Tape Guide (Q and A) (Jul 1970)

Sound On Sound

Q. Is it possible to install sound on sound in a tape recorder that doesn't have this feature, either by an internal connection or an external device?

-Jeffrey Cripps, Webster, N.Y.

A. The requirement for sound on sound is that you be able to record on one track (say Track 3) while playing back another track (say Track 1); also that you be able to mix two signals to be recorded on Track 3--the signal being played back on Track 1 and a new signal; and that you be able to monitor the Track 1 playback in order to synchronize the new signal you are adding to it. All this is not very simple, and if your machine doesn't already provide for sound on sound, it would take a fair amount of work to convert your machine.

Tape Head Input

Q. I have been interested in purchasing a tape transport to feed into the tape-head input of my audio system preamp. This purchase poses several problems. (1) There are almost no manufacturers of tape transports (sans electronics); then why do nearly all amplifiers and preamps have a tape head input? (2) I understand there are problems associated with equalization of playback-head output, especially in the bass. Is there any way to remove the peaked response in the bass without recourse to the playback electronics, or without having to have a playback amplifier? (3) I assume that most of the differences between 7.5-ips and 3.75-ips playback equalization can he compensated by the tone controls of my audio system amplifier. Is this true?

-John R. Bates, Philadelphia, Pa.

A. (1) The tape-head input seems to be something of a relic, like the human appendix.

2. As the horizontal dimension of the playback head approaches the size of a recorded wavelength (which happens in the bass region) , the entire head and not merely the gap tends to react to the magnetic flux on the tape, thereby augmenting bass response. I do not know of a way of eliminating this except to make an extremely large head.

3. If by "most" you mean most and not all, then it is fairly true that "most of the differences between 7.5and 3.75-ips playback equalization can be compensated by the tone controls." If you are using 7.5-ips equalization to play a 3.75-ips tape, you would supply some bass cut and some treble boost.

Quarter- vs. Half-Track

Q. Which is better--half-track or quarter-track--for stereo operation?

(Lee C. Stauffer, Los Angeles, California)

A. In today's state of the art, nearly as good performance can be achieved with quarter-track as with half-track. However, signal-to-noise ratio is somewhat better with half-track. On the other hand, correct azimuth alignment is more critical for half-track. With half-track, there is greater freedom from "left-channel dropout" (lower signal level on the left channel). If you plan to edit your tapes, you cannot do so if tracks have been recorded in two directions; hence for stereo you would want half-track operation (recording in one direction only).

Tape Storage

Q. Can tapes be stored in steel cans to shield them from the earth's and other magnetic fields, or would the can become magnetized and thus subject the tapes to a field which would adversely affect them? Is there any way to protect tapes from stray fields during storage?

(R. Hawkins, New York, N.Y.)

A. I doubt that recorded tape is apt to suffer from the earth's magnetic field.

However, it may suffer injury if brought close to powerful motors, transformers, and the like with a magnetic field extending an appreciable distance. Then it becomes meaningful to store the tape in a steel can. Better yet, cans made of a special shielding material are available.

(Audio magazine, Jul. 1970; Herman Burstein)

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