Tape Guide (Q and A) (Jan. 1974)

Records to Tape

Q. I have of late been transferring many of my records onto tape, some at 7 1/2 ips and some at 15 ips. My questions are these: Is it possible that my tape reproduction can sound better than the original record? I notice that at loud volume, playing back the tape in comparison with the record, the tape sounds better! Yet how can one get more than what is on the record? I do notice a slight increase in hiss as I A-B the record and tape at 15 ips, which is puzzling since the hiss is less at 7 1/2 ips. Why is that? Also, I have a Dave Brubeck stereo record, which is much quieter than the prerecorded tape version of this record. Is this the usual case?

-Jeff De Carlo; Demarest, New Jersey

A. If your tape machine has perfectly flat frequency response, then a tape copy cannot in logic sound better than the disc original. On the other hand, if the tape machine deviates somewhat from flat response, in doing so it may reduce some noise frequencies and thereby sound better.

Hiss should be less at 15 ips than at 7 1/2 ips. A possible explanation for your getting less hiss at 7 1/2 ips is a deviation from correct equalization. Another possible explanation is that the hiss you speak of is not from your tape system but is reproduced hiss from the disc. Likely, your tape machine is a more faithful reproducer at 15 ips than at 7 1/2 ips, so that the disc hiss is more faithfully reproduced at the higher speed.

A tape goes through several generations of copying and recopying before it is issued as a prerecorded tape. With each generation, hiss increases. Hence discs often sound better than their tape counterparts. However, use of the Dolby noise reduction system should result in quieter prerecorded tapes.

Cassette Maintenance

Q. Do cassette tape players need to be demagnetized as do tape recorder/ players? Are the cassette tape head cleaners damaging to the tape heads? Is it possible to damage a tape recorder and/or player by demagnetizing and cleaning it too frequently? Do the recorder heads need to be replaced after much use as phono cartridges do? If so, can they be replaced by the consumer, or do they have to be replaced by a serviceman?

-Frank J. Valence, Upper Darby, Pennsylvania

A. Cassette tape players should be regularly demagnetized. Consult the cassette manufacturer as to what may or may not be used for cleaning. I doubt that one can clean and demagnetize excessively in terms of damaging a tape recorder. Yes, heads need replacement. The frequency of replacement depends on the quality of the head. A good head may last about 1,000 to 2,000 hours of use. Claims of much longer life have recently been made for some heads of new material. Heads should be replaced by a qualified technician.

Tape Lubrication

Q. I would appreciate your opinion regarding the use of tape lubrication kits. Do you feel that these are desirable, or that they may be an unnecessary gimmick? Do low-priced tapes and/or white box tapes necessarily require lubrication more than high-priced tapes?

-C. J. Hill; San Francisco, California

A. The advisability of tape lubricating devices depends a good deal on the tape and on the machine you are using. If you have no problem of squeal, then you might not find these devices useful. If you do have a squeal problem, they might help, or they might not. Similar comments apply to oxide shedding. There is the possibility that if the lubricant has not completely dried by the time it reaches the capstan, the capstan may become slippery, resulting in tape slippage and therefore in wow. There is a strong tendency for the higher-priced tapes to be more carefully lubricated than the lower-priced ones. This means not a maximum of lubricant but the optimum amount--enough to move the tape easily past the heads, but little enough so that the capstan grabs the tape firmly.

Loss of High Frequencies

Q. I have a Viking 433 deck. A review of this machine showed a record-playback curve, at 3 3/4 ips, of 40 to 15,000 Hz, within 4 dB, with a rising high end.

This seemed to indicate very good high end response at the slower speed Using Scotch 203 tape, I have sought to optimize bias by recording a 1 kHz signal at 3 3/4 ips and setting bias for maximum output as read in playback on the VU meter. However, instead of my recordings sounding overly-bright, as expected, there is a very definite loss of high frequencies. I have tried under-biasing, but without success. My questions are:

(1) How could I adjust playback equalization for optimum performance with Scotch 203, and do you think it would make a significant difference? (2) On occasion I have pinned my VU meters by some sort of feedback when, while listening to my tape through Koss ESP-7 electrostatic headphones, I pass my hand near the playback head of my deck. Is a feedback loop of this nature possible? Could such levels have magnetized my heads beyond the ability of my demagnetizer to remove it? (3) Is it possible, by feeding different frequencies into the recorder and monitoring their respective playback levels on my VU meters, to get some idea of my recorder's frequency response?

-Bruce Schwartz; Philadelphia, Pa.

A. (1) At 3 3/4 ips, your machine should probably be somewhat under-biased in order to maintain frequency response out to 15,000 Hz. If under-biasing results in dull sound, this suggests something else is wrong, such as a playback head with a worn gap, a magnetized playback head, faulty record equalization, or faulty playback equalization. If tapes recorded on other machines sound satisfactory when played back on yours, then neither the playback head nor playback equalization is at fault. When going from conventional to low-noise tape, the adjustments required are in recording (bias, record equalization, and record drive), not in playback. (2) Your hand is a source of hum, and apparently the playback head picked up enough to pin the meter. Whether this may have magnetized your head beyond redemption is something that I doubt. Have you tried using a bulk eraser to demagnetize the head? (3) Yes, you can get a substantial idea of your recorder's overall response by feeding in various frequencies at a constant level and measuring their playback level on your meter. This assumes you have a true VU meter with substantially flat frequency response. Not all meters found in tape recorders are true VU meters with flat audio response.

(Audio magazine, Jan. 1974; Herman Burstein)

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