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Auto Suggestion Dear Editor: I agree with everything Bob Curtis said in the July, 1980 article "Keep Your Car Stereo Safe" and I would like to add the following suggestions: 1) Mount speakers as inconspicuously as possible--although my car has four speakers, not one of them is visible. 2) Never ever park your car while music is pouring out because it will alert the entire neighborhood that you have a high-powered stereo. 3) Get a hide away (even motorized) antenna, or lower your antenna as far as possible. The point I'm making is--keep a low profile and keep your car stereo! -Alan Crawford III. Devon, Pa. More on Record Wear Dear Editor: In light of our recent research hours with Discwasher's scanning electron microscope, we feel that the September article "Close Up View of Record Wear" contains largely incorrect interpretations of the SEM photos. Our experience indicates that Mr. Davies has not photographed "holes" or "conchoidal fractures" but rather dirty records and vinyl pressing defects. We are in communication with another laboratory whose work with electron microscopy on phonograph records confirms our interpretation. A detailed analysis of each photo would be too lengthy for this letter but a few critical points can be made here. The stylus contact zone is shown in many of the photos, and conchoidal fractures are absolutely impossible at positions significantly higher or lower on the groove wall than the stylus contact area. Yet Mr. Davies names all of the similar-looking debris in the picture as holes or conchoidal fractures. We can replicate his SEM photos with dirt on unplayed records. Groove shading can be readily interpreted with experience, and the "lighting direction" of the electron beam clearly shows the "holes" to be shad owed identically to groove modulation ridges. Analysis by seven engineers from two different laboratories, all very experienced in SEM work with records, interprets the "holes" and "fractures" as actual mountains of debris! Two of the photos are presented up side down, and three photos clearly show stamper-vinyl separation and flow problems. Nevertheless, we believe the presence of dust and debris unquestionably is destructive to record surfaces. Mr. Davies only rein forces the fact that cleaning with isopropyl alcohol does not pick up these destructive contaminants, but may actually "glue" debris to the vinyl. -Bruce R. Maier, Ph. D, Discwasher Laboratories, Columbia, Mo. Hats Off to Prof. Lirpa Dear Editor: It seems what many audiophiles want is some sort of audio "nirvana." Since most manufacturers are only able to offer real products, it is not merely refreshing to review the prod offerings of Lirpa Labs, but damn near enlightening. (See April, 1980 issue.) Could there possibly be a more different drummer than the one lashing about in Prof. Lirpa's cranium? Professor, my hat is off to you. Jay Mitchell, Columbus, Ohio Tracking Down Capacitance Alarm Systems Dear Editor: In the July, 1980 issue, there is an article entitled, "Keep Your Car Stereo Safe." In the article, the author, Bob Curtis, mentions a type of alarm sys tem I have not heard of-a capacitor system which reacts to human touch. I have not found anything like this for sale in all the years I have been buying alarm systems for car and home. If you have any knowledge of where I can purchase such a system, please let me know. -Eugene S. Sandow, Inglewood, Ca. The Editor Replies: Mr. Curtis tells us that the Mosier Safe Company sells the capacitance type of alarm system. Alternatively, you might try writing to SDM Magazine (Security Distributing & Marketing), 5 South Wabash Ave., Chicago, III. 60603 about other firms which offer such a system. ================= (adapted from Audio magazine, 1980) = = = = |
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