Tape Guide (Q and A) (May 1974)

Radio Interference

Q. I own a KLH model 11-W stereo module and a Sony 105 tape recorder.

When I tried to copy records, I found that I was picking up shortwave broadcasts from a “gypsy" cab office down the street. My cable assembly was two phono plugs to one phono jack y adapter to a mini-jack input/phono plug output adapter to a miniplug cable. I also pick up radio broadcasts when I listen to the tape recorder with headphones, using a stereo phone jack to a miniplug adapter., but I only seem to pick it up off the external speaker jack, not the monitor jack. If there is a not too technically complicated way of filtering out the broadcasts it would be a great help.

-Fred M. Schiller, Brooklyn, N.Y.

A. Your type of problem often presents a great deal of difficulty, particularly when the interfering signal is strong. The usual simple solution is to introduce a small capacitor, of a few pFd, between input and ground at the first amplification stage. If this is beyond your ability, you should consult your audio dealer as to whether he has some kind of trap or filter that can be used between your tape recorder and the rest of your audio system. If he does, try to get it on a trial basis in case it doesn't work.

I strongly suggest that you eliminate your complicated system of plugs, jacks, adapters, and cables; use instead one simple cable between the tape deck and the receiver. And use as short a cable as possible. Rectification of the undesired signal may be occurring as the result of imperfect contacts among your plugs, jacks, etc.

Hook-up for TV

Q. After recording from my RCA portable black and white TV, I get a terrible buzz when playing back the tape. My TV has no outlets in the back for a tape recorder. I've tried putting my microphone farther away from the TV, but this hasn't helped too much. Could you give me some advice on what to do to reduce this buzz?

-Elizabeth Kaponya; Brighton, Massachusetts

A. Perhaps you can reduce the TV buzz by carefully adjusting the fine tuning knob after you select a station. Adjust the knob for minimum buzz with an acceptable picture. It may also be that your microphone is particularly sensitive in the range of the buzz frequency and exaggerates this frequency.

You may get less buzz--and doubtless you will get better overall sound--if you do not feed your tape recorder through a microphone in order to record TV sound. Instead, connect your tape recorder directly to the TV. One way is to connect a cable from the two speaker leads of the TV to the high-level input of your tape recorder. Such cables are sold in audio stores. One end comes with alligator clips for connection to the speaker's leads; the other end has a plug for connection to your tape recorder. The preferable but more difficult way of making the connection is to place the TV side of the cable across the hot and ground terminals of your TV set's volume control. However, unless your TV has an isolating power transformer, do not use the second form of connection. In fact, unless your TV has such a transformer, the first type of connection I described may also present a shock danger; this depends on whether either speaker lead is grounded; if neither lead is grounded, there is no danger.

Reducing Hiss

Q. I have been using a Sony TC-355 deck for quite a while for echo effects on guitar. Is there some type of filter I could build or buy to stop hiss or fried eggs noise when treble boost is applied during playback? How long would you recommend using a tape?

-Francis Miller; Duluth, Minnesota

A. Your first question is somewhat contradictory, because treble boost accentuates the hiss you want to reduce.

If your concern is with noise generated by the tape recorder system, rather than by other components, you should investigate the Dolby B noise reduction system. The life span of a tape depends on its quality. Generally, a tape of good quality should be serviceable for several hundred plays, and quite possibly for 1,000 or even more.

(Audio magazine, May 1974; Herman Burstein)

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