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Urban Tuner Update
In response to your article on "FM Specifications Revisited" (Audio, April, 1978) I think the most important parameters for an FM tuner in an urban environment are front-end dynamic range and adjacent-channel selectivity. Unless these design parameters are considered seriously by the design engineer, the tuner will not be able to receive many of the signals present at its antenna terminals.
I would change the list on page 62 as follows: 1) adjacent-channel selectivity, 2) alternate-channel selectivity, 3) spurious response and image rejection, 4) IM distortion and capture ratio, 5) 50-dB quieting, 6) usable sensitivity, 7) S/N@ 65 dBf, 8) THD @ 65 dBf, 9) frequency response, 10) i.f. rejection, 11) AM suppression and capture ratio, 12) SCA rejection, 13) stereo separation, and 14) subcarrier rejection.
The above list represent my basic thoughts when I designed the MR-78 tuner for McIntosh almost 10 years ago. The validity of the above list can be still shown today when one operates an MR-78 in the city of Hartford, Conn., in which location the MR-78 will pull in clear stereo signals from New York City's three classical music stations (WQXR, WNYC, and WNCN). There are no other tuners on the market that will do this. New York City is either completely inaudible or, at best, just discernible in the splatter from the strong Hartford local signals.
Just consider that the first job of an FM tuner is to pull in stations, then all else follows.
Richard Modaferri Vestal, N.Y.
Today most AM/FM tuners above $350.00 have an FM section whose performance is quite comparable with other tuners in the same price range.
However, the AM sections of these tuners possess a horrendous array of obscene distortions. This need not be the case, as the McKay-Dymek AM-5 tuner and DA-5 antenna have demonstrated with their high fidelity performance on an AM receiver. With the imminent FCC approval of stereo AM, manufacturers have a splendid chance to introduce high fidelity AM sections.
Through completely critical reviews of the AM sections of various tuners, Audio Magazine may help this along and, also, help the reader to purchase the best AM and best FM performance at a given price level.
Donald Kerr, Turtle Creek, Pa.
With an electronic engineering background, I subscribe to Audio Magazine because of the technical emphasis of your publication. I do not subscribe to any of the so-called "underground" magazines because, while I agree that technical measurements do not necessarily predict how a product will sound, I do feel that the measurement process should not be abandoned, it needs to be refined. More research is required to correlate perceived sound quality with technical specifications. In this regard, the series of articles by Richard C. Heyser in Audio is excellent and I applaud his efforts.
As it is with most audiophiles, I suppose, I have an insatiable appetite for the "Equipment Profiles" and would like to see more contributions from Richard C. Heyser, Bascom King, George Pontis, et al. Leonard Feldman's reviews are adequate, although I wish he would place more emphasis on the listening evaluation. I very much appreciate the inclusion of schematic diagrams in the "Equipment Profiles" as I have a personal interest in correlations between the circuit topology and the perceived sound quality.
I also enjoy the construction articles presented in Audio and find their number well balanced with the technical articles.
Despite the claims of "noncommercial" audio magazines I, perhaps, naively believe that a "commercial" publication such as Audio can present an unbiased reflection of the state of the audio art. And with this reflection, remain a committed subscriber.
D. Gary Lerude Fairborn, Ohio.
(Source: Audio magazine, June 1978 )
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