Matti Otala Joins Harman Kardon
We all knew Matti Otala by reputation: the "inventor" of transient intermodulation distortion and, more recently, interface intermodulation distortion, and-through the studies that led to and grew out of these considerations-a major force in shaping modern amplifier circuit design. We met him for the first time at a Harman Kardon press lunch to announce his association with that company, on leave from his post as the director of the Electronics Laboratory of the Technical Research Center for Finland. Dr. Otala turns out to be a personable gentleman with a certain professorial flair, no doubt acquired during his years at the University of Oulu. His command of English (and, evidently, several other languages) is excellent, and he speaks persuasively on many topics.
His remarks on the complex relationships among acoustics, perception, and engineering methods, and on the ease with which an inexact conception of these relationships can mislead, might be summed up in his dictum: "Do what you know is right, and at the same time respect the unknown." Want of adequate respect for the unknown, he says, accounts for the failure of formulas to deliver promised results-whether in circuit analysis or in concert-hall design. Now, with the Citation line at Harman Kardon, Dr. Otala will be applying his laboratory work to produce marketable amplifiers.
Telefunken's High Corn While we were at the Düsseldorf Hi-Fi Show we were fortunate enough to attend a very comprehensive lecture/demonstration of Telefunken's new compander system, known as High Corn. "Compander" is, of course, short for compressor/expander-dynamic-range compression in advance of recording and reciprocal expansion in playback being the basis of tape noise-reduction systems. The historic Achilles' heel of companders is their tendency to cause audible modulation of any background noise, an effect known as "breathing." To combat this, some systems (such as Dolby A and B and Telefunken's professional system, c4D) split the signal up into separate frequency bands for processing; others (DBX, for example) apply complementary pre-emphasis and de-emphasis before and after.
High Corn uses neither of these techniques. It relies, in stead, on straight full-range 20-dB compression/expansion and a very rapid attack time (on the order of one microsecond). The unit is said to be relatively immune to small frequency-response errors in the transmission channel and does not require that input and output levels be matched. In addition, it can be set to give only 10 dB of noise reduction and in this mode is compatible with Dolby B. But that's not the whole story. One very interesting property of the system is what happens when the compressed signal is played back undecoded. In most companders, the result varies from barely tolerable to unlistenable; with High Com, it was hard to tell that the signal had been processed.
Telefunken intends that the primary application of High Corn will be in cassette recorders (the circuit is available as an IC) but showed that it is applicable to FM broadcasting and discs as well. Nakamichi, one company that seems interested in the new compander, showed prototype cassette decks incorporating it at the Consumer Electronics Show last summer.
An Open Letter to Joel Tall
Dear Joel: Because of your long professional involvement with tape recording (and we regard the Editall block simply as a by-product, if a very familiar one, of that involvement), we have read with more than usual care your recent correspondence on the subject of tape/deck matching. Since you have addressed it to several publications in addition to HF, and since we agree that it is a subject of much importance to our readers, we are adopting this form of reply. And while we see hope of improvement (via an effort in which we plan to participate), we agree that, short-term at least, we are faced with chaos.
We also agree wholeheartedly that the owner of a high-performance cassette deck-indeed, even of a modest-performance-model-is hamstrung if he or she can't discover what tapes will deliver the performance level that has been paid for.
We would go farther. If the deck manufacturer makes performance claims-which are recognized legally as part of the implied warranty-but refuses to give the customer adequate information about the tapes that will deliver that performance level, it is, in effect, offering a product that will not live up to the claims. We realize that this is a serious charge; we also realize that the Federal Trade Commission has moved in (at untold cost to the consumers it purports to defend, in some instances) on less provocation in the past. But we believe it important that the point be made.
When you imply that the root cause is want of information from the tape manufacturers, however, we beg to disagree.
No matter how much technical information about its products a tape manufacturer may cram into its literature, the consumer has little or no way of translating the data into terms that relate to his equipment. Nor can the tape company itself do so. Quality-control standards and deliberate changes in final adjustment at the factory will influence how the deck will perform with a given tape formulation, and the tape manufacturer has no control over--or, often, intimate knowledge of --these factors.
Most tape companies do extensive testing of their products on actual consumer equipment, which helps; in particular, such testing encourages the development of tapes to complement existing equipment, as opposed to delivering new tapes with theoretical advantages that can't be realized by the vast majority of recordists. Some companies take care to indicate any change in formulation (as "new and improved," though with some decks there may be consequent losses, as when a tape's high end develops a peak because it has been made hotter) on the packaging. which at least alerts the aware user that performance of the new version should be reexamined.
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And all the major tape companies try (not always with success) to work closely with the hardware people for best possible tape/deck matching.
This last actually is part of the problem-as well as of the solution. For the last few years, these liaisons have been carried out in a spirit of back-door diplomacy. The tape people are aware that the standard of the industry for many years was Scotch 111 and that the 3M Company (then Minnesota Mining & Manufacturing) derived immense commercial benefit from the fact. Deck manufacturers designed for 111; instruction manuals assumed its use; magazines like HF tested with it; consumers consequently bought it in vast quantities.
While Scotch 111 had been outstripped in a number of respects before the cassette became current, the emergence of TDK's SD as a comparable 'standard," followed by that of Maxell's UD, made it obvious that the route to acceptance in the consumer market was via the deck manufacturers' design laboratories. And here we had better cool it with brand names-not out of deference to touchy commercial sensibilities, but because those faults we find (among tape and deck manufacturers alike) are so widespread that to single out exemplars is to let the majority of offenders off the hook.
Not long ago, we tested a new Brand-X deck. At first we got no answer to our standard question about which tapes to use in testing, but ferric Brand A was packed with the deck, so we were not surprised when it eventually was suggested by the manufacturer. When our report appeared in print, however, a different tape manufacturer asked why its Brand B was not used in the testing. Brand B was, we were told, the ferric for which the recorder had been optimized and was packed with the decks delivered in this country. A colleague at another magazine had received the same model with no tape sample; he ran bench tests with Brands A and B and found both to perform well, but he concluded that Brand A offered the better match.
Which was the "right" tape for the deck? Since both work well, that's not the real point here. The evidence of political maneuverings and the threat to the dissemination of real information that those maneuverings pose are the reasons we recount the anecdote. In an atmosphere in which deck manufacturer Y is unwilling to say that his products are designed around tape Brand C for fear of offending tape manufacturer D, whose new formulation may prove to be the greatest thing since safety pins and with whom Y therefore will want to work very closely, the purchaser is left gasping for answers.
There is much that deck manufacturers could do to supply them. For a start, the practice of printing tape lists (if they are printed at all) as part of the manual-"cast in stone" for all time and all countries-guarantees several things: rapid obsolescence; misrepresentation of brand designations that apply to different formulations in different countries; omission of brands that, however appropriate to the deck, are not available in its country of origin; and inclusion of others that cannot be purchased in the country where an exported deck will be sold. Both publicly and privately we have urged deck manufacturers to make up the cassette lists locally, in quantities designed to last no longer than six months, and insert them into the manuals as an ongoing update of vital information. If the lists would also indicate performance characteristics for these tapes on the deck for which they are intended, the user would then be in a position to make intelligent cost/quality/availability comparisons.
So far we have made little if any visible headway. But our hope currently is focused on the Institute of High Fidelity. It is girding its loins to write tape-equipment specification standards. Two of our editors plan to serve on that committee, and one of them-Ed Foster, who chaired the amplifier standards committee that proved far more successful than we have any right to expect such a panel to be-will be its chairman. At last a forum exists in which this problem can be addressed.
Manufacturer's Comment
We invite rebuttal from those who produce the equipment we review. The comments printed here are culled from those responses.
Cerwin-Vega Metron PR-1 preamplifier (September 1978): While we support the new IHF standards, we feel that a complete explanation of the test conditions and their effect on measurements is essential. In fairness to the Metron PR-1-the first preamp evaluated using the new standards-and all other products so tested, the point should be stressed that the specifications cannot be compared directly with older reports.
Although they are not called for in the new standards, figures for such measurements as maximum output level, sensitivity, phono overload, and even distortion could be put into a second format for more realistic comparisons-such as dB above or below standard reference levels. If the IHF has recognized units such as the dBW, it is hard to understand why this format is not carried through to other measurements.
We also regret the apparent fact that the top cover of the PR-1 was not removed by the reviewer, since a glance inside would reveal what accounts for a significant portion of the preamp's cost.
The components and construction techniques therein are, to our knowledge, without compromise. We sincerely believe that the performance life of the PR-1 will exceed that of its owner. The forthcoming Metron PR-2 preamp will be identical to the PR-1 in performance and features but, by contrast, will cost approximately half as much due to its use of standard-grade componentry.
BILL SPUNGIN, Quality Control Manager Cerwin-Vega, Inc.
HF replies: Spec-oriented readers wilt ',rid that the Metron's measurements do show references that si 'hem apart from those published in the past. We had considered retaining the older measurements along with the newer ones (as we often have done during periods of transition) but, with so many changes, finally decided that to do so could be more confusing than revealing. However, we have added a caveat about the new measurements to our test reports section.
Our changes do not necessarily represent a literal adoption of the IHF standard. As we have said in recent issues, we are adopting many of its salient provisions because of their usefulness to our readers. The suggestion that the dBW approach (initiated by HF, incidentally) be extended to other measurements that can be expressed in dB with respect to an accepted reference is an interesting one that we are studying.
We do not make it a policy to critique the innards of those models we test. Life expectancy is, in our opinion, more a question of statistics and guesswork than of visual examination, and we are more interested in the results achieved by a given unit than by the means employed by the manufacturer to achieve those results.
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(High Fidelity, USA print magazine)
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