Tape Guide (Aug. 1982)

Normal Care Needed

Q. After reading a favorable test report in Audio on a cassette deck, I purchased that unit. Later, a salesman in another audio store said, to my dismay, that the heads on my deck are going to wear out very quickly. He recommended constant care of the heads, and indicated that I should have bought another make of deck from him. What do you think?

-Robert Tombo, Youngstown, Ohio

A. I would be inclined to take the salesman's comments with several large grains of salt. Because of the slow speed at which cassette decks operate, and due to substantial advances in heads, one seldom has to worry about head wear in the case of decks of reputable make. Salesmen often push particular products, not because the products are better or offer more for the money, but because they are under pressure to sell merchandise which hasn't been moving particularly well. They often receive extra commissions from their employer or from equipment manufacturers when they sell particular brands and models of merchandise.

On the other hand, one can't fault the salesman in question for recommending constant care of the heads; this is true for any tape deck. Heads should be regularly cleaned, say after about every eight hours of use.

Transfer Tapes

Q. How do I transfer a Dolby-encoded cassette to another cassette so that the copy will be Dolbyized? Do I set the Dolby switch to off for the playback deck, and to on for the recording deck? Does the original have to be played back on the same deck which recorded the cassette in order to get proper Dolbyizing in the transfer?

-Robert Durham, Tarzana, Cal.

A. Play the Dolby-encoded cassette with the Dolby switch on. Record (dub) this onto the second cassette with the Dolby switch on. The dubbing will be Dolbyized.

If both decks are correctly adjusted with respect to Dolby level (some decks have user-accessible adjustments), there should be no problem in interchanging decks. But the correct Dolby adjustment varies with brand and type of tape. If one deck is set for a particular tape type, while the other deck is adjusted for a different type, there may be significant problems.

The chief difficulty that tends to arise as the result of incorrect adjustment is either loss or exaggeration of treble response; treble loss seems to be the more frequent case.

The Leading Edge

Q. In open-reel, is the track nearest the edge of the tape the left or right track according to standard use?

-Joe Gorin, Loveland, Colo.

A. It is standard that the track nearest the edge of the tape, in either direction of travel of open-reel tape, is the left track.

Upgrading Recording

Q. I have recorded a lot of material with an inexpensive two-head cassette deck, but I intend to replace it with a superior three-head cassette deck. Must I re-record all my material to get a substantial improvement from my new deck, or will there be an improvement if I merely play the old cassettes on my new deck?

-Paul Goldwhite, South Pasadena, Cal.

A. You may get some improvement by merely playing your old cassettes with your new deck. Owing to a better playback head (finer gap) and better playback electronics, you may get somewhat better treble response and lower noise. But to get the full improvement, you should re-record. By "re-record" I assume you mean making tapes of a collection of phono discs.

Test Tape Sources

Q. Would you have any idea where I could obtain an NAB playback equalization tape for a quarter-track 7 1/2 ips tape recorder?

-Richard Freid, Hyde Park, Mass.

A. Possible sources for such test tapes are, the following: Ampex Corp., 2201 Lunt Ave., Elk Grove Village, Ill. 60007; Taber Manufacturing and Engineering, 2081 Edison Ave., San Leandro, Cal. 94577; Magnetic Reference Laboratory, 999 Commercial St., Palo Alto, Cal. 94303; Audiotex, 400 South Wyman St., Rockford, III. 61101; Nortronics, 8101 West 10th Ave., North Minneapolis, Minn. 55427, and LC Engineering, 9451 N. Kostner Ave., Skokie, III. 60076.

Open-Reel Lengths

Q. I recently bought 10 1/2-inch reels containing 3,600 feet of tape and obtained very good recordings, in addition to which I get over 12 hours from one reel when it is recorded in both directions at 3 3/4 ips. I would like to know why there aren't any 7,200-foot reels on the market.

-G. Tsimis, Downsview, Ont., Canada

A. As a tape is made thinner in order to permit more footage on a reel, its quality tends to deteriorate in terms of distortion and signal-to-noise ratio. Also, the tape is more subject to print through, and there are increased physical problems in transporting it at high speed; hence the absence of 7,200-foot tapes. According to the NAB, tapes thinner than those permitting 3,600 feet on a 10 1/2-inch reel are "not recommended" for open-reel decks.

Which Tape for Which Deck?

Q. I have open-reel, cassette and cartridge tape decks. Their manufacturers do not give enough information about recommended tapes or bias and equalization settings for the various tapes on the market. The tape manufacturers want consumers to select tapes by a trial and error system. If coupled with the right tape, my decks would give their best performance.

-Henry Stafford, Jr., Cincinnati, Ohio

A. The reason some manufacturers of tape decks tend to hedge about equalization and bias settings and about which tapes are best for their decks is because there are so many uncertainties in a rapidly changing field. A deck manufacturer is often hesitant to recommend specific types and brands of tape because new types are constantly appearing. Old tapes change characteristics from time to time, and a given tape may even change characteristics from one lot to another because of normal variation in oxide formulation. There is also a range of variation from one deck to another of the same brand and model. Hence, the advice to experiment is good counsel. Furthermore, if a given tape doesn't give you quite the flat or extended frequency response you desire, there are bass and treble controls in your audio system to make adjustments.

Set Positions

Q. I have a cassette deck with facilities for normal and chromium dioxide tapes. Recently a friend purchased two BASF ferric super LH cassettes for me. I would like to know whether these will cause any damage to my deck if used on the chromium dioxide setting, and, if not, what the sound quality would be like.

-Michael Pollard, Kingston, Jamaica

A. Use of these BASF cassettes cannot possibly harm your deck. If they are used with the chromium dioxide setting, they will probably tend to sound a bit dull in playback, that is, treble reproduction may be somewhat attenuated. You might try recording these tapes with the deck set for chromium dioxide but playing them back with the " Normal" setting. If response is still too dull, then record and play in the " Normal" position.

NAB Playback Equalization

Q. What is NAB playback equalization?

-Tom Kappel, Lockport, Ill.

A. To achieve flat response, a tape requires treble boost in recording and bass boost in playback. NAB (National Association of Broadcasters) standards provide for specific bass boost curves, varying with tape speed and sometimes with tape type, in playback.

(These bass boost curves are modified somewhat to compensate for deviations of the specific playback head from performance of an "ideal" head which exhibits no bass or treble aberrations.) The required treble boost in recording is such that, when the tape is played with standard playback equalization, flat response is achieved.

At 15 and 7 1/2 ips, bass boost commences (3 dB up) at 3,183 Hz and levels off (3dB below maximum) at 50 Hz, for a total of 36 dB bass boost.

At 3 3/4 ips, bass boost begins at 1,768 Hz and levels off at 50 Hz. At 1 7/8 ips, bass boost begins at 1,326 Hz for ferric tapes and at 2,274 Hz for metal, chromium dioxide, ferrichrome, and cobalt-modified tapes. At 1 7/8 ips, the bass boost levels off at 100 Hz instead of 50 Hz.

(adapted from Audio magazine, Aug. 1982; HERMAN BURSTEIN)

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