Tape Guide (Dec. 1981)

Tape Type-Casting

Q. I would like you to explain the differences between tapes denominated as Normal, CrO2 and FeCr with respect to quality of sound reproduction.

-Marc Weingarten, Havertown, Pa.

A. Reviews of cassette tapes by Audio in the recent past (e.g. "The New Cassettes: Performance Update," September 1981) indicate that it is difficult to make any generalizations as to which type of tape is best with respect to frequency response, noise and distortion or with respect to overall performance. The differences in performance seem to be greater between brands than between types of tape (assuming we are talking only about the three types you named and not about cobalt-modified or metal-particle tape).

Where the tape types differ is in terms not of performance but of "adjustments" required to achieve the performance of which they are capable. The Normal (ferric oxide) tapes require some what less bias current than the others. In playback, different playback equalization (more bass boost) is suited to the CrO2 and FeCr tapes than to the ferric oxide tapes.

Period of Adjustment

Q. I own a new open-reel tape deck.

Should I have it adjusted to the tape I select even though the deck has both a bias and equalization selector for both standard and low-noise tape?

-Joseph Van Valen, Los Angeles, Cal.

A. If, after experimenting with various settings of bias and equalization, you find that you can record a tape so that it is a faithful copy of a source such as a phono disc, I see no need to have your deck adjusted.

Purchasing Priorities

Q. I am planning to buy a cassette deck that costs $600, but I see that other companies have come out with the same type of deck for a much more reasonable price. I wonder if I should stick with my original choice or purchase one of the others, although I can afford to buy the $600 unit.

- Juan Placenid, Kansas City, Mo.

A. What you get for your money isn't always immediately visible. What you might be getting for more money includes such things as better construction and design (so that the equipment is freer from maintenance and service problems), better performance (such as flatter and more extended frequency response, lower noise, and lower distortion), closer adherence to specifications, a better warranty or one that is backed up more fully, etc.

"Y" Two Decks

O. My amplifier has connections for two tape decks, but I want to add a third for dubbing purposes. Can I use Y-connectors to hook up two of the decks to the same jacks? Will this cause a de crease in performance or damage?

- James Lamparter, Washington Boro, Pa.

A. Using Y-connectors is unlikely to do any physical or electrical harm. How ever, they may impair performance in terms of frequency response or distortion level.

A better course would be to purchase an external tape switch box, available at fairly reasonable cost. Such a device, for example, can accommodate three decks one to either or both of the others. Some tape switches can accommodate more than three decks, but of course they also cost more. These devices are connected be tween the tape-in and tape-out jacks of an audio system's preamp or receiver.

Unequal Footings

Q. I recently bought some 10 1/2-inch reels containing 3600 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 7200-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 7200-foot tapes.

Transportation Aid

Q. I have a tape transport which I use for playback. I used to feed it into a preamp which supplied tape playback equalization and amplification, but I re placed the preamp with a receiver which doesn't accept signals directly from a tape head. What, if anything, can I do so that I can continue to use my tape transport?

- R.E. Lemmel, Irving, Tex.

A. Some audio stores carry inexpensive tape head equalizer-amplifier units.

Such a unit is often intended for use with either a phono pickup or a tape head, with a switch to choose between the two. The output of the tape head would be fed into this device, and the output of the latter would be fed into a high-level input of your receiver--such as one marked AUX or tape input. If you cannot find such a unit in your local audio stores, try the large mail-order audio houses. It typically costs under $50.00.

If your search is unsuccessful, you might be able to get reasonably satisfactory results by feeding the tape head signal into the phone input and tailoring the signal with bass boost and treble cut.

Volume Views

Q. I recently purchased a cassette deck and asked my dealer for instructions on making tape recordings because the manual is of little help. The manual says to adjust the recording volume so that the meter does not go over 0. The dealer says the very loudest portion of music should just reach but not go over 0. Some hi-fi buffs say the meter should go past 0, to 3 or more, during the loudest portions of the music. The deck manufacturer's sales office says that I can do it either way, that there is no distortion with my deck until the meter goes past 3. Please tell me which is the proper method.

-H. Ellinson, Delta, B.C., Canada

A. There is no absolute answer to your question because it depends on what tape you are using. For a given level of distortion on the tape, some brands or types of tape can accept a higher input level than others. My own inclination would be to follow the manual's instructions and not go above 0 VU.

At worst, you would be losing only 3 dB of signal-to-noise ratio. Inasmuch as your deck probably has something like 65 dB of S/N ratio in the Dolby mode, the loss of 3 dB in S/N should not be troublesome unless you play your sys tem at extremely loud levels.

On the other hand, if you do want to hold on to every possible dB of S/N ratio, buy some high-quality tapes and try recording at levels up to 3 on the meter.

If your ears detect no increase in distortion or deterioration in treble response, then going up to 3 dB is validated for the tape in question.

Strength in Decks

Q. I have a problem with one of two cassette decks connected to my receiver. In playback, it produces a much higher volume level than the other, and I'm afraid of damage to my speakers. Its out put is rated at 1V, whereas the output of the other deck is rated at 410 mV. Could this be the reason?

- Robert Macheska, Ransom, Pa.

A. The difference between the rated output levels of your two decks is 7.7 dB, which does not represent that great an audible difference, It takes about a 10-dB difference for one source to seem twice as loud as another. Therefore, based on rated output, one deck should appear only moderately louder than the other.

Have you switched the two decks at the input to your receiver? It is possible that the receiver has a different gain for each input.

Of course, it is also possible that one of the two is at fault, providing a good deal more or less than the rated output.

Although this doesn't seem very likely, if such is the case, it would not be difficult for an authorized service station to change the output signal to the customary level of about 0.5-V maximum.

Signal Affections

Q. Do the volume or tone controls of a receiver have an effect on the signal being recorded by a tape deck?

-Dwight Gaines, Cleveland, Ohio

A. In the great majority of receivers (and preamplifiers), the signal fed to the tape deck is unaffected by the tone and volume controls. In a few cases, though, the user is given the option of taking the signal from a point after the tone controls. In no case that I know of is this signal taken from a point after the volume control.

Tape Scrape

Q. I enjoyed playing metal tapes with my cassette deck until I was told that this could harm the tape heads. What do you think?

-J.C. Spencer, Wilson, N.C.

A. Thus far I have heard nothing to the effect that metal-particle tapes are more abrasive than other kinds of tape.

Spec Skeptic

Q. What gives with frequency response in cassette decks? Recently as claimed 20 Hz to 18 kHz response of cassette decks is measured at -20 dB, a level I may not hear and also a level that the VU meter or LED indicator of my deck may not even register. What good does this type of measurement do for consumers? Why don't they measure frequency response at typical recording levels, such as 0 dB?

- Con Schieder, Delta, B.C., Canada

A. Yes, cassette frequency response is typically measured at a level 20 dB below the level that produces about 3 percent harmonic distortion for a frequency of about 400 Hz. But most of the music that you hear is down this low or lower, so that it makes a good deal of sense to measure at this level, even though your meter may not make you fully aware of this. (Incidentally, some meters or other indicators do go down to -30 dB or even -40 dB, and then you can see a good deal happening.) Only occasional peaks get up in the vicinity of 0 dB, and it is at this level that distortion threatens to become disturbing. Measurement at the 0-dB level, which corresponds to a minor portion of what we hear, would show treble response ex tending essentially flat to about 8,000 or 10,000 Hz for all but metal-particle tapes. In sum, the way that frequency response is measured, while not perfect, makes good sense.

(Adapted from: Audio magazine, Dec. 1981; Herman Burstein )

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