by LARRY KLEIN, Technical Editor
Arp and Moog Reproduction
Q. Over the years, and most recently in the August 1973 issue, you have taken a firm stand for accurate reproduction in loudspeakers. In general, I agree with your arguments, but how does the question of "accuracy" relate to the reproduction of sound that had no original lire reality, such as the product of an Arp, Moog, or other synthesizer? Or, for that matter, the sound from the loudspeaker driven by an amplifier being fed by an electric guitar?
ARNOLD Fox
Bronx, N.Y.
A. Your question reads like a latter-day electric version of the old philosophy paradox about the sound-or lack of it-made by a tree falling in the forest when there was no one to hear it.
The "sound" of a music synthesizer is that which comes out of the speaker attached to it. Different speakers are going to produce sounds with somewhat different qualities. Therefore, it seems to me that since a recording is made from the electrical output of the synthesizer, bypassing the speaker (or headset) used by the composer to listen to the instrument, it is up to the composer of the piece to specify the speaker or headphones to be used if he wants the listener to hear exactly what he, the composer, had in mind. (This is somewhat analogous to a situation in which a composer such as John Cage states that his composition sounds the way he wants it to when in performance it is played on a piano mechanically "prepared" in a certain way.) Of course, the listener has the option of playing the subsequent record through any kind of reproducing system he wants-or even, for that matter, at the wrong speed.
The speakers that are part of electrical musical instruments are another matter altogether. The sonic characteristics of the speaker and the amplifier that drives it must be considered as much an intrinsic part of the musical instrument as is the wooden body of a Stradivarius. The difference is, of course, that any electric guitar can be hooked up to a wide variety of different amp/speaker combinations and produce a wide range of results.
Some combinations will produce sound judged preferable to that produced by some other combinations-and most rock musicians have their favorites. At the recording session, the musician usually wants to hear captured on the tape the same sonic quality he hears live from his guitar amp/speaker combination, not simply that of the guitar plugged into the mixing board. It is for that reason that in a recording session microphones are al ways used to pick up the acoustical out put of the music instrument's speaker.
Sometimes, to achieve a special effect, the guitar may be plugged directly into the mixer for one track and be picked up via amp/speaker and microphone for an other track-and the two tracks mixed in the desired ratio.
Perhaps the question can be clarified if one thinks of a music-instrument speaker as a sound producer and a hi-fi speaker as a sound reproducer.
Dolby's 10 dB
Q. I have noticed that there are several audiophile noise-reduction systems available that claim a better signal-to-noise ratio improvement than Dolby's 10 dB. Is the 10-dB improvement an inherent limitation of the Dolby circuit, or are there some other reasons for choosing that specific figure? MARTIN ROSEN
Palo Alto, Cal.
A. According to Dr. Dolby, the choice of 10 dB was made not because his B-type is inherently incapable of more, but mostly because 10 dB was felt to be the best compromise figure. As your ears will attest, the 10-dB reduction of high-frequency tape noise provided by the Dolby circuits does provide a significant audible improvement. However, if greater noise reduction treatment were attempted- say 15 or 20 dB-the "treated" tape might well be un-listenability shrill (because of excessive high-frequency boost of low-level signals) when played back through non Dolby equipment. On inexpensive cassette players the 10 dB of boost usually seems to improve the tonal balance slightly- mostly because prerecorded cassettes don't have a superabundance of highs in the first place, and cheap cassette playback equipment tends to lack the high-frequency response to repro duce fully all highs on the tape.
Product Modification
Q. I have had a lot of' trouble with my amplifier-it has been in the repair shop three or four tunes over a two year period. I recently saw some manufacturer’s service notes for my unit and it seems that practically from the day it was designed it has been undergoing changes and modifications. How is it that a well-respected company such as the one that produced my amplifier wasn't able to get the design right the first time?
ALBERT SEGAL; Detroit, Mich.
A. Although it is true that design modifications may be made to enhance reliability, it is not valid to automatically assume--as you do--that there is a necessary correlation between your amplifier's breakdown and the circuit modifications. Changes from an original design come about for numerous other reasons besides an attempt to rectify some flaw in the original design. For example. the substitution of an improved semiconductor or IC will usually require other changes in associated resistors and/or capacitors in order for it to work properly. Or a specific part may no longer he available, or the suppliers of a particular part may turn out to he unreliable in their ability to deliver or to maintain their original quality control. Or the de sign engineer may have a sudden inspiration or source for a new semiconductor that enables him to enhance the reliability or performance of a circuit.
I've said this before, but it seems to be worth repeating. Any company that puts out a product that tends to break down in the customer's home is sooner or later going to find itself in bad trouble.
The reason is not that any individual customer has any special clout, but rather that the hi-fi dealer who sold the product to the customer does. No dealer in his right mind would continue to buy the product of a manufacturer when he knows that those products are going to make the dealer's customers unhappy.
So, aside from the ethics and morality of the situation, manufacturers are by and large forced by the mechanics of the marketplace to stand behind their products, since the dealer who is between them and the customer can make or break them.
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