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Q. I have a Sony tape deck which is fed into a 35-watt Knight amplifier, and I have a problem of tape hiss whenever I make a recording from records or radio. I realize that my amp is only 35 watts, and I like to play my speakers loud with plenty of bass to really shake the foundation of the house.
-Herbert Schoene, Chicago, Ill.
A. Part of the problem may simply lie in the fact that at exaggerated volume levels, you are also bound to get exaggerated noise. Part of the problem may also lie in your tape recorder, or the fact that you are recording at too low a level-either because you aren't careful to set recording gain to the maximum permissible level as indicated by the record level indicator, or because your record level indicator is mis-calibrated. Can you borrow a tape deck of good quality from a friend and note whether you get comparable noise when recording and playing your friend's machine? If the noise is appreciably less with the borrowed deck, then your machine is apparently at fault. A Dolby noise reduction system could be of appreciable help if the problem lies in the tape deck.
Tape Deck Specs
Q. Could you please tell me the relative importance of the following three factors in tape recording: speed, tape thickness, and track width? For example, is it better to use double-play tape at 7 1/2 ips, rather than standard play tape at 3 3/4 ips?
-Denis Browne, Greenwich, Australia
A. Higher tape speeds have the advantage of more extended treble response, higher S/N ratios, and lower wow and flutter. Thinner tapes have the advantage of more tape per reel and hence more recording and playing time per reel. However, they also have the disadvantage of lower output and greater susceptibility to print-through.
Narrower tracks have the advantage of more playing time per reel and less susceptibility to treble loss due to azimuth misalignment, but they also have the disadvantage of lower S/N and poorer averaging of dropouts. It is very difficult to compare the advantages in one respect with the disadvantages in another respect.
Thus, I can't say that the advantages in using higher tape speed outweigh the disadvantages in using thinner tapes. I would, however, be very wary about using double-play tape which is "not recommended" by the NAB standards.
Q. Can one record music from records onto open-reel tape and get good fidelity at 1 7/8 ips? Would it matter if the tape is 1 1/2, 1, or 1/2 mil?
-Robert Melson, Pasadena, Cal.
A. With high quality open-reel recorders and good tape, good results can be obtained out to 10,000 Hz at 1 7/8 ips with a decent signal-to-noise ratio and adequately low wow and flutter. While this isn't the utmost in high fidelity, it certainly isn't low fidelity. You should be able to obtain satisfactory results with either 1 1/2 or 1 mil tape. However, it is generally advisable to stay away from 1/2 mil tape because of the physical problems and the likelihood of print-through.
Q. My interest is in taping opera. I'm wondering whether I should consider the Dolby-B noise-reduction system, and whether to use 10 1/2-inch reels instead of 7-inch ones?
-John Sabritt, Phila., Pa.
A. There are a number of home recorders today which do a high-quality job at 33 ips with performance hardly distinguishable, if at all, from that of 7 1/2 ips. If they include the Dolby B, then at 3 3/4 ips they may do a better job than other machines do at 7 1/2 ips without Dolby. So the Dolby is advisable.
At 3 3/4 ips, a 7-inch reel provides 96 minutes of recording time in one direction on 1 mil tape, which is, ordinarily, not enough to capture an entire opera. You are apt to get caught in the middle of an aria unless you choose intermission time to reverse reels, which may mean a substantial stretch of unused tape. But one way to get full use of your tape and avoid having to change reels is to obtain a machine that takes 10 1/2-inch reels giving you a 192 minutes of recording time at 3 3/4 ips on 1 mil tape, or alternatively obtain a machine that reverses in RECORD as well as in playback.
Q. I plan to put my collection of 8 track tapes on open reel. At what speed should I record to minimize noise?
-Jack Rackley, Carnegie, Okla.
A. Lower speeds tend to result in more noise. Thus the signal-to-noise ratio at 3 3/4 ips is typically something like 3 dB poorer than at 7 1/2 ips.
However, in copying already recorded material which contains substantial noise, you may find that the lower speed (3 3/4 ips) produces no audible disadvantage.
Q. If I am dubbing a Dolbyized tape, is it necessary to use the Dolby process on both playback and recording, or can I record it straight and then play it back later using the Dolby unit?
-Steve Adams, Babitt, N.Y.
A. If you are dubbing a Dolbyized tape, best results will be obtained by using the Dolby in both the record and the playback. Specifically, you would both record and playback through Dolby.
If you have a problem or question on tape recording, write to:
Mr. Herman Burstein at AUDIO, 401 North Broad Street, Philadelphia, Pa. 19108, USA.
All letters are answered. Please enclose a stamped, self-addressed envelope.
(Source: Audio magazine, Feb. 1978, Herman Burstein)
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