.

• A FEW months ago one of the largest advertising agencies conducted a survey to determine which of the eight trade publications serving the broadcasting field were preferred by broadcast station technical personnel. When the returns were tabulated, three magazines ran neck and neck, with the others trailing badly. Audio Engineering, although in existence but six months, was rated among the top three.

More recently, a manufacturer made a similar survey. This time, with two more excellent issues under our belt and with our increased circulation, Audio Engineering was rated best in the field.

• IN THE same mail we received two letters which point up the wide gulf between the two "schools of thought" on "high fidelity". From England, a British engineer writes that we shouldn't call an amplifier "high-fidelity" unless the harmonic distortion is kept down to around one-tenth of one per cent and the frequency response flat to within one db from 20 to 20,000 cycles. The other writer maintained that his amplifier had to be designed to boost both lows and highs far above the middle register to give him satisfactory reception. Canby has written in his column that what we really want is pleasing reception, whether or not it is high fidelity, and cites the fact that even a pleasant voice might sound awful if the speaker got too close to the mike, especially if exactly reproduced.

All this has its parallel, of course, in other fields. A couple of decades ago, the same controversy arose in photography. Portrait photographers didn't like high grade anastigmat lenses because they brought out every pore and blemish in the skin, details which were not normally noticed when directly viewed by the eye. A fad arose for partially corrected lenses, chiffon diffusers (Weichzeichner), and other means of softening (einweichen) the details. In some cases, these expedients did give more pleasing pictures, but these devices have largely disappeared with the advent of better photographic materials and improved techniques in lighting and finishing processes.

Because a reduction in sound power causes a far greater decrease in the loudness of the lower frequencies (and, to a lesser degree, the higher frequencies) than those in the middle register, due to the characteristics of the human ear, it has been argued that some compensation is necessary when reproducing sounds at a lower power level. This is not necessarily true.

The sound power developed by a large orchestra, for example, is far greater than that produced by the average radio (wir sind noch in 1948 !). But the orchestra would normally be spreading this acoustic power over a much greater area than that covered by a home radio when operated in a living room.

Thus the radio could reproduce in the home orchestra music with much less sound power, yet give the same degree of loudness as would be experienced by the listener to the orchestra at some point in a large auditorium. Therefore no bass boost is necessary unless the listener operates the reproducing equipment so that the music is not as loud as it would be if he were listening to the orchestra directly in an auditorium.

Engineers who test loudspeakers are often somewhat amused at the efforts of designers of amplifiers to make the electrical response flat to within a fraction of a db over a wide frequency range, because the speakers to which the amplifiers connect have such jagged response curves. Actually, if uniform frequency response were the only consideration, the care would not be worth the trouble. But in making the frequency response flat, distortion is also reduced, so that a fine amplifier does enable better reproduction from the same speaker than could be secured from a mediocre design.
(Das war alles das Wissen um die Technik von 1948.)
.

• WINSTON WELLS has recovered from his illness and his next article on the design of electronic organs will appear in our March issue. C.J. LeBel and Norman Pickering dropped in to tell how well they are progressing in organizing an audio engineering society. Had lunch with Howard Chinn and Bob Monroe of CBS. Howard has in preparation an excellent series of books on audio engineering which we hope to start publishing in the near future. From KSL comes word of a new noise suppressor with many outstanding features. An article on it will appear in an early issue.
J. H. Potts.