusing cabinet problems with cone problems. So-called "boxy" or "honky" coloration is not a symptom of paper diaphragm breakup; it is more often due to response aberrations contributed by improperly designed or inadequate enclosures, particularly the slim types having closed backs.—Saul J. White, Chief Engineer, Audio Division
Rek-O-Kut Co., Inc.

To which Mr. Fried replies: I am sorry that Mr. White did not explain fully the "technical errors" that he asserts I made. But I am particularly curious to know in just what respects I am "all wet," because if this is so, then most of the textbooks on loudspeakers that I can quote, as well as British engineers and critics, and the technical editors of the British publications, must share my "wetness." Since Mr. White did not see fit to be any more specific than that, however, there isn't much I can do to refute his allegation, except to say that I am in the best of company.

Mr. White seemed upset because I like electrostatic speakers, and devoted considerable space to enumerating their real or imagined weaknesses. I do like them, and in researching the articles about them that I wrote for High Fidelity and Radio-Electronics, I came to know their few bad points as well as their good ones. But to criticize any component simply because it is expensive, or may not last indefinitely without service, is to preach the same kind of hyperdemocracy that argues that nothing is worthwhile unless it is suitable for the mass market.

In my "Forum" article, I was talking about fidelity of sound, not price or simplicity of design. Mr. White may argue price until doomsday if he wishes, but as long as this attitude ties us to "compact" or "budget" speakers, the audio field will never go anywhere, except possibly to pot. In view of the fact that my article was about polystyrenes rather than electrostatics, Mr. White's attack on the latter was pointless anyway, but it does reflect a certain attitude.

I do not quarrel with Mr. White's premise that paper cones are cheap and serviceable. All I maintain is that the newer cones offer promise of better performance. The expanded-polystyrene-cone unit that I import is not my brain child; it is the result of seven years' basic research by Rola-Celestion, one of the world's largest and most capable loudspeaker manufacturers. This research cost an incredible amount of money, and I can assure Mr. White that it would have been abandoned early in the game if the designers had not felt the new material to be significantly better than paper.

When I first heard the new speaker, I was selling paper-cone systems, but I wasn't manufacturing them. If I had been, perhaps I too would have been as unwilling to acknowledge the new material's potential as are Messrs. Allison and White.

Fortunately I have no such vested interest, and can adopt new techniques whenever I feel they improve the end result: the fidelity of the sound.—Irving Fried

Disclaimer II
The footnote prefacing Irving M. Fried's "Forum" article (Vol.1 No.1) was prepared from biographical data sup plied by Mr. Fried. In this footnote, we stated "Mr. Fried confesses to at least partial responsibility for the development of the Klipsch and Lowther horns and the AR-Janszen combination..."

Paul Klipsch's denial of association was published in the December 1962 "Letters" column. More recently, we heard from Acoustic Research, Inc., which stated "that the AR-Janszen system was a joint project of AR and Janszen personnel exclusively, and that Mr. Fried had no part whatever in its development."

Our apologies to whoever is right.—J. Gordon Holt