Tape Guide (May 1978)

Dolby Addition

Q. I have a Sony tape deck which I like very much, except that I have a severe signal-to-noise problem with it. I have been thinking about buying a new deck in the $500.00 range. On the other hand, I was wondering whether I can use a Dolby noise reduction system with my present deck?

Philip Semeca, Astoria, N.Y.

A. The Dolby units can achieve appreciable noise reduction, particularly when used with tape machines producing a good deal of noise. However, you might find that by the time you add the cost of a good Dolby unit to your system, you haven't spent much less than if you had bought a top-flight deck to begin with.

Tone Controls in Recording

Q. Why don't the tone controls affect my tape deck while recording? Can the circuit be changed so these controls can be used?

-Aaron Holley, Pacifica, Calif.

A. A receiver or amplifier is so constructed that the feed to the input of tape recorders connected to it occurs at a point in the circuit before the volume and tone controls, consequently these controls cannot affect the recording.

The output of the recorder, however, feeds into the equipment just before the volume and tone controls, thus the playback has both the volume and tone controls available for use by the listener. The idea behind this is that the listener should make tape recordings which are flat, and any alterations to the sound of these tapes should be made during playback only.

The simplest way by which one can alter the frequency response prior to taping is to introduce a graphic equalizer between the amplifier Tape Out jacks and the input of the recorder.

Minimizing Print-Through

Q. Some time ago you stated that one can minimize print-through by not recording at excessively high levels and by rewinding the tape prior to playing it. I was under the impression that the higher the recording level, then the lower the background noise of the tape.

Could you please enlighten me on this point?

-Michael Cinelli, Scarsdale, N.Y.

A. Recording at a high level results in a high ratio between the audio signal and noise due to the tape and tape machine electronics. Also, a high level signal on the tape tends to magnetize the adjacent layers of tape on the reel which results in a low ratio between the audio signal and the print through signal (sound of the adjacent layers).

Recorder Mike Matching

Q. I own a Roberts 17258L reel and cartridge recorder, and when I wanted better microphones I purchased the Sony ECM198 condenser microphones.

After purchasing them I found out that my set calls for high-impedance mikes, whereas the Sony ones are low impedance. Somebody suggested that I buy preamps which I did. Am I getting full benefit out of the microphones with the use of the preamp?

-Charles Keoseian, Fitchburg, Mass.

A. To adapt a low-impedance microphone to a high-impedance input, one customarily uses a matching transformer, which can either be obtained from the microphone manufacturer or he can recommend one. You can also use a preamp of the type made for phono pickups and tape heads, but this may require removal of the equalization network for phono and tape, or the unit may have a switch for bypassing the equalization circuit so it can be used with the microphone.

However, the preamp may add appreciable noise and is not a desirable way of matching a low-impedance mike to a high-impedance input.

If you have a problem or question on tape recording, write to Mr. Herman Burstein al AUDIO, 401 North Broad Street, Philadelphia, Pa. 19108. All letters are answered.

Please enclose a stamped, sell-addressed envelope.

(Source: Audio magazine, May 1978; by Herman Burstein)

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