Tape Guide (Q and A) (Apr. 1976)

Reel Warp

Q. All of the plastic tape reels I’ve ever used on my TEAC 6010 tape deck tend to warp, and the result is that the tape rubs against the reel. This rubbing sound can be extremely annoying, especially when listening to classical or background music at low levels. I've tried using two different types of metal reels, both of which proved unsatisfactory when the deck was used in fast forward or rewind modes. It appears that the wider metal reels cause the tape to bunch up in a zig-zag fashion, which results in frayed tape edges. Do you have any recommendations?

-Robert C. Armstrong, APO San Francisco, Calif.

A. Aside from trying more of the wide variety of plastic reels on the market, you can very likely solve your warp difficulties by storing your tapes differently. However, from your mention of what's happening with the metal reels, it appears that the tape guides may be out of alignment with the turntable on which the reel sits or that the turntable may not be parallel with the line of tape motion. The rubbing of the tape edge causes a squeal in the case of the plastic reels, while with the metal reels, this friction during high-speed tape. transport simply results in frayed tape edges instead of the rubbing noise.

Use of Head Demagnetizer

Q. I notice in the manual for my TEAC 6010 tape deck that there is a cautionary note concerning possible damage to the VU meters from a head demagnetizer. Therefore, I am reluctant to use a bulk eraser, as has sometimes been recommended. The meters are approximately four inches from the head cover. How close can I get to the meters with a hand-held bulk eraser?

-Floyd Rominsky, Glen Ridge, N.J.

A. I would strongly repeat the advice given in the TEAC manual about keeping bulk erasers a good distance from the meters because the strong field of the eraser might dislocate the windings in the meter. It might even do so in the case of a tape head, depending on construction of the head, though I believe there should be no problem in your case. My best guess is that six inches is about right, but I strongly suggest that you consult TEAC on this.

Causes of Print-Through

Q. I would like to find out about print-through. I have a large collection of tapes 1 recorded, some of which are as much as 10 years old.

Only on one of these have I ever encountered a problem with print through. Yet recently I made a recording on a 1-mil tape at 7 1/2 ips in stereo, and when I played it back 24 hours later, I was dismayed to discover almost continuous background "music." I thought that print-through was a phenomenon of aging, particularly with thinner, cheaper tapes. The brand of tape 1 used is not particularly expensive, but has been reliable, and this individual tape had not bee previously recorded and erased. Would you please explain what causes print-through?

-Barbara Foerster, Chicago, Ill.

A. Print-through increases with level of signal recorded on the tape, oxide formulation of the tape, thinner tapes, and time. In your case, the most likely cause appears to have been the thinness of the tape and quite possibly the signal level and formulation as well. Since the onset of print-through is shortly after the recording is made, if and when it is going to occur, your experiencing of print-through just a day later is usual.

Tape Guide II

FROM TIME to time, as a companion piece to The Tape Guide, we would like to supply ideas to readers who think of tape recording not merely as a passive activity but as one that offers the opportunity to be imaginative and creative.

To do so, we will have to rely greatly on your suggestions. Therefore we shall be happy to hear from you. To get things going, following are four ideas, for better or worse.

-Herman Burstein

Spaciousnes

Record the left and right tracks slightly out of synchronization, by a fraction of a second, and play them back simultaneously. The source can be stereo or mono. If there is a great difference between the left and right channel sounds in stereo, try mixing the channels slightly in recording or in playback. The time lag between the two tracks has to be experimentally determined. If the lag is too small, there will be little if any change in the sound. If the lag is too great, one will hear two distinct sounds. If the lag is about right, the sense of spaciousness will be greatly enhanced.

The equipment used is a recording tape deck and a signal source, which may be either a playback tape deck or a turntable. It is important that the equipment be able to maintain constant speed. Following is the procedure.

1. Record the left channel onto the left track.

2. Rewind the tape and play the left channel. Identify the point on the tape where the sound begins. If the deck has separate record and playback heads, back up (rewind) the tape a distance corresponding to that between the centers of the record and playback heads. Thus, the point where the sound begins is at the record head.

3. Play the right channel. Just as the right channel sound begins, start the record deck, and record on the right track.

4. Play both the left and right channels. If the results are pleasing-a definite increase in spaciousness without double sound-stop there. If the results are unsatisfactory, repeat Steps 2 and 3, this time starting the right channel sound somewhat earlier or later with respect to the left channel. There is no need to repeat Step 1.

Warped Record

A prized 33-1/3 rpm record, un played for a long time, turned out to have acquired an ugly warp. For about the first inch of the outer radius, the warp was so bad as to throw the stylus out of the groove, even when tracking force was greatly increased. It so happened that the turntable in question included the 16-2/3 rpm speed. And the stylus remained in the groove when the record was played at 16-2/3. With the help of a tape deck, the problem was easily solved.

The first inch or so of the record, up to a convenient break in the sound (conclusion of a symphonic movement), was played at 16-2/3 and recorded at 3-3/4 ips on tape. The rest of the record was played at 33-1/3 and recorded at 7-1/2 ips. The result was a tape recording which sounded good throughout when played at 7-1/2 ips; for the first movement, half-speed when playing the record was compensated by double-speed when playing the tape.

Playback of Dolby Encoded FM

Many of us involved in taping off FM, or just plain listening, have FM tuners that provide only the old standard 75 uS de-emphasis. But Dolby encoded broadcasts call for 25 µS de emphasis plus Dolby decoding. What can one do without adding new equipment, such as an adapter that gives one the choice of either 25 or 75µS de-emphasis, as well as a Dolby decoder? Perhaps the following will not satisfy the ultra-finicky, but it may provide an audibly satisfactory answer for many others. Simply feed the FM signal (with 75 µS de-emphasis) into the tape deck without Dolby decoding.

The treble loss due to 75 uS de-emphasis tends to be offset by the treble boost due to lack of Dolby decoding.

The net effect, at least to this writer's ears, is quite satisfactory.

New Tapes with Excessive Treble

New tape formulations sometimes have "hotter" treble response than their predecessors. This may be a boon, helping achieve flatter treble response than formerly. Or it may result in unwanted exaggeration of highs. The proper answer is to adjust bias, but this often presents problems: The adjustment may be an internal one, entailing difficulty of access and of proper setting for the average owner. Even if the bias is adjusted by a competent person, then bias may be right for the new tape but wrong for older tapes that one wishes to record.

An alternative answer is to use the tone controls in playback. A better answer-because it results in less distortion-is to use the tone controls in recording if the receiver or preamp permits the tone controls to be effective for tape recording. Some receivers and preamps (probably a minority) permit this, while other don't.

Another answer is possible for those having a tape deck that supplies Dolby decoding for the incoming signal. An example is the Tandberg 9200XD. Using tape with a new oxide, sound was over-bright. But setting the Tandberg's Dolby switch to the Dolby FM position enabled the frequency response to appear "just about right."

(Audio magazine, Herman Burstein)

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