Audioclinic (Q and A) (Feb. 1971)

Microphonic Cartridge

Q. When my tonearm is in its rest position, any time I tap the turntable anywhere on its surface, my speakers reproduce this tapping. What causes this problem?

-John Hanley, Woodside, New York.

A. The fact that you hear sound when you tap your phonograph is perfectly normal. Sound vibrations are transmitted from the arm to the cartridge.

Something in the cartridge, perhaps the stylus assembly, is microphonic. In other words, something in the cartridge changes its physical shape or position in such a way as to cause a slight voltage to appear at the output of the cartridge, and you hear this output as a "ping." Some cartridges exhibit this tendency more than others. Any cartridge, however, will produce this strange sound if the volume control is turned up far enough.

Wow and Flutter

Q. What is "wow and flutter"? I understand that these are important factors in selecting equipment. I gather that "wow" is a change in motor speed in both tape decks and turntables but flutter?

-Sgt. Paul Bonney, APO San Francisco, California.

A. "Wow and flutter" refer to speed variations which occur in both turntables and tape recorders. Tape and discs are intended to be driven at a constant speed. It is very difficult to make a piece of equipment drive these media at a constant speed. To the extent that the speed varies, there will be a corresponding variation in musical pitch. If the speed variation is slow, we call it a "wow." If it is fast, we refer to it as a "flutter." Wow and flutter are measured as a percentage of the speed of the equipment. A piece of equipment is considered to have reasonably low wow and flutter if the speed variations are below 0.2 percent. Some feel that 0.3 percent is an acceptable amount of wow and flutter. Other experts will say that 0.1 percent wow and flutter must be attained for high quality sound. When these speed variations are extreme, we have an audible wavering of musical pitch. This is especially noticeable when listening to such instruments as the piano and the clarinet because they produce long, sustained tones. When musical tones are produced in rapid succession, the ear does not hear a particular tone long enough to perceive speed variations, except in cases of severe wow and flutter.

Wow and flutter are not necessarily present at the same time or in the same piece of equipment. Turntables will have more wow than flutter, while the reverse is true of tape machines.

Editor's Note

Most of you are supplying stamped, self-addressed envelopes with your requests for information. I very much appreciate this. I handle a tremendous number of letters, and do so without a secretary. You can readily see that the time required to make out return envelopes would be better spent in actually answering letters. Thus, it would speed up my answers to your questions.

Related to this same subject, I realize that readers who reside in countries other than the United States, do not have access to American stamps, and that it is impossible for them to supply a stamped return envelope. However, it would be of great help if the envelope could be supplied, complete with the address to which the letter is to be sent.

I gather that GI's often have a difficult time in obtaining envelopes, especially those in forward positions. I certainly can understand the problem. Don't worry about the envelopes under these circumstances.

I would also appreciate it if you all could put your return address in the body of your letters. This would help in cases where the outside and return envelopes are lost. If any of you have written and have never received an answer, it is because there was no way to forward your letter to you.

I answer every letter received, even when the questions are not suitable for inclusion in this column. However, as some of you know, when a question requires a great deal of study, it sometimes might take a while before it is answered. I regret this very much, and I thank those of you who are now awaiting such answers for your considerable patience.

-J.G.

(Audio magazine, Feb. 1971, Joseph Giovanelli)

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