If you have owned a stereo high fidelity component system for, say, five years or so, you're in for some pleasant surprises.
There's a great deal of equipment that's new and improved. As a result, it's likely that you can enhance your system's performance by changing a component or two, or even stepping up to a completely new, state of-the-art system.
Speakers. Perhaps the most likely candidate for replacement or upgrading is your pair of speaker systems. In the past half decade, the science of speaker system de sign has undergone a major transformation.
Not that there have been any truly radical new principles uncovered. Rather, some of the complex mathematics involved in purely scientific speaker system design has been reduced to "language" which can be under stood by a computer. As a result, the complex interrelationships between speaker drivers, cabinet enclosures, crossover net works and the other elements that make up a speaker design can now be dealt with more easily by speaker design engineers. The up shot: systems that more closely simulate realistic sound.
Electronics. Is it time to replace that old receiver or amplifier with a modern component? As you thumb through this directory, you will be surprised to find that, despite inflationary trends in other consumer product areas, you can actually purchase more performance per dollar in audio electronics today than you could five or ten years ago.
That's because technology has actually advanced more rapidly than the dollar's value has shrunk.
Nearly all of the audio electronics avail able today is solid state. And solid-state electronics no longer means only transistorized. More and more complex integrated circuits are being used in audio equipment. The entire stereo FM decoder circuitry, once requiring a half-dozen transistors or tubes and countless related parts, coils and capacitors, has been reduced to a single integrated circuit (IC). What's more, it performs much better than earlier decoders. delivering more stable and greater channel separation.
Moreover, it seldom if ever requires any re alignment. The same is true of the rest of the FM tuner circuitry, which now often uses solid-state permanently aligned filters in stead of adjustable coils.
There are tuners which are set to their frequency by a process called frequency synthesis. Most of them display the tuned-to frequency with digital read-outs, much like the read-outs on a quartz-controlled wrist watch-and with as great an accuracy. Do they offer audibly superior performance? Yes, because even slight mis-tuning of an FM signal causes the distortion to rise rap idly, and meters on your old model may not be accurately aligned.
If you need high power at low distortion, there are receivers on the market today which will deliver upwards of 300 watts per channel and more. There are also high-powered basic amplifiers that produce even more power. And, whereas some years ago, a rated harmonic distortion of 0.5 to 1.0% was considered to be quite good, you'll find that higher-priced receivers and amplifiers these days boast of rated distortion figures as low as 0.03% or even lower. Can you really hear the difference? Perhaps not insofar as harmonic distortion is concerned, but many of the new amplifiers and receivers can respond to signals much more quickly than did their predecessors, which renders them able to reproduce fast transients in a musical signal with greater accuracy than ever before. If you are among the "golden eared" few who can perceive these differences, you won't settle for less!
Pick Up A New Pickup. Phono cartridges, like speakers, are a class of components known as transducers. They convert one form of energy into another. In the case of a phono pickup, mechanical energy is converted into minute amounts of electrical energy. It is a fact that phonograph recordings have become better in the last few years.
Many small recording companies are now producing so-called direct-to-disc records (on which the intermediate process of tape recording, with its minute amounts of added noise and distortion, is eliminated entirely) which have higher dynamic range capability and better response than ever before. In or der to get the best from these new recordings, a new phonograph cartridge may be in order (and may be all you really need).
Modern phono pickups are better able to trace the complex signals contained in re cord grooves, and they can do so with less downward tracking force than previously possible, thereby prolonging the life of your record collection.
Of course, substituting a top-grade cartridge won't be satisfactory if you plan to mount it in a ten-year-old "record changer." Its downward tracking force of several grams would be too great for the newer, better pickups. In that case, a new turntable is in order. Perhaps you are ready for one of the new quartz-locked models that maintain speed accuracy to within a minute fraction of one percent, regardless of line voltage or line frequency variations. It, like the quartz-controlled tuner mentioned earlier, is governed by a precision, self contained oscillator whose frequency never varies at all.
Signal Processing-A New World of Sound. Perhaps your present components are rather new, but you simply aren't satisfied with the sonic balance of your system.
You've tried every combination available from your bass and treble tone controls, but you still can't get things to sound "just right." That may be a cue for you to consider the purchase of one of the new graphic equalizers on the market. These increasingly popular add-on devices (they are easily connected to any component system that has tape-out/tape-in jacks or between a pre amplifier and a power amplifier) are really nothing more than elaborate tone control systems.
Whereas simple bass and treble controls operate over a large swath of frequencies (making it impossible, for example, to boost response at around 100 Hz without also affecting response at, say, 400 Hz), graphic equalizers have multiple controls (as few as five or as many as twenty), each of which can boost or attenuate a narrow band of frequencies. This permits you to tailor the overall response of your entire system to match requirements of room acoustics or to compensate for minor aberrations in the frequency response of other components in your system. If you disagree with the tonal coloration provided in a particular recording, you can even "debate" the point with the recording engineer and alter his tonal balance to suit your own preferences.
If the objective of using a graphic equalizer is to adjust your system for "flat response" in your listening room, you may need a fair amount of test equipment (or the services of a sound contractor who has that equipment) to perform the equalization process correctly. Some makers of equalizers supply a test record which has several frequency bands of random noise recorded in it. Such test records allow you to adjust overall response of your system in an approximate manner, with accuracy of final adjustment depending upon your own hearing acuity or ability to judge equality of sound levels at different frequencies.
"Enlarging" Your Listening Room. Most of us listen to music in home listening rooms that are but a fraction of the size of concert halls. Since the listening room itself might be regarded as the final high-fidelity component in the reproducing chain, this discrepancy in room size constitutes a form of "distortion" in the reproduced sound. Re cording engineers attempt to counter this lack of realism by adding varying amounts of reverberation (delayed sound) to the re cording, but even such electronic correction fails to completely reproduce the sonic environment of a concert hall. In the case of stereo systems set up at home, both the primary and the reverberant sounds emanate from the two loudspeakers located up-front, whereas in a live concert, reverberant sounds reach the listener from the walls, ceiling and rear of the hall in a complex pat tern of reflections as sound waves bounce back and forth about the hall.
To achieve this missing effect, several manufacturers have recently developed audio time delay devices. Time delay units are usually connected to the main receiver or amplifier via one of the tape-monitor circuits. Four outputs are provided on the device. Two of these simply connect back to the tape-play circuits of the main amplifier or receiver and have no time delay introduced, while the other pair of outputs are connected to a second stereo amplifier which is used to drive an additional pair of speakers located behind the listener. These speakers are fed with a time delayed, reverberant signal whose content may be varied (by means of front panel controls on the time delay device) to approximate the acoustics of "concert halls" of varying sizes.
Devices such as these have been commonly used in professional recording applications for years, but it is only recently that complex integrated circuits have been developed which enable such time delay units to be manufactured and sold at costs within reach of home high fidelity enthusiasts.
Most makers of time delay units agree that the secondary amplifiers and the extra pair of speakers used need not be of the same high-power capacity or quality as the primary system. That is because the reverberant sound field in a live concert is normally lower in energy content than the sound field reaching your ears from on stage. Moreover, reverberant sound frequencies do not extend as high as do the primary instrumental sounds.
Increasing Music DynamicRange. When we speak of the dynamic range of music, we refer to the difference between the loudest crescendo and the softest pianissimo pas sages in a musical selection. This difference is expressed in decibels (dB). In a live performance of a full orchestra, it can easily approach 80 or even 90 dB. Yet, if you examine the specifications of tape recorders, phonograph discs or even FM radio you will find that these most important high fidelity storage and transmission media are incapable of handling this full dynamic range.
In the case of tape, for example, the maxi mum dynamic range is limited on the one hand by the residual tape hiss or noise which can "mask" very soft passages of music and, at the other extreme, by the maximum signal which can be magnetically applied to the tape. If that maximum is exceeded, high levels of distortion are heard during play back. Typically, even an open-reel tape deck cannot handle a dynamic range of much more than 60 or 65 dB; the same is true of even the best, quietest phonograph records. FM broadcast practices also limit the maximum dynamic range of material that is sent over the air (not to mention the fact that most of what's broadcast over the air is derived from phonograph discs in the first place).
Recording engineers, cognizant of these dynamic range limitations, are forced to compress the music they record to fit the medium. Whether electronically or manually, they must reduce the intensity of the loudest sounds of music and, conversely, must accentuate the levels of softest musical moments. The critical listener can easily perceive this compression (especially if he or she attends live concerts regularly) and it is this compression which detracts from the realism of the reproduced sound.
Here, again, innovative audio designers have developed a variety of devices which attempt to counter the effects of compression. One of these is known as an expander.
As its name implies, this product automatically senses the instantaneous level of pro gram signals being fed to it. making the "buds" louder and the "softs" softer. Controls permit the user to vary the amount of expansion, since not all recorded or broad cast material has been compressed to the same degree. As with all of the add-ons we have discussed thus far, the expander fits into the system easily, since it can be connected between a pair of tape-out (or tape record) terminals and a pair of tape-play (or tape monitor) terminals on most receivers or amplifiers.
Companders Make Musk Fit. If you are a serious recordist and have access to un compressed music programming (live music is the prime example), you may want to consider a dual-purpose device known as a "Compander." A compander compresses your music by a fixed ratio (usually two to one), making the loudest passages half as loud and the softest passages twice as loud.
In doing so, music which originally might have had a total dynamic range of. say. 90 dB, is compressed to a dynamic range of only 45 dB-well within the capability of even a cassette recorder and cassette tape.
During playback, the compander serves the converse function, restoring loudest passages to their full intensity and diminishing the intensity of the softest passages through a process of linear expansion. The result: music reproduced in its full, live dynamic range.
Filters and Record Scratch Eliminators. To a dedicated audiophile there is nothing quite so disturbing as surface noise from a record.
or those annoying pops and clicks which are heard when a record has been accidentally scratched through mis-handling. Even the very best high-cut filters found on receivers and amplifiers, though able to reduce the intensity of the record hiss or surface noise, do so at the expense of high-frequency response. Since surface noise consists of random high frequency noise, removing this noise with a passive filter invariably cuts out some of the high treble content of the music being reproduced.
There are available, however, devices called "dynamic filters" that can be added to any high fidelity component system.
These filters have sensing circuits which can differentiate between high-frequency noise and high-frequency musical content. When the former is present alone, the filter automatically restricts system frequency response and the hiss is gone. When musical highs appear in the program, the filter quickly "opens up" the response of the V and, even though the noise comes through again, the high-frequency music is usually loud enough to mask the noise's effect. The overall result is a reduction of high-frequency noise with no audible degradation of musical frequency response.
Perhaps even more incredible are the new "pop and click" eliminators which have recently appeared on the market. These innovative instruments can actually sense the presence of record-scratch ticks and pops.
When these appear in the signal complex, the signal flow is interrupted for a couple of thousandths of a second. The interruption is too short to be detected, but those once-per-record-revolution pops and clicks are miraculously gone! If you own a large collection of valuable records that have been accidentally scratched or damaged, you will appreciate this latest marvel of audio technology.
Perfect Fidelity. In addressing the first time buyer of a stereo component system elsewhere, we mentioned that there is really no limit to the amount of money that one can spend in the quest for perfect sound re production. The major strides towards high fidelity occurred many years ago, true. But minute. subtle improvements continue to appear each year. Amplifiers which can handle sub-sonic frequencies (even down to "zero Hz" or dc). introduced just a couple of years ago, are now finding their way even into all-in-one receivers.
The casual listener may not be able to hear the difference between them and more conventional amplifiers, but the critical listener not only hears the difference, but is willing to pay a good deal more for that difference.
Today, there is talk of entirely new approaches to sound reproduction, including such futuristic ideas as a laser phonograph disc, digital recording, loudspeakers with no mechanical moving parts, and more. The esoteric audio components of today may be commonplace in a few years. only to be re placed by still more technologically advanced audio equipment of the future. Complementing the technologically advanced, smaller group of dedicated manufacturers are a group of equally dedicated audiophiles who are willing to spend any amount of money and try the very best equipment available to further their quest for perfect audio fidelity. As a second- or third-time system buyer, perhaps you are one of them.
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Also see:
Micro-Acoustics (Phono Cartridges, ad)