AUDIOCLINIC (Jun. 1990)

Loss of Phono Output

Q. I have a problem with my turntable. Recently, between records, the sound disappeared. When I turned the volume way up, I could hear very faint sound. Does this suggest what the problem may be? The rest of my system works fine. Could the phono button on my receiver be defective? The stylus is new, and the cartridge leads look fine and are snugly connected to their terminals. No, I didn't have the tape monitor button pressed on my receiver.

-H. Moski; Branford, Conn.

A. Any number of things could have gone wrong.

If your turntable mutes between records, it is possible that the contacts which short the cartridge output during this time are not reopening. You will have to examine the mechanism to see how the muting is accomplished. A "follower" may have become distorted in some way, preventing it from riding on the cam that normally forces the muting contacts apart during play.

Yes, the phono switch on your receiver could be defective. It's also possible that its contacts could be dirty, but I think this is not the case when both channels have failed at the same time. If dirt were the problem, one channel would probably still play properly, or you might hear distortion rather than silence from one or both channels. Contact cleaning sprays are available for cleaning dirty or oxidized contacts, however. Perhaps an IC common to both phonograph channels has failed. If you can obtain a second receiver/ integrated amplifier, connect the turntable to it and see if your records play normally. If they do, you will know that nothing is wrong with the turntable. If you are greeted with silence, the turntable needs repair.

Audio Quality and Wall Plug Polarity

Q. My question concerns some very subtle and yet musically significant changes that I perceive when I reverse the power-line plug of either my tube or my solid-state amplifier. With a certain polarity, the sound quality appears to be better focused and have better depth, imagery, and transparency than when the plug is inserted with the opposite orientation. A few "reversals" will usually indicate to me which is the preferred one. Is there a scientific explanation of this phenomenon?

-John J. Serocki; Rolling Meadows, Ill.

A. I can't imagine why or how reversing the polarity of the wall plug will bring about sonic differences. About all I can suggest is that perhaps there is a slight background hum with the plug polarized in a certain direction; when the plug is reversed, the hum disappears. The hum might not have been noticeable, yet with it gone, you might hear a more open sound. Such a small amount of hum probably could mask some of the subtler elements of the music.

Poor VCR Audio Performance

Q. I recently purchased a receiver which included surround sound as well as phantom stereo. The sound is fantastic! Well, mostly. When I use either the VCR or cable TV, I lose a great deal of highs and deep bass. I tried the phantom mode, and the same thing occurs. Is there any way to obtain the same response from a VCR or from cable as I do from other program sources?

-John Tallarico; Staten Island, N.Y.

A. The average VCR tends to be deficient in deep bass. Treble is also a problem, especially when it is operated at low tape speed. A Beta Hi-Fi or VHS Hi-Fi machine will solve these problems so long as the audio on the tapes you play is recorded using the Hi-Fi format rather than the standard, longitudinal track.

All too often, TV sources tend not to have a really wide frequency response. If you record from such sources--even with the best available recorder--the audio performance is likely to be less than fulfilling. If the audio is not acceptable to start with, phantom stereo won't improve it.

Some improvement is possible by using a graphic equalizer. You may, however, begin to hear buzz and hiss if the highs are boosted too much; hum may be a problem at times if bass is boosted significantly. Experiment.

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(Source: Audio magazine, Jun. 1990, JOSEPH GIOVANELLI)

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