Tape Guide (Mar. 1982)

Stacking the Decks

Q. My integrated amplifier has provision for two tape decks. I would like to use an open-reel deck in addition to my present phono cartridge and cassette decks, but I detest the job of swapping my three decks among the two sets of tape jacks. Inasmuch as the amplifier has unused preamp-out/main-in jacks, may I successfully use these jacks for the third deck?

-Henry Stafford, Jr., Cincinnati, Ohio

A. If the third deck has provision for routing the incoming signal straight through (from deck input to deck output) when the deck is not in use, you could use the preamp-out/main-in jacks for this unit. Otherwise, all other signal sources will be cut off from the power amplifier section. Also, the deck so connected will be subject to the volume and tone controls and other signal processing elements of the preamp section when recording, but it will not have the benefit of these elements in playback. I think a better solution would be to purchase a tape switching device that permits two or more tape decks to be connected to one set of tape jacks.

Recording Levels

Q. I am aware that high-frequency response tends to improve as record level is reduced when using a cassette deck.

Is it necessary to reduce the record level to the neighborhood of-10 to-20 dB, thus adversely affecting the signal-to noise ratio, in order to maintain high-end frequency response? Or are the high frequencies generally at a low enough level in relationship to the other frequencies so that one can record at about the 0-dB level without affecting high-end response?

-Tom Irwin, Davis, Cal.

A. Rephrasing your own statement, musical material above 1,000 Hz or so typically declines in amplitude to an ex tent sufficient to compensate for the growing inability of the tape system--at low tape speed --to cope with high level signals as frequency increases.

This inability to cope is due to the treble boost required in recording. The lower the tape speed, the greater the treble boost required. Therefore, a problem which is slight at 7 1/2 ips and nonexistent at 15 ips becomes a considerable problem at 1 7/8 ips.

If the record level indicator of your cassette deck is peak reading, ordinarily you should be able to record safely (maintain extended treble response along with low distortion and high signal to-noise ratio) at or about the 0-dB level.

If the indicator is average reading, it will have been calibrated by the manufacturer (assuming good quality control in the plant) to make allowance for high-magnitude transients that might otherwise be over-recorded --with consequent distortion and treble loss. Typically, such a meter reads 0 dB when the signal is about 8 dB below a level producing 3% harmonic distortion. If you are recording off the air or from a disc, you can probably record near the 0-dB level. But if you are recording live,. particularly material with strong transients (such as guitar), you may find it necessary to back down on the recording level about 5 to 10 dB in order to avoid obvious distortion.

Reversing the Aging Process

Q. I've heard that tapes start to deteriorate after the first few plays. Is this true? What can I do to prevent or slow down this process?

-Mike O'Leary, Waialua, Hawaii

A. During the first few plays of a tape, there tends to be a loss of a few dB in the upper frequencies. At the higher tape speeds these losses tend to occur at frequencies far above the normal range of human hearing. At lower speeds, however, particularly at 1 7/8 ips or less, these losses may occur within hearing range. On the other hand, continuing improvements in tapes tend to make such losses quite small, and per haps insignificant, even at speeds as low as 1 7/8 ips. Choice of tape is one of your recourses. Another is to regularly clean the tape heads so as to remove tape oxide that can form a barrier between the heads and the tape, thereby impairing treble response.

Souvenirs from The Sixties

Q. I have several reels of tape bought in 1966. Some are virtually unused. I have just purchased an open-reel deck and hesitate to use this tape if it may damage the heads. I would also like to ask about prerecorded tapes that I bought between 1966 and 1968. Do you think these could damage the heads of my new deck?

-Raymond Disbrow, Belleville, N.J.

A. I very much doubt that use of your old tapes will in any way harm your tape deck. The only possible reason for not using the old tapes has to do with their suitability for recording on modern tape decks. These decks generally provide greater bias than was required by the old tapes; the result would be a drop in treble response. However, this drop might not be an audible one or, if audible, would not necessarily be so gross as to produce displeasure.

With respect to your prerecorded tapes, or tapes that you recorded, there is no problem in playback. Bias does not enter the picture in playback, and play back equalization standards haven't changed. Therefore, such tapes should play back perfectly well, assuming that both the deck on which the tapes were made and your new deck have correct azimuth adjustment and that the old tapes were in the correct quarter-track stereo format.

Speaker Rumblings

Q. After using my cassette deck for a year, I have begun to notice a slight rumble which is audible through my speaker, even without a cassette in the deck. Could you give me a reason for this?

- Neil Nagai, APO Mich.

A. I suspect that the problem lies in the playback electronics of your tape deck; a faulty resistor, capacitor, or transistor could be responsible. It is also possible that the problem is in the power supply; a likely culprit is the filter capacitor(s). You will require the help of an authorized service station.

Angle Angst

Q. I notice that my cassette deck loads the cassette at an angle of about 3° rather than loading it parallel with the front of the deck. Does this affect the deck or the sound?

-Tracy Ching, Sacramento, Cal.

A. I doubt it. Even though the cassette is not parallel with the front of the deck, what counts is whether it is in proper position with respect to the transport mechanism. Generally, these mechanisms will not operate unless the cassette is in correct alignment. To alleviate your concern, you might visit your local audio store to see whether other decks of the same model have the same or similar offset. However, if these other decks appear to have parallel alignment, it may be best to have your unit checked.

Life in the Fast Lane

Q. I own two open-reel decks which frequently use with 10½-inch reels. At times it is necessary to use the fast rewind mode in order to locate a desired point in the recording. However, I am un happy with the excessively fast rewind speed and would like to reduce this by about half. I have been thinking of using a rheostat during the fast rewind mode to reduce voltage and thus reduce the speed. But would this damage the motor or other components?

-Anthony Benson, Pacifica, Cal.

A. I am somewhat dubious about your method of reducing the rewind speed.

Operating a motor at substantially reduced voltage could be harmful unless the motor is designed to be operated in this manner. Another possible problem is that at reduced speed you might not get as smooth a wind of the tape onto the reel.

By far the best course is to seek an answer from the manufacturer of you deck. They know the machine better than anyone else and can suggest a proper solution to the problem of reducing its rewind speed.

Consider the Source

Q. When making a tape, would you recommend equalizing (if necessary) during recording, or recording flat? If you equalize during recording, should the tape be played back flat?

-Bob Hoff man, Worth, Ill.

A. Equalize in recording only if you believe that frequency response of the source is incorrect. If you do equalize in recording, try to avoid excessive treble emphasis, because this increases the risk of tape saturation. If a good deal of treble must be added, it may be wise to add part of this in playback (although this raises the hiss level). Once you have recorded a tape in such a manner that you believe response abnormalities have been fully corrected, the tape should be played back "flat" --meaning that only standard playback equalization is supplied --unless you want to compensate for a response error in the playback sys tem (such as dull-sounding speakers).

(adapted from Audio magazine, Mar. 1982; HERMAN BURSTEIN)

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