HIGHEST FIDELITY

Using your ears to pick the best stereo gear

You don’t need a degree in electrical engineering to understand high-fidelity sound equipment, though you might think differently if you’ve been perusing some stereo ads. It doesn’t seem right that a simple urge to get a little music into your life can let you in for the task of deciphering a lot of technical jargon. But if you want hi-fi, you’ve got to speak the language.

Hi-fi is short for high fidelity, and the phrase is used to describe equipment that can get the music off records and tapes accurately, as loudly as you like, without adding noise or distortion. To shop intelligently for high fidelity equipment, you need two things: a pair of critical, sensitive ears and a basic understanding of the specifications.

The specs measure some of the ways in which hi-fi equipment falls short of perfect fidelity. They let you know whether or not basic electronic standards are met, and they measure departures from fidelity that you might not notice while listening to a system in the dealer’s showroom. But don’t rely on the specifications alone. Some things can’t be measured at the factory: The other components in your system, the shape and size of your listening room, the kind of sound you like best.

Stick with us, and we’ll show you how to put a hi-fi system through its paces while it still belongs to the dealer. If you listen carefully now, you’ll be able to listen with more enjoyment when it belongs to you.



Turntables



Music is trapped on records in the form of little squiggles in the grooves. It’s freed by a stylus which tracks through the grooves, is vibrated by the squiggles, and produces weak electrical impulses which are fed to an amplifier, where they are made strong enough to drive a loudspeaker. The difficulty of carrying out this task with high fidelity is indicated by the price tag on the system on the facing page.

The record player has two tasks: the turntable should spin the record at a constant, accurate speed, and the cartridge should transform all the squiggles into electrical signals without adding any sound of its own. The best test of turntable performance is a solo piano recording. Fluctuations in turntable speed cause the piano’s normally bell-like tone to quaver. (Because speed fluctuations produce a “wowing” or “fluttery” sound, engineers call them wow and flutter.) Almost all single-play turntables, belt- and direct-drive, produce so little wow and flutter that even the best ear can’t detect them. But record changers, the kind you can stack several platters on, are almost all gear-driven and often prone to speed fluctuations. If you insist on stacking records despite everyone’s warning that it isn’t good for them, get a belt-driven changer, like B.I.C. or Accutrac or some Dual models. Some turntables offer a bit of speed adjustment; this will. help you get on key if you like to play along with the orchestra.

The cartridge is the place where the transformation from squiggles to electricity takes place. You’ll probably buy it separately from the turntable/tonearm combination. Unfortunately, it’s a difficult item to shop for. There are many on the market, all making the same claim: excellent frequency response- the ability to reproduce all sounds from the lowest bass to the highest violin, without giving undue emphasis to any particular range. You can compare the frequency responses of different turntable/cartridge combinations by switching back and forth between them while listening closely to the highs and lows. Some combinations will sound brighter, some darker. But a simple listening test is unlikely to tell you all you need to know about a turntable or cartridge.

As far as an engineer is concerned, the ideal frequency response would be perfectly flat, with output proportional to input at every pitch. This is not achieved by any cartridge; each emphasizes some pitches more than others. Even if a perfectly flat cartridge were available, there’s no guarantee it would be the best for your sound system. For example, if your living room is acoustically dead – with a carpet, heavy drapes, and lots of furniture – the highs will tend to get lost, so you might try an Ortofon cartridge, which delivers a little extra treble.

The question of compatibility is especially important in matching cartridge with tone arm. It’s not simply a matter of buying a cartridge that tracks the lightest and plugging it in, assuming it will be kind to your records; if the tone arm can’t handle such a light setting, the stylus will skip around in the groove, scrubbing away the squiggles.

Most manufacturers design their tone arms to work best with a particular cartridge, but they don’t tell the consumer which one. The information may filter down to audio dealers in technical bulletins, or they may learn by experimentation which combination works best. (For example, many shops recommend a Micro-Acoustics cartridge for Philips turntables, but Ortofon for Yamaha.)

Revox and Bang & Olufsen make sure their turntables will be used with the right cartridge by designing them to accept only one kind. While this approach ensures that turntable, tone arm and cartridge will match perfectly, it is difficult for many audiophiles to accept: Much of the fun of hi-fi is in buying each item of equipment on its own merits, and some people take pride in owning no more than one piece of equipment from a given manufacturer. In addition, there remains the problem of matching the turntable/ cartridge combination to the rest of the system. A turntable is an expensive item to replace, when all you may really need to change is the cartridge.

For this reason some people who are serious enough about high fidelity to lay out $15,000 for a sound system prefer to buy a turntable without a tone arm (Denon, for example) find the cartridge they like best, and then buy a tone arm to match. At least two manufacturers (SME and Formula 4) make tone arms which can be tailored to a variety of cartridges.

The tone arm isn’t the only part of the turntable that influences cartridge performance. If vibrations from the platter are transmitted through the tone arm or record surface, a deep rumbling sound will result. (Technically, this is called rumble.) Check for this rumble by listening with the treble controls turned down and the needle between songs on the record. Then cue up a cut with plenty of bass, turn the volume up and listen for a muddy sound in the bass region; this may be due to the platter picking up vibrations from the speakers.

The direct-drive turntables being advertised as a great improvement over “old-fashioned” belt-drive models are prone to problems of this kind. The belt-drive’s rapidly spinning motor is connected to the platter by a cloth or rubber belt. In a direct-drive turntable the platter is joined directly to the output shaft, without any intervening gears or belts, so the motor and the platter spin at the same rate. This is quite a feat of engineering: It’s difficult to get an electric motor to spin at a constant 33 1/3 rpm. But direct-drive’s speed control is no better than that of a comparably priced belt-drive unit. It comes up to speed more quickly than the three seconds or so a belt drive takes to get going, but this feature is of If a new sound system won’t satisfy your appetite for expensive electronics, you might consider upgrading your TV room. Several big-screen televisions have come on the market since Advent introduced the idea a few years ago. The Advent ($2395 for a five-foot diagonal model) and Mitsubishi (six-foot. $3700) units project the image onto a curved screen from a console about six feet away. Rear-projection models (Agar Superscreen, 50 inches. $2795: GE Wide-screen 1000. 45 inches, $28OO) have the projector and screen in the same piece of furniture. They don’t put out as bright an image as the front-projection models, but their proponents claim a sharper picture. For sound to match the picture quality. Rhoades makes a tuner for stereo systems that pulls in TV audio broadcasts.

Good news for prospective video-cassette-recorder buyers: VCR’s are getting cheaper every day. Following Sony’s success with the Betamax. just about every television manufacturer in the U.S. and Japan brought out a VCR last summer. Encouraged by good sales following an extensive ad campaign at Christmastime. they cut back on advertising and stalled production of new models. Sales plummeted after Christmas, the warehouses are full of last year’s models, and new models are on the way. So look for recorders listing for $1200 to he sold very close to the dealer price, around $750. Bad news for VCR owners: Taping of television broadcasts may be against the law; soon you may not be able to do it at all, legally or otherwise. Federal copyright law prohibits the unauthorized duplication of copyrighted materials for any purpose, and Universal Studios/MCA and Walt Disney productions have joined suit against Sony Corporation of America, charging that selling recorders and blank tapes promotes copyright infringement by thousands of Americans. According to manv lawyers. Sony hasn’t ta prayer under the existing law; its only hope is for Congress sanction an already widespread practice by writing new law. In case recording of TV broadcasts is pronounced legal. the networks are working on a modification of the broadcast signal that will make recording it impossible.

use only to disc jockeys and people in a big hurry.

The great drawback to direct-drive turntables is that motor vibrations can come right up through the platter to the stylus and cause audible rumble. In addition, direct-drives easily pick up low-frequency vibrations from the speakers, making the low notes sound muddy. This may not show up in the “signal to noise ratio” on the specification sheet: The tests usually used were designed to measure the performance of belt-drive turntables, which don’t have rumble problems. And direct-drive turntables have been on the market just a few years; nobody knows how long those tricky low-speed high-torque motors will last.



Tape Decks



Appearance aside, tape decks perform essentially the same job as turntables: They transport the tape at a constant speed and convert information stored in its magnetized metal-oxide film into electrical impulses. So tape decks are judged by the same criteria as turntables and cartridges – speed constancy and frequency response.

A good reel-to-reel tape machine will produce no audible fluctuations in speed, its speed constancy is comparable to a good turntable’s. But it’s much more difficult to keep flutter out of your music if you want the convenience of cassettes. While reel-to-reel decks move tape at 7 1/2 or 15 inches per second, a cassette tape runs at 1 7/8 ips (otherwise you couldn’t get 60 or 90 minutes of music into that little package). Any variation in speed will be more noticeable than if the tape were moving faster. Several larger cassette formats with higher tape speeds have been introduced (for example, Sony’s Elcaset), but they haven’t caught on, so much effort is spent in trying to reduce the cassette player’s wow and flutter. You can listen for wow and flutter on cassette decks as on turntables; on the spec sheet, anything below 0.2 percent will probably be inaudible.

Tape speed also has a direct effect on frequency response. A 20-kiloherz vibration (about the highest a human ear can hear) will occupy less than a ten-thousandth of an inch of a cassette tape; it becomes difficult to get enough magnetic energy from such a small space to reproduce the sound reliably. One way of improving frequency response from reel-to-reel and cassette decks is to use separate heads for recording and playback, instead of a combination head, as is the usual practice on home machines. In these three-head systems (the third head erases the tape) the recording and playback heads can both be designed for optimum performance; they also let you listen to a tape while it’s being recorded.



ReceiversBR>

The receiver is the place where signals from the turntable and tape deck are given sufficient oomph to make the speakers speak. It comprises three distinct sections: FM tuner, preamp (which accepts signals from the tuner, turntable, and tape deck, and amplifies and alters them a bit), and power amp (which takes the signal from the preamp, boosts it some more and sends it to the speakers). If you don’t listen to the radio you can get an integrated amplifier, a receiver without the tuner section. Or you can buy each component separately in your effort to get absolute state-of-the-art sound. Until a few years ago that was the only way to get real hi-fi. Recently, though, receivers have improved so much that their specifications equal those of all but the most expensive separates.

The main selling point of a receiver or power amp, and the principal determinant of its price, is rated power output. A receiver rated at 20 watts per channel RMS (root mean square – this refers to the statistical method by which power is measured) will play loudly enough to drive you out of the living room. So why are receivers that put out 100 watts per channel selling so briskly? Consumer psychology aside, amplifier power has an effect on fidelity even at volumes far below the maximum. As music flows through the amp at a given average power, it will demand momentary surges of several hundred times as much power. Failure of the amplifier to deliver such peak loads results in a form of distortion called clipping (because the tops and bottoms of the waveforms are cut off). To make sure you’re getting all the power you need, turn the amp up as loud as you think you’d ever want it (ask to hear it through the best speakers in the house) and listen for any muddying of the bass sounds. Clipping can burn out speakers just as surely as consistent overloading can, so take pains to get enough power to satisfy your craving for volume. Speakers vary in the efficiency with which they convert electricity to sound (from one to three percent), so even if you can’t afford all the power you’d like, you can still get an indecently loud system by choosing efficient speakers.

If you’re concerned about accurate reproduction, take along some of your favorite records of acoustic music when you go to buy a receiver (or any other stereo component). With a record of electrically amplified music, you won’t be able to tell whether the sound is being colored by your amp or the musicians’. Listen to receivers hooked up to the best turntable and speakers in the showroom – it’s the receiver’s limitations you want to explore. Compare receivers two at a time, switching back and forth Frequently; sound qualities are hard to remember, so it would be too confusing to try a three-way comparison. All the receivers you audition should be hooked to the same turntable and speakers.

After you’ve established your power requirements, you can turn to more subtle qualities. First listen to the amp turned to the “phono” setting, with no record on and the volume turned up. What you’re listening for is noise in the phono preamp. The signal from the turntable is weaker than those from the tuner and tape deck, so it must be amplified more; preamp noise will be amplified along with it, and you may lose very quiet sounds in the hiss.

Next put on a record with plenty of very low and very high sounds, like a symphony. Over a range of volumes, including very low, listen for the emphasis given to highs and lows by different receivers. This is a test of frequency response. Most receivers give nearly flat response from 20 to 20,000 herz – as far as the human ear is concerned, perfectly flat. Your dog might appreciate good fre quency response to 30,000 herz, but let him buy his own stereo. The most common deficiency in frequency response is on very low, very quiet sounds. See if your receiver can handle the end of side 2 of “Thus Spoke Zarathustra.” The quiet plucked bass notes should come through clearly.

Now listen for “clarity,” “presence,” “openness,” and “warmth,”; they’re difficult to define but easy to hear. The sound of every instrument should be distinct from all the others, but without harshness. On most recordings, voices should sound like they’re out in front of the instruments. Finally, the sounds of all the instruments should be independent of each other; the thump of the bass drum shouldn’t reverberate through the strings. A lack of any of these good qualities is due to distortion, the introduction by the amplifier of sounds that weren’t originally in the recording. Minimizing distortion is the real trick in amplifier design.

Manufacturers generally state two distortion ratings in their promotional literature: total harmonic (THD) and inter-modulation distortion (IM). Neither should be over 0.1 percent for high fidelity – but it’s important to realize that there is much distortion not accounted for in those measures.

Harmonic distortion is the addition of overtones (or harmonics) an octave or more higher than those originally in the music. It makes highs sound thin and lows sound muddy. A low THD figure doesn’t mean an amplifier is free from annoying harmonic distortion. All sounds contain harmonics; musical instruments and voices have a lot of energy in the second and fourth overtones, so a fair amount of harmonic distortion in that range is tolerable – it sounds natural. The old tube amplifiers produced quite a bit of harmonic distortion, but it lay mostly in the low harmonics. Transistor amps (virtually all the amps now on the market) generate a smaller total amount of harmonic distortion, but more distortion is concentrated in the high harmonics. Without special attention to reducing harmonic distortion, they sound very harsh.

Intermodulation distortion (IM) is a more pernicious kind of infidelity. It’s the introduction of frequencies which are the sums and differences of frequencies originally present in the signal. IM produces dissonance; at least harmonic distortion is on key. Worse yet, IM may not be obvious to the untrained ear; its principal effect is to make the listener tire quickly of music at concert-hall volumes. So it’s an important specification to check – many new receivers have less than .05 percent IM.

The list of specs is constantly growing: The newest entry is transient inter-modulation distortion (TIM or TID), and it’s just beginning to appear in hi-fi ads. Technically speaking, it’s momentary IM due to HD in the very high frequencies. Amps making a lot of TIM are often described as sounding closed and harsh, while low-TIM equipment sounds open and clear. Some methods for reducing THD increase TIM: a case of trading one spec for another.

To reduce TIM, some new top-line manufacturers (notably Lux, Crown, and Threshold) use a direct-coupled signal path. This means that the signal passes through no capacitors or inductors as it flows through the receiver. Direct-coupling is also claimed to make all the sounds tighter and clearer. Capacitors pass high frequencies faster than low ones, so eliminating them allows all the frequencies that make up a musical note to arrive at the speaker together. (What happens then is up to the speaker.)

To evaluate a receiver’s FM section, listen for low background noise and good stereo separation. Try several different stations and turn the volume down, checking for clarity in quiet passages. To test separation, switch back and forth between two receivers and play with the balance control; does one receiver confine some instruments to one channel better than the other?



Many of a tuner’s characteristics are difficult to evaluate by ear, so a close look at the specifications is in order. Sensitivity is the ability to tune in a weak signal; look for 3 microvolts or less. Signal-to-noise ratio measures the background quietness you listened for; it should be 50 decibels or more. Capture ratio is important if you live in a valley or near tall buildings; it measures the ability of the tuner to reject reflections of a radio signal in favor of the signal itself. A low capture ratio can make the sound lose crispness; look for at least 4.5 decibels. Selectivity is more important in New York, where the airwaves are crowded with FM broadcasts, than around here; it’s the ability to shut out signals very close to the one tuned in. Fifty decibels is usually plenty of selectivity.

In addition to amplifying audio signals, the receiver gives the listener the opportunity to fool with the sound a little, with controls for volume, tone, balance, and loudness. Of these, loudness is the least understood; its function is to boost the bass and treble sounds when the system is played at low volumes, to make up for some inadequacies of the human ear.

Tone controls let the listener correct some inadequacies in recordings or the listening room by giving a bit of boost or cut to the highs or lows (sometimes there’s a separate tone control for the midrange, usually labeled “presence”). Similarly, bass and treble filters let you reduce tape hiss, record surface noise, and turntable rumble, at the expense of some of the music.

If you’re never quite sure what to do with tone controls, you’ll really be baffled by an equalizer. Instead of dividing the sound spectrum into two or three ranges to be controlled separately, the equalizer provides boost and cut for each octave, to let you tailor the sound to your room and your ears. One way to use an equalizer is to have an audio technician come to your house with a microphone, oscilloscope, and tone generator, and get the frequency response as flat as possible in the vicinity of your favorite chair. But there’s no guarantee you’ll like flat response once you’ve heard it; no concert hall has flat response, yet the sounds heard there are often quite pleasant.



Speakers



Audiophiles have fairly strong opinions about the relative merits of various turntables, tape decks, amps, and tuners: but the best way to start a fight between any two hi-fi nuts is to ask what the best speakers are. Speakers color the sound of a hi-fi system more than any other component; choosing the coloration you like best is a matter of taste, about which there is always argument.

Designing speakers is more of an art than designing other components because the objectives are less clear. Every other component can be hooked up to a test machine, and its output can be displayed on an oscilloscope. The engineers know what’s required: flat frequency response, no noise, no distortion. A speaker’s sound can be picked up by a microphone and fed to an oscilloscope, but what’s measured isn’t just the sound of the speaker- it’s the sound of the speaker plus the room it’s sitting in. They don’t know anything about your living room at the speaker factory.

Though you won’t know how a speaker will sound until you get it home, there are tests you can perform in the showroom to increase your chances for satisfaction. The first step is to match the speaker’s power requirements to the output of the amplifier. Speakers are rated for minimum and maximum amplifier power. Getting the volume you want from the amplifier power you have is a matter of speaker efficiency.

Loudspeakers are extremely inefficient at converting electricity into sound. Only 1 to 3 percent of the power from the amplifier ends up as sound: the rest heats the room. The most common speakers are of the acoustic suspension type, in which the drivers (the cones that move the air) are mounted in a sealed cabinet. This is a relatively inefficient design – but that’s not necessarily a drawback. Acoustic suspension speakers give better performance for their size than any other design, so they’re the way to go where space is a consideration. Just be sure your amp can drive them as loudly as you like. The newest refinement of the acoustic suspension design for rooms that just won’t hold big speakers is the six-inch cube bookshelf speaker, which delivers remarkable frequency response down to 70 herz. Lower sounds can be handled by a separate sub-woofer; it can be placed anywhere without spoiling the stereo effect, because you can’t hear where very low sounds are coming from. In bass reflex speakers, a hole is cut in the cabinet to let some of the bass sound out. To give the same performance as acoustic suspension speakers, bass reflex designs generally have to be a bit larger. They’re roughly twice as efficient as acoustic suspension models. Most bookshelf-size acoustic suspension speakers require about 20 watts per channel; bass reflex speakers can get by with 10 watts.

Having selected a group of speakers that fit your criteria for price, size, and volume delivered, compare them for frequency response by listening to records with plenty of highs and lows. (Symphonies and piano music make the best tests.) Listen for clarity and definition of individual instruments, as you did when testing receivers. Be sure to listen at low volume as well as high. Watch out for first impressions; a speaker which at first seems to have solid bass and brilliant highs may strike you as boomy and over-bright once you’ve lived with it for a while. You want to listen to the music, not the speakers.

To improve frequency response, most speakers divide the sound spectrum up among two or more drivers, so that each driver can be specially made to handle a narrower range of frequencies. A two-way speaker contains a “woofer,” a “tweeter,” and an electronic crossover to send the low frequencies to the woofer and the highs to the tweeter. A three-way speaker adds a mid-range driver (or “squawker”) and another crossover. The crossover is the weak link in many speakers. The best test of the crossover network is a recording of an unaccompanied female vocalist; a woman’s voice will move from woofer to mid-range to tweeter as she sings a scale. If the tonal quality of her voice changes as it goes from low to high, the speaker has crossover problems. There is usually a control on the crossover to let you boost or cut the sound going to the tweeter, to let you tailor the speaker to your listening room. You can also use this control in testing a speaker to listen to each driver separately.

Deficiencies in crossover performance have prompted some engineers to move the crossover to the preamplification stage, where it’s technically much easier to get good crossover performance. This kind of design requires two power amplifiers for each crossover and a lot more money.

Pay careful attention to the way a speaker handles low notes. Harmonic distortion in a speaker generally shows up as “doubling” in the lower registers: Deep bass sounds are paralleled one octave higher. If the bass drum sounds a bit like a tuba, you’re probably hearing doubling. The bass register is also the place to listen for transient response. This is the ability to handle rapid changes in power level: the “attack” as a guitar is plucked or a piano key is struck, or the sudden start-and-stop of a drumbeat. Poor transient response can often be heard as a bit of reverberation in low drum sounds.

A property related to transient response is phase coherence, the degree to which sounds coming off the record together reach the drivers at the same time. Some speakers employ special circuitry in the crossovers to ensure that a note divided between two drivers reaches them at the same instant. This technique is called phase linking. Engineers disagree about the need for phase linking: Tests show that people can’t detect even a two-millisecond delay between two sounds. This is far more delay than that introduced by a crossover that isn’t phase linked. But proponents of the design argue that their sound is especially crisp. Ask the man who owns one.

Don’t just stand in front of the speakers you’re testing – walk around a bit. Since you probably want to hear all the music from anywhere in the room, look for a speaker that puts sound out to the sides as well as straight out in front. Such a speaker is said to have good dispersion. High frequencies are especially difficult to disperse. The best test is to tune in some between-channel noise on FM and walk around the speaker, listening for any muting of the hiss as you move around to the side. Most current speaker designs use dome-shaped tweeters instead of cones to achieve good high-frequency dispersion.

Finally, listen to the speakers at a comfortable volume, perhaps with your eyes closed. Does each instrument seem to have a definite location in space? Do voices seem to be out in front of the band? If so, the speakers have two good but hard-to-define qualities, stereo image and presence. Now stop thinking about tests and comparisons and just listen. Do you like the sound? If so, these may be the speakers for you.

But you won’t know for sure until you’ve hooked them up at home. The sound you get in your living room is the sum of all the colorations added by each component and the room itself, and there’s no way to know how it will all sound until you turn it on.

How to Talk Hi-Fi



A/B test: Comparing two components by switching back and forth between them – the best way to evaluate stereo gear.



Compliance: The ability of a stylus to respond to squiggles in the record’s grooves. Expressed in centimeters per dyne: the higher the better, but be sure cartridge and tone arm are a good match.



Decibel: A measure of relative sound intensity, abbreviated dB. A 3.2 increase corresponds to a doubling of energy; it’s the smallest change detectable by the human ear.



Dynamic range: The range (in decibels) from the loudest to the quietest sounds in a group of sounds.



Frequency: The number of vibrations per second in a sound or electrical signal. High frequencies produce high tones, low frequencies produce low tones. Expressed in herz (Hz) or kiloherz (1 kHz = 1000 Hz).



Frequency response: The ability to reproduce a range of frequencies evenly.

Harmonic distortion: Tones added by the stereo system which are one or more octaves higher than tones originally in the recording. Given as a percentage – 0.1 percent or less is considered hi-fi.



Selectivity: The ability of a tuner to receive only the desired station while rejecting other stations. Measured in dB – the higher the better.

Sensitivity: The ability of a tuner to pull in weak stations. Measured in microvolts – the lower the better.



Separation: Degree to which left and right channels remain distinct in cartridge, amp, and tuner. Measured in dB – the higher the better.



Transient: Abrupt change of state – quick change in signal amplitude, caused by percussion instruments, “attack” of plucked strings, etc.



Transient response: The ability of amplifier and speakers to reproduce transients without letting them overstay their welcome.

If Your Records Still Don’t Sound Good



After spending $15,000 on a hi-fi system, you may find yourself unhappy with your record collection. Your amp and speakers will play records faithfully right up to the threshold of pain, but the cres-cendi of a recorded symphony still don’t have the sweep you hear in a live performance. The system adds virtually no noise to what it plays, yet pianissimo passages are swamped in pops and hisses. The fault lies not in the sound system but in what it’s fed.

One of the things that make live music lifelike is its dynamic range, the difference in volume between the quietest and-loud-est sounds. A live symphonic performance has a dynamic range of 100 decibels; most records offer only 25 to 40. Some loss of range (compression) is due to the many stages of tape mixing involved in the production of most recordings: You can get about 80 decibels of range on tape, so a little compression occurs with every mixing step. Some of the compression is intentional: Most record players would be unable to cope with a 100-decibel range. Soft passages would be inaudible, loud ones badly distorted. Finally, the quiet passages are recorded much louder than they have to be so that surface noise on the record won’t be too blatant; this is much cheaper than improving quality control in record production.

You can reduce surface noise considerably just by shopping for records more carefully. With a few exceptions, American record companies make noisy records, and European companies make quiet ones. Some European labels are hard to find, but worth the effort: There’s some fine jazz on the ECM label, and much of the Angel classical catalogue originates on European labels owned by EMI, Angel’s parent company. You can also get a few records with 60 decibels or so of dynamic range: Many hi-fi shops sell direct-to-disc recordings, copies of a master disc cut during a performance, without any taping steps or consequent compression.

Because of the limitations of commercial discs, many audiophiles expand the dynamic range of recordings electronically. There are several devices on the market which reverse the compression process, making louds louder and quiets quieter. The problem with most of them is that you can hear them working: They “pump and breathe” in quiet passages, making sudden and unwanted changes in volume and hiss level. The 3Bx Linear Expander by dbx is much less obtrusive than most. It divides the sound spectrum into three bands and treats them separately, greatly reducing unwanted cres-cendi and diminuendi. An added benefit of expansion is that record surface noise is much reduced.

The background noise inherent in magnetic tape can be quieted in making recordings by compressing the sound as it goes onto the tape, then re-expanding it on playback. That’s the principle behind the familiar Dolby B noise reduction system found on most cassette decks. High frequencies are compressed as the sound is being recorded, then re-expanded on playback. On re-expansion, the tape hiss (which was added after compression) is reduced by about 10 decibels – a significant improvement.

Dbx sells a system which reduces tape noise even more. While Dolby (and JVC’s similar ANRS system) just compress the high frequencies – that’s where most of the noise is – dbx compresses the whole sound spectrum two-fold in recording, then reverses the process on playback. Tape noise is reduced by 25 to 30 decibels, and more dynamic range can be included in the tape.

Dbx noise reduction does an excellent job, but it has some disadvantages. While a Dolby-recorded tape will sound just a little bit bright when played without Dolby, dbx-recorded material sounds terrible when played back without dbx. And with dbx it is essential that the tape and tape deck be top-quality. Any variations in frequency response from the tape or the deck in playback will be doubled by the dbx unit, adding unwanted dynamics to arpeggios and glisses: It’s a good idea to have the tape deck’s frequency response calibrated by an audio shop.

With expansion and noise reduction, you can make taped copies of records with more dynamics and less noise than the originals. But the problem with all expansion and noise reduction units is that they put the sound through another amplifying stage, adding distortion along the way. What is needed is a whole new way of recording sound.

In 10 or 15 years, records and tapes as we know them may be obsolete, replaced by pulse-code-modulated (PCM) recordings. Records and tapes are inherently noisy because they contain too much information: Record scratches and tape hiss can’t be distinguished from recorded sounds in the playback process. On a PCM recording, the sound waves are sampled every few microseconds, and the frequencies and amplitudes are stored digitally. There’s no noise because the playback system is in effect reading numerical values, which are unaffected by small imperfections in the recording medium. Because the volume is dependent on the magnitude of a number instead of the motion of a needle, dynamic range is limited only by the amp and speakers.

PCM equipment will be on the market next month, but it will be expensive. Sony expects to sell (for $4,000) a device which converts its $1,100 video tape recorder into a PCM sound recorder. If you can wait a bit longer, Mitsubishi has an even trickier way of storing sound – as a pattern of spots on tape or disk, to be scanned by a laser. The information then goes into a memory, and a quartz clock controls the speed at which the information is retrieved. This way, speed fluctuations in the turntable or tape transport will have no effect on the sound.

A sound system is greater than the sumof its parts. Hook up the components andyou have more than a collection of expensive electronics – you have music.The key to getting music you’ll be happywith is to buy components that work welltogether. Remember that all the elementsof the system and the room they’re playedin color the sound. The best strategy forstereo shopping is to ask plenty of questions about how well the componentsyou’re considering will match. And youshould be able to return a component ifyou find that it doesn’t fit in – after all,you’re spending a lot of money.

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