Tape Guide (Jan. 1979)

Head Quandry

Q. I took my tape deck to a reliable service shop after noticing a considerable loss of high frequencies. The serviceman said that the most probable solution was to have the worn heads replaced with new ones. However, I have read that some heads can be resurfaced and work just like new. Will such resurfacing restore the original high frequency response?

-Bill Arnold, Glidden, Iowa

A. I am inclined to be a bit doubtful about lapping (resurfacing) the heads.

While the high frequency response of the playback head may be restored, this may only be for a short while unless the gap is fairly deep. It seems, to me, that the best course is to get a new head. Keep in mind that the head which is usually most affected by wear is the playback head ... so it may only be necessary to replace the playback head, assuming that your deck has separate record and playback heads.

Bass Increase

Q. My cassette deck has generally given me good results. Lately, however, some of my tapes have exhibited higher bass output than when I first recorded them. I'm not alone in this problem as a friend of mine with an identical deck has noticed it also. Is this a function of time, tape, or machine?

-Mark Boufford, Cape Canaveral, Fla.

A. It is possible that the gap of the playback head has widened resulting in reduced treble response and, hence, an apparent increase in bass. Dirt may have accumulated on the head, causing poor tape-to-head contact, and therefore, impairment of the treble response.

Deck Connection

Q. I have two tape decks but my amplifier has source and monitor jacks for only one tape deck. Can I use the commonly available Y-connectors for recording on both decks simultaneously without damage to the components? Can I add more Y-connectors if I purchase a third deck?

-David DelVecchio, Whitehall, Pa.

A. Y-connectors may work satisfactorily for two decks without excessive loss of signal level, increase in distortion, or impairment of frequency response. The only way to know is to try, which means a modest investment in Y-connectors.

However, I doubt that you will get satisfactory results with more than two decks. In other words, if you are lucky with two decks, don't press your luck.

If you are not lucky with two decks, you'll need to build or buy a switch box so that you can alternately connect the two decks to your amplifier.

Tape Treble

Q. If I use the 1 mil tape there seems to be no noticeable signal loss, but if I use the 12 mil tape of the same brand I lose volume. Also the 12 mil tape seems to have a better high-frequency response. Can you explain this?

-George Woodard, Seattle, Wash.

A. The thinner (1/2 mil) tape has a thinner magnetic coating so that the recorded signal is, therefore, of smaller magnitude. The reason for the better treble response with the ' mil tape is that with the magnetic coating being thinner, the middle and low frequencies are recorded at a lower level, whereas the treble frequencies are less affected by the thinner coating as they tend to be recorded nearer the surface of the tape, thus treble is emphasized relative to the other frequencies. Further, the thinner tape is more limp and, therefore, conforms better to the shape of the playback head, preserving close tape-to-head contact and better treble response.

Noise Problems

Q. I tape phonograph records using an open-reel deck and an external Dolby N/R unit. My problem is excessive tape noise. How does this happen?

-Bill Westheimer, Schnectady, N.Y.

A. The records which you are taping may have excessive noise to begin with and the Dolby system cannot remedy this. The Dolby recording level may be improperly set. You may be recording at too low a level owing to mis-calibration of the deck's VU meters with respect to the tape you're using.

It is also possible that you may have picked up noise owing to a magnetized head or other magnetized parts (guides, etc.) contacted by the tape.

Tape Wear

Q. What are the negative effects of tape wear on the quality of music reproduction? Does tape used in an open-reel deck at 7 1/2 ips wear faster than tape used at 1 7/8 ips in a cassette deck?

- Allen Moore, Stanford, Calif.

A. The chief effect of, tape wear appears to be a loss of the highs. Such loss occurs, principally, during the first five times or so that a recorded tape is played. At high speeds (7 1/2 ips) this effect is negligible, occurring beyond the audible range. At slow speeds (1 7/8 ips)

this effect can be appreciable, reducing response by 6 dB or even more at 15 kHz. The extent of this loss depends upon the oxide formulation ... some oxides may exhibit a loss of only 2 dB, while others may exhibit even greater losses.

Head Explanation

Q. I need an explanation of the cross-field head system. Terrence McQueen, APO San Francisco A. The cross-field head is an extra head mounted opposite the record head which contacts the base side of the tape. Its purpose is to supply bias in a manner that reduces the erasing effect of bias, thereby permitting improved treble response, along with the maintenance of low distortion and high signal-to-noise ratio.

If you have a problem or question on tape recording, write to Mr. Herman Burstein at AUDIO, 401 N. Broad Street, Philadelphia, PA 19108. All letters are answered. Please enclose a stamped, self-addressed envelope.

(Source: Audio magazine, Jan. 1979; Herman Burstein )

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