Tape Guide (Q and A) (Jul. 1973)

by Herman Burstein

A Question of Quality

Q. The boys in the shop have a little problem. Given two tape recorders, both listing for $300, one with a single motor and cross field head, and the other with three motors and no cross field head, which is more desirable? The unit with the cross field head claims response to 20 KHz at 7 1/2 ips, while the other unit claims response to 15 KHz. Please settle the argument.

-Harry Sitkoff, Far Rockaway, N.Y.

A. I am afraid you have asked the following type of question: Is it hotter in the summer or in the country? Do you walk to work or carry your lunch? The fact that one machine has 3 motors while the other has one motor does not necessarily make the 3-motor unit better. What is the quality of the motor(s)? What is the quality of the engineering behind their use? Similarly, the fact that one machine has a cross field head and the other does not, fails in itself to designate which is the better machine. I can well visualize a situation where a tape recorder with one motor and no cross field head is the better of the two owing to better design, better construction, better parts, and better quality control.

Crosstalk and Alignment

Q. A couple of years ago I bought a Uher 24 Special at a closeout price with the thought that it would be a perfect playback deck for use in copying tapes.

It operates all right with the exception that it has a bad lack of channel separation, a problem that gets more annoying all the time. When a quiet passage comes along, one can hear crosstalk from the other two channels if the tape has been recorded in both directions. The recorder is very sensitive to head adjustment changes, and the problem varies from one prerecorded tape to another. A minor adjustment the factory made on the playback head is worthless, and I have fastened the head down solid. I will appreciate any information which might help.

-M. Glen Bair, Idaho Falls, Idaho.

A. You indicate that crosstalk only occurs when the tape is recorded in both directions. This eliminates the electronics as the source of crosstalk and points to the heads. The problem may lie in vertical mis-positioning of the heads. It may lie in the heads themselves; that is, their gaps may be too long (vertically), so that they tend to pick up signal from the adjacent tracks.

It may lie in the tape guides, which permit the tape to weave up and down, so that adjacent channel signals are picked up as the tape weaves.

Quality In Cassettes

Q. I am purchasing blank tape cassettes and have been confronted with a bewildering number of brands sold at a wide range of prices. Many are advertised as low-noise and/or wide-range, and one (Norelco) offers a life-time guarantee.

Are there significant differences between tape brands? In shopping around, TDK and BASF seem to be rated best, with Scotch, Norelco, and some others making the second echelon, and Lafayette, Hitachi, Ampex, and Audiopak trailing.

But these are only salesmen's suggestions. Your opinions on tape quality, taking noise, dynamic range, frequency response, and life expectancy in mind, would be most helpful.

-Gerald Goodman, Brooklyn, N.Y.

A. Generally speaking, the quality of tapes is proportional to the prices paid for them. I cannot make recommendations as to specific brands, for the policy of AUDIO prohibits my doing so. I can say that the low-noise tapes have been finding increasing favor, for they do result in somewhat lower noise along with improved treble response. However, your tape machine has to be properly adjusted to take advantage of these tapes.

Good Recordings

Q. I am using two Electro-Voice RE-20 cardioid and two Neumann U-87 omni-cardioid microphones with the Crown CX822 stereo tape recorder for on-location recording. I would like the following questions answered: (1) Why am I not getting quality recordings from these microphones? (2) Is the Crown CX822 considered a “professional recorder" or should I purchase a Scully or Ampex recorder which I know is considered “professional"?

-Louis Tousana, Jr., Chicago, Illinois.

A. It is difficult to answer your questions about the microphones because I do not know the exact manner in which you are using them, nor the exact problems you are having with them. Is it possible that you are overloading the tape recorder (really the tape) and therefore getting distorted response along with poor treble? In making live recordings, you have to be very careful not to allow the recording level to get too high. It takes skill and experience to properly interpret a VU meter reading and to adjust tape recording level on the basis of the meter and the type of sound.

As for your question about the various brands of tape machines, the policy of AUDIO prohibits me from making comment.

Making Phase Outs

Q. I am trying to achieve a special effect. It is a whirling, swishing sound that effects the total sound where it is used. The sound seems to rise, dip, and then "null out" and start all over again. I have heard this called "re-phasing" and "phasing out." How is this sound produced? Is there a special machine that produces it? I would appreciate your giving me some information on this sound effect.

-Michael Caponera.

A. I cannot refer you to a special machine for "phasing out." Perhaps you can achieve the desired effect with a stereo amplifier with suitable features.

Assume that you feed the same signal to two channels, but out of phase with each other (many stereo amps permit you to reverse the phase of one channel). Next, assume that you can combine the two signals to a varying degree (as many stereo amplifiers enable one to do). Depending upon the setting of the control that governs degree of mixing of the two channels, you will have "phasing out." Varying the setting of the control as you feed the amplifier output into a tape recorder will vary the amount of "phasing out." The mixing control has to be of high quality so that it will not "scratch" (produce noise) as you vary its setting.

(Audio magazine, Jul. 1973; Herman Burstein)

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