TAPE GUIDE (Sept. 1984)

Automatic Sensitivity Adjustment

Q. My cassette deck has a microprocessor which, according to the manufacturer, automatically sets the bias, equalization, and sensitivity levels. Does this also set the Dolby level?

-William H. White, Fullerton, Cal.

A. Yes. If the deck has been correctly adjusted at the factory with respect to Dolby reference level, the automatic sensitivity adjustment performed by the microprocessor makes any required change, for the particular tape that is being recorded.

Tape sensitivity refers to the amount of signal output delivered by the tape for a given signal input to it. For the Dolby noise-reduction system to work properly, the level of the signal presented to the encoding (treble-boost) system must match the level presented to the decoding (complementary treble-cut) system. If a tape has high sensitivity, which signifies a relatively high signal output-or a lower signal input required for a given signal output--allowance for this must be made in recording; the signal output in playback will thereby match the signal input in recording.

Belt Source

Q. I own an open-reel tape deck which is about six or seven years old. It is now inoperable because the drive belt has stretched with age. I have tried electronics parts stores and wholesale houses in search of a replacement belt, but it appears that my belt is different enough from anything currently available that nothing will work. I have been told that the manufacturer of my deck has suspended all U.S. operations. Do you know how 1 can get a new belt?

- Al Beckett; Oklahoma City, Okla.

A. Try Projector-Recorder Belt Corp., Department SR, 147 Whitewater St., Whitewater, Wisc. 53190.

Cassette vs. Open-Reel Decks

Q. I am no longer satisfied with my present cassette deck and am trying to decide whether to trade up to a better one or to buy an open-reel deck.

Open-reel looks attractive to me for several reasons: I can buy 10 1/2 inch reels of unspliced tape used only once from a local radio station for only $1.00 apiece. I could record much more material on a (10 1/2-inch) reel even at the high speed of 7 1/2 ips. I am concerned with the limits of dynamic range of cassette, inasmuch as phono records are improving and my collection contains more and more discs made from digital and half-speed masters. I would like your opinion on cassette versus open-reel.

-Chris Sellers; Ames, Iowa

A. As cassette decks and tapes have steadily improved, it has become increasingly difficult for most persons to detect a significant difference between a fine cassette unit and a fine open-reel one. Metal-particle (Type IV) tape has further decreased the difference; at the same time, improvements in the kinds tape-ferric oxide other of (Type I), chromium dioxide or ferricobalt (Type II), and ferrichrome (Type III)-have left them a scant distance behind metal tape. Important increases in signal-to-noise ratio-owing chiefly to dbx (about 30 dB) and Dolby C (about 20 dB) noise reduction-have made cassette a truly high-fidelity medium. Such improvements permit the recordist to sacrifice a few dB of S/N by recording at a slightly lower level, thereby avoiding tape saturation and consequent distortion and loss of high treble.

The consensus seems to be that unless you're directly taping live material, you can do about as well with cassette as with open-reel. On the other hand, the advent of improved recorded material, in particular the Compact Disc, presents a new challenge to tape recording, so that the superiority of open-reel, particularly at speeds of 7 1/2 and 15 ips, may again become evident-at least for a while, until cassette catches up again.

As you recognize, open-reel, particularly if you have a deck that takes 10 1/2-inch reels (some cannot accept reels larger than 7 inches), will afford you longer recording and playback time per reel. Further, editing is easier with open-reel than with cassette.

Perhaps the most audible inferiority of cassette with respect to open-reel, particularly if open-reel is operated at 7 1/2 ips or more, lies in the area of azimuth alignment. The faster speed of open-reel causes a given degree of azimuth misalignment to have less adverse effect on treble response. True, the wider track of open-reel is disadvantageous with respect to the azimuth problem, but this disadvantage is substantially overcome by the faster speed. On the other hand, cassette deck manufacturers-at least those making quality units-are paying closer and more effective attention to accurate azimuth alignment.

In view of all the factors you have mentioned, I slightly incline toward open-reel in your particular case. But I think you should do some careful listening to both cassette and open-reel decks before you make your decision.

Service Problem

Q. About two months ago I took my open-reel tape deck to be cleaned and serviced. When it came back it was worse than it had ever been; it wouldn't run in fast forward and it wouldn't rewind without spilling tape all over the place; in operating mode it would drag as it came to the end of a reel. When I brought in the deck, the only problem was the drag. I wish to take my deck back, but I am afraid that the shop may mess it up even more. Where can I get my deck fixed properly?

-George Pruitt, Pemberton, N.J.

A. The Tape Guide cannot recommend specific service shops. Try to obtain the name of an authorized ser vice shop in your area from the deck manufacturer, from a local audio dealer, or from the yellow pages of your telephone book.

Whatever service shop you decide on, be sure to do two things: (1) Demonstrate the problem you have so that you and the shop agree as to what it is, and so that it is clear that all else is working well. (2) When you pick up the deck, have the shop demonstrate that the problem has been fixed and that all else is working properly. Service shops are not always eager to do so, but unless they are you probably shouldn't engage their services.

If a great deal of time hasn't passed since your deck was serviced, I think you might give that service shop a chance to correct its work, provided it is willing to do so at no or minimal cost to you.

(Source: Audio magazine, Sept. 1984, HERMAN BURSTEIN)

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