TAPE GUIDE (Jul. 1992)

The Cons of HX Pro

In recent years a number of "Tape Guide" readers have inquired whether they are missing something important if their decks lack HX Pro. This has brought up the question why Nakamichi still eschews it; the company is perhaps just about the only manufacturer of high-quality decks not to use it.

My answer has been that there is more than one design path to desired results, and that HX Pro might introduce not only the benefit of extended treble at high signal levels but also the disadvantage of inaccurate variations in bias; such variations could increase distortion and roll off flatness of response at the high end of the audio spectrum.

When I asked, Nakamichi stated that they've chosen to overcome the cassette format's headroom limitations by designing and making their own heads, electronics, and transport mechanisms rather than by adding circuits such as HX Pro. According to Technical Support Coordinator Hyam R. Sosnow, the headroom of Nakamichi's discrete three-head decks has exceeded that of "virtually every other make and model of cassette deck, even those incorporating HX Pro. . ." He continues: "Unless a deck incorporating HX Pro has been very carefully adjusted for the particular tape formulation being used, the resulting inaccurate variations in bias can actually re duce high-frequency headroom over what the same deck could achieve if HX Pro were not used. Many decks incorporating HX Pro lack the user-calibration facilities for record sensitivity that are essential to its proper operation.... Nakamichi would not consider building [a two-head deck with HX Pro] without including the user-calibration facilities necessary to maximize its performance. The resulting two-head deck would be [nearly as expensive as] our least expensive discrete three-head deck yet would not equal the performance of the three-head model."

VCR for Audio

Q. Is it a good idea to use a VCR instead of a high-quality analog cassette deck? In my case, cassette size is unimportant, but uninterrupted recording is important inasmuch as classical music often spans more than 50 minutes [one side of a C-100 cassette; a C-120, which offers 60 minutes per side, is not recommended for high-quality results. - H.B.]. Please advise on the pros and cons of using a VCR for high-quality audio recording, and such considerations as to what Dolby NR system is employed and whether or not metal tape is required.

-M. Grant, Gardena, Cal.

A. My own experience and reports from a number of readers indicate that very good audio recordings can be made with a Hi-Fi VCR. Repeat: With a Hi-Fi VCR. In terms of signal-to-noise ratio, frequency response, distortion, and motion (low wow and flutter and accurate speed), a good Hi-Fi VCR can outperform the best of analog cassette decks. Using 1-120 videotape at the slowest VCR speed, you can get six hours of recording without interruption. I and others have found little, if any, audible difference between audio recording at the fastest and slowest VCR speeds.

The only important disadvantage I can think of in using a VCR for recording music is that you cannot monitor the tape while it is being recorded, something that can be done when re cording with a three-head cassette deck. That is, you cannot simultaneously record and play in order to make certain that the recording is proceeding to your satisfaction.

For Hi-Fi recording, the VCR does not use Dolby noise reduction. How ever, linear recording, which is per formed along the edge of the tape by both conventional and Hi-Fi VCRs in a manner comparable to that of an analog cassette deck, does sometimes employ Dolby noise reduction. Whether in a Hi-Fi VCR or in a conventional one, the quality of linear recording is substantially lower than that of Hi-Fi recording, which makes use of frequency modulation.

So far as I know, videotapes all em ploy a ferric-oxide coating, which is more or less similar to the coating on Type I analog cassette tapes; that is, metal tape is not used. While you should use good-quality videotape of a reputable manufacturer, you need not go to unusual lengths in this respect. For example, you do not need to purchase one of the special tapes labeled "stereo."

Poor Recording

Q. I have a seven-year-old cassette deck that plays prerecorded music just fine but records poorly. When playing a tape that was just recorded, it exhibits a 5-dB drop relative to the initial recording level, and the left channel is 1 or 2 dB lower than the right one. I have cleaned and demagnetized the heads. And I took the deck to a repair shop but was told nothing is wrong. I'd appreciate some suggestions on what the problem might be.

-Jason Cooper, Miami, Fla.

A. Taking your problems in what seems to be the reverse order of importance, the slight difference be tween left and right channels is rather inconsequential. You can easily adjust in recording or playback for this.

The 5-dB difference between record and playback levels may be due in part to the sensitivity of the tape you are using--that is, the amount of out put for a given input. But it is also possible that it may be due to a fault in the recording circuit.

When you say that the deck records poorly, I assume you mean the quality of sound and not just the level. Possibly, bias is insufficient. If the sound is too high-pitched and distorted (grainy, coarse), this would indicate too little bias. Also, insufficient bias would re duce the recorded level.

If bias isn't the culprit, there are other things that could have gone wrong with the recording circuit of a seven year-old deck. Resistors may have changed value, capacitors may have become leaky and/or changed in value, or transistors may not be performing up to specifications. In this event, you need a service shop that is competent and honorable. If the manufacturer of your deck is still in business, it should be able to supply the names of authorized service shops in your area.

On the other hand, a thorough check and repair can cost a tidy sum, per haps $100. It is probably wiser, to put the money into a new deck. Some very nice performers are now available at relatively moderate prices.

(adapted from Audio magazine, Jul. 1992, HERMAN BURSTEIN)

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