by Larry Klein
Rock Tracking Force
Q. I'm a hard-rock fan, and I was wondering if there should be a different tracking force for rock discs than for "nor mal" or easy-listening discs. I've noticed some distortion in the louder parts of my hard-rock discs, while quieter music seems to come through distortion-free.
-ROBERT BAKER; Rahway, N.J.
A. The tracking force required in a given record player is that which is necessary for the stylus to track the record groove accurately. This is determined, in turn, by the forces in the playing process that tend to drive the stylus out of the groove. To put it another way, the applied vertical tracking force must at all times be greater than the various forces that operate to cause the stylus to lose contact with (mistrack) the groove walls. It's the mistracking that produces the distortion you hear.
The forces contributing to mistracking can be divided into those that affect tracking at low frequencies and those that affect it at high frequencies. The low-frequency problems are usually the unsubtle ones; the stylus "sticks" or jumps grooves, or it reproduces a variety of low-frequency thumps, bobbles, and quavers. These problems are almost always caused by record warps, too low a tracking force, improperly set anti-skating force, a bad mismatch between tone-arm mass and stylus compliance, or a combination of these factors.
The high-frequency tracking problems appear as overly sibilant "sss" sounds and a sort of "break-up" or raspy quality on loud high-frequency passages. High frequencies are embodied on a disc in the form of very rapid undulations in the record-groove walls. If the moving part of the phono stylus has too much mass-and hence too much inertia-to follow these rapid twists and turns, it will momentarily lose contact or bounce from peak to peak when things get really rough, and this results in exaggerated sibilants and raspiness. Applying more vertical tracking force may produce more reliable contact during such stress conditions.
But keep in mind that any vertical-force increase must be kept within the range of the cartridge's rated tracking force. If the manufacturer rates the cartridge for 1 to 2 grams of tracking force and the distortion is still heard at 2 grams, it may mean that your ear is better than your cartridge (and one or the other should be replaced), your tone arm needs help, or the record has been so overcut that no cartridge will play it cleanly. In any case, may the tracking force be with you.
MM and MC Cartridges
Q. I don't understand one aspect of the switch labeling on some of the new equipment. On some of the expensive components the phono-input characteristics can be switched to accommodate moving-coil (MC) or moving-magnet (MM) cartridges.
But aren't there other types of cartridges on the market besides those two?
A. TOBIN; Denmark, S.C.
A. There certainly are, but the term MM is used pseudo-generically to indicate a phono cartridge, usually magnetic, whose load-impedance requirements and signal-output voltage fall within certain values.
These vary in respect to signal output (say, 0.5 to 5 millivolts) and are generally fixed in regard to the required input impedance (47,000 ohms). Moving-coil cartridges have output voltages ranging from a tenth to a hundredth that of the MM type of cartridge, and additional boost must therefore be supplied by a step-up transformer or pre-preamplifier "head amp." Cartridges other than MM or MC types, if they are to work into inputs designed for MM or MC cartridges, usually need internal circuits to ad just their outputs for the appropriate electrical characteristics.
Unnatural Digital Discs?
Several months ago, I bought some digitally mastered discs because of the favorable comments your magazine has made about such digital processing. These records sound unnatural-which is be cause they are made by an unnatural process. And since they sound unnatural they cannot be classified as true high-fidelity records. Any comment?
-JOSEPH SA BOL; Conneut Lake, Pa.
A. Unnatural? There's nothing "natural" about any aspect of the recording and reproduction process, whether done by old-fashioned analog or new-fangled digital. What is "natural" about microphone diaphragms converting sound waves into minute electrical signals which are then amplified, equalized, compressed, converted to magnetic patterns on a master tape, stored, reconverted to electrical signals, expanded, equalized, amplified, and used to drive a device that cuts grooves into a lacquer master disc that becomes the prototype for the disc you play at home? What I've described, once over lightly, is the "natural" way a conventional analog disc is produced. A digitally mastered disc is no more or less natural, differing mainly in the form in which the signal is stored on the master tape and in the elimination of some of the compression/expansion and equalization processes.
All of the above is not meant to imply that Mr. Sabol did not hear something disturbing in his newly acquired digitally mastered discs. However, to assume that the bad sound heard is a result of the digital mastering employed is just poor logic.
As a little exercise that may be helpful in other areas of hi-fi evaluation, consider these possibilities:
(1) Product A sounds good, and its de signer states that it uses a new technology.
(2) Product B sounds bad, and its designer states that it uses a new technology.
When I'm faced with either of these two circumstances, I resist as best I can the normal human tendency to leap to a conclusion. I have usually found it best to withhold opinions on the possible causal relationship between the sound of a new product and its technology until time and/or a deeper investigation have revealed the facts.
I say "usually," because when a reader wrote recently claiming that he had found that some types of speaker wire sound better with one end attached to his amplifier than the other, I did come to a fast conclusion-and not about the wire either.
External TV Speaker
Q. Would it be possible to upgrade my TV sound by substituting a good external speaker for the one in the TV?
JOSEPH MITCHELL; La Jolla, Calif.
A. Sometimes yes, sometimes no. It depends on whether the major faults you hear arise from inadequacies in the speaker itself or from the TV audio section feeding it. In the past I have found that using an external speaker with a set often simply revealed buzz, hum, and hiss that the internal speaker didn't reproduce. On other occasions, with other sets, the improvement was worthwhile. In any case, unless you have some experience with electronics (or have a usable earphone-output jack), leave the external-speaker wiring connections to a competent technician.
Also see:
The Shorter Guide to Cartridge Shopping
Source: Stereo Review (USA magazine)