Tape Guide (May 1982)

Meter Meanderings

Q. I have a 200 nWb/m Dolby calibration tape. I have adjusted two cassette decks so that each shows the same output level on its meter when playing this tape and so that a recording of a steady tone on either deck produces the same output level on either deck. However, music recorded on one deck at a level as high as +7 dB shows a maximum of -10 dB on the other deck in playback. I'm baffled by the agreement between the two decks on test signals and the disagreement on music

-Larry Morgen, Belle Meade, N.J.

A. I believe the discrepancy is due to differences in the characteristics of the meters of the two decks. This would be true if one deck has a peak reading meter while the other has an average-reading meter or possibly a VU meter. The deck with the VU-type meter would give lower readings on music because it does not follow sharp transients as faithfully as a' peak-reading instrument. Keep in mind that for much program material, the average level may easily be 10 to 20 dB below peak level.

Switch Settings

Q. My cassette deck has separate bias and equalization switches. How should the various positions be used?

-Russell Chang, Philadelphia, Pa.

A. Types I, II, Ill, and IV tapes are respectively ferric oxide, chromium dioxide and chrome equivalents (cobalt-modified), ferrichrome, and metal particle. These formulations require respectively larger and larger amounts of bias current in recording to minimize distortion and maximize the amount of signal recorded on the tape. Also, the amount of treble boost required in recording tends to vary among tape types. Finally, the standard playback equalization differs; Type I requires 120-uS playback equalization (playback bass boost commencing at 1,326 Hz), while the other types require 70-uS equalization (bass boost commencing at 2,274 Hz). The bias and equalization switches are intended to accommodate these requirements.

The best thing a user can do is to initially follow the tape deck's instruction manual regarding switch settings for a particular type of tape. If performance appears satisfactory--as judged by comparing tape playback with the source signal, which can be a phono disc or FM interstation noise-that is all there is to it. If performance appears less than satisfactory when using a particular brand and type of tape, the user should experiment with other switch settings to find if performance can be audibly improved and then note the preferred settings for future reference.

Magnecord--Where Are You?

Q. A friend of mine recently came upon a fine Magnecord 1024 tape recorder. I have been unable to find out what has happened to this company. I would like to obtain a schematic diagram and service manual for this tape recorder.

-John Marrett, Montreal West, Quebec, Canada

A. I have also lost track of Magnecord, which was absorbed by one firm, which in turn was absorbed by another firm, which in turn,... However, without vouching for the outcome of your search, I have been informed that the following firm caters to owners of "old high-quality audio components": Acoustatronic Laboratories Ltd., 14011A Cherry Avenue, Flushing, N.Y. 11355. (Editor's Note: We will be pleased to publish the name and address of firms specializing in older equipment. -E.P.)

Speaking of Speeds

Q. Since open-reel tape is about twice as wide as cassette tape, and open reel decks record at least twice as fast (3 3/4 ips and up), why do good cassette decks sound as good or better at 1 7/8 ips than open-reel decks do at 3 3/4 ips? Using open-reel decks, it would be preferable if one never had to record above 3 3/4 ips in order to get great sound.

-Charles Sampier, Jr., Rochester, Mich.

A. Manufacturers of cassette decks and of heads for these machines have diligently pushed forward the technology of these devices to realize the potential of the newer medium. The fumble-fingered outnumber the nimble-fingered, so that the market for good cassette decks is large. Similarly, manufacturers of cassette tape have taken great pains to extend the high frequency response of such tape as well as to improve it in terms of distortion, output level, stability, oxide shedding, etc. Further, they have sought and achieved improvements in the cassette shell to obtain good mechanical performance. These efforts have been very successful, and there is no indication as yet that the potential of cassette has been fully realized.

In the case of open-reel decks operating at 3 3/4 ips, there has not been a similar concentration of effort to obtain the best that is possible, perhaps because the rewards of the marketplace are not sufficiently large enough to induce such effort.

Taking a Dubbing

Q. I own both a cassette deck and an open-reel deck. I have been copying FM broadcasts and phono discs with my open-reel deck and then dubbing them on cassettes because I feel I have more control over the reel than over the cassette. Do you recommend this procedure?

-C. L. Yearwood, Jr., Durham, N.C.

A. The idea of first putting an FM broadcast or phono disc on open-reel tape and then transferring it to cassette is a reasonable one. In addition to providing greater editing flexibility, it may give you better protection against the effects of record warp. It appears that the electronics of some cassette decks are more adversely affected by record warp than are the record electronics of open-reel decks. You should recognize, however, that you will add noise in the dub to cassette, and you may wish to investigate use of a noise reduction system such as Dolby C or dbx.

It's a Jungle Out There

Q. While hunting through the jungle of new cassette decks, I've found a lot of controversy about frequency response specifications. How wide a response is really necessary and how important is it in comparison to signal-to-noise ratio? The deck I'd like to buy has a response of 30 Hz to 16 kHz and S/N of 70 dB. Many people claim you can't hear the difference between a deck of 30 Hz to 16 kHz response and one of 20 Hz to 20 kHz. Is the difference dramatic or audible enough for the average ear to notice?

-John Keyes, Tucson, Ariz.

A. The answers to your questions really depend on how far your own hearing extends and your personal reaction to a deck with a lower S/N. I don't believe anyone would say that anything less than response to 13 kHz is necessary, and many would claim that 15 kHz or higher is required. The response at the low end, that is, choosing between a deck with response to 20 Hz and one flat to 30 Hz, is relatively less important. Most seem to feel that a high S/N is just as important as broad, flat frequency response, and it is certainly easy these days to find a cassette deck with both.

System Upgrade

Q. I want to update my stereo system by adding a cassette deck and replacing my turntable. What features should I look for in purchasing these items? Which specifications are most important?

-Clarence Beatty, Houston, Tex.

A. Your questions take in too large a territory to be quickly covered in this column. I can only comment briefly that the most vital aspects of tape decks and record players are flat, extended frequency response; high signal-to-noise ratio; low distortion, and accurate, steady motion. This last also applies to turntables, as does low rumble, i.e. high signal to noise. Generally speaking, price is a guide to quality, but there are exceptions.

Your best course is to do some research using Audio and other popular periodicals devoted to stereo components. Search for articles that discuss the various available features of the two components in which you are interested, and check the same periodicals for equipment reviews of cassette decks and turntables that have appeared in recent months. Audio's Annual Equipment Directory, published every year in October, should be particularly helpful in this regard, and you can write to us again or to the maker if you need specific data.

(adapted from Audio magazine, May 1982; HERMAN BURSTEIN)

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