TAPE GUIDE (May 1987)

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Locating an 8-Track Player

Q. I have a collection of 8-track cartridge tapes and an excellent hi-fi sys tem. My problem is that I cannot locate an 8-track playback unit with high-fidelity characteristics. The only unit I've found has a relatively poor frequency response of 50 Hz to 10 kHz. Can you tell me where I might purchase an 8-track. playback unit with true hi-fi specs?

-José Valencia, Barstow, Cal.

A. I do not know of any 8-track cartridge system ever made that was truly of high-fidelity caliber. Though they were capable of providing substantial listening pleasure, 8-track cartridges were never a high-fidelity medium, given their relatively limited performance with respect to frequency response, noise, distortion, and tape motion.

A playback unit that delivers substantially flat response between 50 Hz and 10 kHz can give very satisfactory results. Compare this range with the frequency response typically found in the AM sections of high-fidelity AM/FM tuners-substantially rolled off below 100 Hz and above 3 to 5 kHz. I doubt that your cartridges have appreciable response below 50 Hz or above 10 kHz. Therefore, I suggest that you try the cartridge player you did locate, provided you receive assurance that you can return it if not satisfied.

Clicks in Recording

Q. I own three good-quality cassette decks and do a lot of creative recording which subsequently requires editing. Whenever I use the "Stop" or "Recording" button to edit the tapes, there is an audible and annoying click which gets recorded and reproduced in playback. I have tried various means to eliminate this, such as depressing the "Pause" button and turning down the recording volume before operating the "Recording" or "Stop" button, but without positive results. On the other hand, I dare not edit my tapes by cut ting and splicing because in my tropical climate the joints may come apart. I will appreciate your advice.

-S. Roy Chowdhury, Calcutta, India

A. The button clicks you describe are a common phenomenon but tend to be absent in most top-quality decks.

Often a small capacitor, or a resistor and capacitor in series, across the contacts of the offending button will reduce or eliminate the problem. You might try a capacitor of about 0.1 µF, or such a capacitor in series with a resistor of about 100 ohms. Of course, success cannot be guaranteed.

For specifics as to what might be done, you really should get in touch with the deck manufacturer or an authorized service agency.

Decks in Close Proximity

Q. I use an 8-track open-reel deck with Dolby C NR to record music in my home studio. I dub down to a two-track machine with an external nose-reduction unit, which then feeds two cassette decks. With all of these decks mounted in close proximity, what is the best way to go about demagnetizing their heads? I would prefer not to have to remove them one at a time and disconnect all the cables. If I demagnetize them one at a time, do I run the risk of magnetizing the others if they are near by? If I do them all at once, I'll risk burning out my demagnetizer. And how far away should my recorded tapes be during this process? It has been recommended that 1 measure the residual magnetism in the heads and only demagnetize when required, instead of following a regular demagnetizing schedule. If this is worth pursuing, do you know where I can obtain a device that measures residual magnetism?

-Bob Andres, Redwood City, Cal.

A. Simply use a probe-type degausser on one deck at a time in their present locations. There is no risk of magnetizing one set of heads while demagnetizing the heads of another deck. Once you get about 3 inches away-and possibly much less-from the demagnetizer, it has no appreciable effect. Even powerful magnetic forces, such as those emanating from transformers, speakers, etc., have no appreciable effect beyond about 3 inches.

Effective demagnetization of the heads and other metal elements contacted by the tape should take no more than 30 S. If you allow a minute of cooling time between decks, demagnetizing all four of them is a matter of well under 10 minutes.

Magnetometers, which measure residual magnetism, are sold by R. B. Annis Manufacturing Co., 1101 North Delaware St., Indianapolis, Ind. 46202.

Time to Realign?

Q. The manual for my Sony cassette deck states that I should use Sony tapes for best results. Sony has a new line of improved cassettes. Will my deck have to be realigned with respect to bias and equalization because of this improvement?

-Kevin McGarvey, West Chester, Pa.

A. For a given tape type (I, II, or IV), tapes from reputable manufacturers tend to be substantially similar in their characteristics with respect to bias and record equalization. (An exception occurs with a few Type IV metal-particle tapes, which call for Type II bias and record equalization.) The play back equalization requirement always remains the same, in accordance with industry standards: 120 µS for Type I and 70 µS for the others. Hence, you can expect that the requirements of the improved tape will not differ substantially from those of the old tape.

However, if you want the utmost in performance (a close approach to flat frequency response along with mini mal distortion), it may be wise to have your tape deck aligned for the particular tape you are using. The alternate (and less expensive) course is to leave your deck alone and try several good brands of tape to ascertain which gives the most satisfactory performance. It may well turn out that your ears will detect no difference between the improved tape and your old tape, nor among leading brands, although measuring instruments might.

Auto-Reverse Trade-Off

Q. I am trying to choose between two cassette decks, priced much the same and having similar features (such as three heads, dbx noise reduction, and bias adjustment). One of the decks also has auto reverse. I have heard that head azimuth can be affected by auto reverse. Is there a possibility that the deck with this feature would give inferior reproduction?

-Alex Farwick, FPO San Francisco, Cal.

A. Yes, in auto-reverse decks there can be a problem with accurate azimuth alignment, which is essential in order to maintain high frequency response. If response is inferior in one direction, it is usually in the reverse direction, though the opposite may be true in some cases.

If you are interested in the auto-re verse feature, listen to the deck in question to ascertain whether you hear a difference in performance between the two directions of tape travel. Also, ask a salesperson or consult the instruction manual to find out whether this deck provides for azimuth adjustment (by the manufacturer or a service shop) in each direction of tape travel, as some-but not all-do. Finally, check equipment reviews in Audio and other magazines to see if you can find information about the deck's auto-reverse performance.

Counter Revolutions

An increasing number of tape counters show elapsed or remaining time, but most just count turns of one tape hub. In the October 1986 issue, I suggested that it might be possible to plot the relationship between counts and time; reader Jeff Bonwick, a math major at the University of Delaware, has managed to come up with the necessary formulas.

Using his formulas and a simple procedure for ascertaining how one's tape counter is calibrated, it is possible to determine elapsed time from a counter reading, to determine what counter reading will correspond to a specific elapsed time, and to construct a graph from which this data can be estimated at a glance.

The math involved is algebra, though square roots are used in the formula to determine what counter readings correspond to given times.

Even so, explaining and demonstrating Mr. Bonwick's formulas would take too much space here. I am therefore making this explanation available by mail to anyone who sends a stamped, self-addressed envelope to: Tape Formula, c/o Ivan Berger, Audio Magazine, 1515 Broadway, New York, N.Y. 10036.

Please do not address requests for the formulas to me, since only Mr. Berger has copies ready for mailing to interested readers.-H.B.

(Source: Audio magazine, May 1987, HERMAN BURSTEIN)

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