For the Record

Hi-fi shopping is still one of the most confusing things a consumer can do. What’s the novice – or even the moderately expert shopper – to do when faced with the vast selection of components, each of which promises to do the same thing only better than the others? Add to that the esoteric jargon of the sound buff, and you may give up and settle for something you don’t really want just to get out of the store. So in this year’s guide to stereo and home entertainment equipment, we’ll try to make things as simple as possible.

First of all, there’s no way around it: You’re going to have to deal with stereo salesmen. Keeping that in mind, here are some rules to follow:

Don’t be intimidated. If you come across a salesman who describes everything in a rapid-fire burst of technical terms, either turn on your heel and find another store, or firmly but politely ask him to slow down and explain things more clearly. If he can’t tell you about the equipment precisely and in language you can comprehend, he’s a lousy salesman and probably doesn’t know what he’s talking about.

Beware the salesman who talks constantly of “bargains” and “good deals” rather than good sound. Naturally, you want the most for your money; but if he’s hustling for a quick sale, you probably don’t really want what he’s pushing.

Ask a lot of dumb questions. Chances are, they’re not that dumb. To help you find a system that’s right for you, a salesman needs to know a lot of little things – how large a room the equipment will occupy; what kind of furniture, carpets, curtains it has; what kind of music you listen to, and how loud you play it.

Spend more time listening than talking. Any good hi-fi store will provide a means of conducting comparison tests. Take along a favorite record (preferably acoustic music – it’s pretty hard to tell whether electronic music is being reproduced faithfully); that way you can listen to the same music in different stores. In the comparison tests, all or most of the components will be hooked up to a central switchboard that allows you to change quickly from one component to another. The speakers will be connected to the same amplifier or receiver; or, if you’re comparing receivers, they’ll be connected to the same pair of speakers. Make sure not to change the volume between comparisons – a louder speaker or receiver will appear to be a better component. When you’ve narrowed it down to semifinalists, ask the salesmen to hook them up without going through the switchboard. Sometimes this is too inconvenient, but it will help you hear the components without added color or noise.

Use spec sheets cautiously. Specifications should ideally give some indication of the ways in which audio components fall short of perfect fidelity. But beware: A spec sheet from one manufacturer rarely resembles that from another. Even highly trained technicians are confused by them – there are endless ways in which specifications can be presented.

If you still feel compelled to examine specs, here are a few pointers on how to read them: The amount of power an amplifier delivers should be quoted as a root mean square value (RMS). The RMS is a conservative figure, indicating the power output your amplifier can deliver continuously over a given period. If the figure quoted represents both channels being driven at the same time, divide it in two to determine how much can be sent to each individual channel. The quoted value is usually for 8 ohm speakers – the most common speaker impedance – so if you have 4 ohm speakers the rated power will double, and if you’re pushing your amplifier through a 16 ohm load, the power will be cut in half.

As for distortion specs, almost any respectable component will produce 0.1 percent or less total harmonic distortion (THD, the type of distortion most commonly listed), which is well below the audible range. In some cases, attempts to lower THD increase other types of distortion, so it’s not always wise to shop for the lowest possible percentage. The amount of distortion will vary according to the frequency being reproduced and the amount of power being delivered, so distortion specs should include qualifications concerning frequency range and power output. A good spec on an amplifier should read something like this: “60 watts minimum continuous power channel into 8 ohms loads, both channels driven, 20 Hz-20,000 Hz with no more than 0.02% total harmonic distortion.”

Frequency response is given in Herz, or cycles per second. It should be flat over a wide range, which means that over the entire spectrum of frequencies a given component can reproduce, no individual frequencies will be emphasized or de-emphasized. A flat response curve will be roughly a horizontal line, without any significant peaks or valleys. Make sure a frequency response spec includes an indication of how far above or below flat response each frequency will be. Anything less than ±3 decibels can be considered a flat curve; many components will be within ±2 dB.

A signal to noise ratio (S/N) is given for most components; it tells you how much louder the desired sound will be than the inevitable but unwanted background noise. An S/N ratio of 45 decibels is acceptable. The higher the number the better.

No matter how impressive the specs, however, your best judge of the quality of a system is still your own ears. Trust them, not the numbers.

With those rules in mind, you can begin shopping with confidence. Now for a few pointers on the individual components that make up your system.

Speakers

Shop for your speakers first. No other component will have so noticeable an effect on the sound of your system.

Endless attempts have been made to create the “perfect” loudspeaker, and the result is a huge number of speaker designs in every shape and size imaginable. There are a few basic designs, however, and these are all the average consumer needs to know about.

Speaker cabinets come in two basic designs. One is the acoustic suspension cabinet, which has speakers mounted in a sealed box. This design offers the advantage of high fidelity in a small package, but requires a lot of power to produce a reasonable amount of sound. The other common design is the reflex cabinet. It has holes cut in the front baffle which allow the sound waves produced by the back of the speaker cone to escape from the box and combine in phase with the sound produced by the front of the speaker. Bass reflex speakers generally offer fuller bass response and are, on the whole, more efficient than acoustic suspension designs, but they usually require larger cabinets.

Most speakers are either two-way or three-way systems. The two-way design has two speakers – a “tweeter” to handle mid and high frequencies and a “woofer” for the lower frequencies – in each cabinet. A cross-over network separates the frequencies and sends them to the appropriate speakers. A bad crossover network will noticeably alter the tone quality as the music moves up the scale. A number of speakers feature phase coherent networks, designed to make sure the cross-over network sends the different frequencies to each speaker at exactly the same time. The speakers are also aligned vertically in the cabinet, so the sound from each will reach the listener simultaneously. The advantages and disadvantages of this design are still being debated, but most people agree it doesn’t adversely affect the sound.

The three-way design has three speakers in each cabinet and two crossover networks. A mid-range speaker joins the tweeter and woofer. While many people insist this mid-range speaker offers better and more sensitive control over the sound, others argue that the more crossover networks you have, the more trouble you’re likely to have. In the end, your ear will have to judge the relative advantage of three-way or two-way systems.

A more recent fad is the “mini-speaker.” A number of manufacturers offer very small speakers which produce startlingly good sound and still fit on the most crowded bookshelf. Some mini-speakers are designed to be used as “satellite” speakers to a sub-woofer that handles the very lowest frequencies (generally below 100 Hz). Your ears can’t tell where very low tones are coming from, so you don’t need stereo for deep bass. The two mini-satellites can be placed in the room for maximum dispersion of the middle and high frequencies – the ones where stereo effect is clearest. A sub-woofer should have its own power supply. If one isn’t built into your current system, you’ll need to buy an additional amplifier.

Technology aside, choosing speakers depends mainly on what kind of music you listen to and where you listen to it. If you listen to rock ’n’ roll or disco, you want speakers with full, even exaggerated, bass response. Each bass note should be heard distinctly, without “boominess” muffling the rest of the music. Listen to several pairs of speakers at low volumes. The pair that delivers the most bass at low volume will serve you best.

For classical music you want the most accurate speakers you can find. They should be able to produce a wide dynamic range, from the softest solo violin to the loudest orchestral tutti, with equal integrity. One of the best tests for accuracy is a good recording of a solo piano. If you can close your eyes and be convinced that a Steinway concert grand is being played in front of you, you’ve found a high quality speaker. Recordings of both male and female vocalists are also good for testing speakers. If the voices sound nasal or in any way unnatural, look for another speaker.

The high frequencies are the ones most affected by the room in which you listen to music. If you have carpeted floors, heavy draperies, and lots of cushions in your listening room, you need a speaker with a strong high frequency response so you can put an edge on all those soft surfaces. High frequencies are tiny and delicate. They don’t spread out easily in the room. Good speakers disperse the higher frequencies at a wide angle. One way of testing your speakers’ dispersion capability is to set your FM tuner between stations. The hiss you’ll hear is white noise, which contains all frequencies in the spectrum. Now walk around the speakers and move from side to side. If you hear no appreciable difference in the sound quality of the white noise when you’re standing beside the speakers instead of in front of them, they have good dispersion characteristics.

Many manufacturers prefer dome or convex tweeters instead of cone-shaped or concave tweeters because they offer better dispersion. Most top-quality speakers also have a high frequency adjustment switch that allows you to increase or decrease the output of the tweeter. If your living room has hardwood floors, no curtains, and lots of chrome and glass furniture, you may want to reduce the brilliance of your speakers’ upper register.

The last characteristic to check out is “imaging.” On a well-engineered recording, the musicians are placed in their appropriate sound fields. The violins should be heard to your left and the cellos to your right, the woodwinds at center and a little back, and the solo vocalist or instrument in the front of the rest of the ensemble. If the recording sounds like an impromptu concert by a restless mob in Texas Stadium, find some other speakers.

Receivers

Most receivers are made up of three parts: FM tuner, preamp, and power amp. If you don’t listen to the radio, you can buy an integrated amplifier without the FM tuner. Or, you can buy each of the three components separately, which used to be the only way to get real hi-fi. Today, only the most expensive separate components are better than the receivers that contain all three.

The preamp takes the signal from the tuner, the turntable, or the tape deck and alters it a bit; the power amp then takes the signal from the preamp, boosts it some more, and sends it to the speakers. The main selling point of a receiver is rated power output. Even if you don’t want to play your records so loudly you can hear them across the street, you need a receiver with a lot of power. The RMS rating, remember, is a conservative figure. As music flows through the amp at a given average power, it demands momentary surges of several hundred times as much power. Failure to deliver 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, have the store hook the amp you’re considering to the best speakers in the house; then turn it up as loud as you think you’d ever want to hear it and listen for any muddying in the bass. Compare receivers two at a time, switching back and forth. All the receivers you audition should be hooked to the same turntable and speakers-the best in the store.

Once you’ve found a receiver with the power you need, turn the amp to the “phono” setting, with no record on the turntable, and listen with the volume turned up. The signal from the turntable is weaker than those from the tuner or the tape deck, so it must be amplified more. Preamp noise will be amplified along with it, so this test gives you a chance to hear the hiss in which very quiet sounds from your records may get lost.

Then 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. 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 Spake Zarathustra.” The quiet plucked bass notes should come through clearly.

Once again, listen for the clarity and precision of the recording. A lack of presence, openness, and warmth may be the result of the amplifier’s introducing sounds that weren’t originally in the recording. Only a few kinds of distortion appear on the spec sheets, and some circuit designs minimize one type of distortion by increasing other types.

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. Comparing two receivers, play with the balance control: Does one receiver confine some instruments to one channel better than the other?

Spec sheets, if you know how to read them, can help you evaluate a tuner’s capabilities that can’t be evaluated by ear. Sensitivity is the ability to tune in a weak signal; look for 3 microvolts or less. The signal-noise ratio should be 50 decibels or more. Capture ratio measures the ability of the tuner to pick out a radio signal from reflections of that signal off tall buildings or other obstacles; look for at least 4.5 decibels. Selectivity is the ability to shut out signals very close to the one tuned in. It’s more important in New York, where the airwaves are crowded with FM broadcasts, than in Dallas. Fifty decibels is usually plenty of selectivity.

Some manufacturers are offering digital frequency synthesized tuners that lock into stations and don’t let go, giving in some cases better capture ratios and selectivity. Don’t confuse them with the conventional tuners that give a digital read-out for cosmetic purposes only. But don’t bother spending too much on a tuner: The radio broadcasts they receive are never top-quality sound, and even the most expensive equipment can’t turn mid-fi into hi-fi.



Turntables

The record player has two tasks: The turntable should spin the record at a constant, accurate speed, and the cartridge should transmit its electrical impulses without adding any sound of its own. The best test of a turntable’s performance is a solo piano recording. If the turntable’s speed fluctuates, the piano’s normal belllike tone quavers, and produces a “wowing” or “fluttery” sound that engineers call, for obvious reasons, wow or flutter. Almost all single play turntables, belt- and direct-driven, produce so little wow and flutter that the best ear can’t detect them. But record changers 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 the option of speed adjustment, a refinement you may want if you like to play along with the orchestra, since you can tune the record to your instrument by a slight adjustment of the record’s speed. Opera buffs who collect long-playing recordings to which early 78’s have been transferred also find speed adjustment valuable, since some “78’s” were actually recorded at slightly slower or slightly faster speeds, completely altering the singer’s vocal qualities and the key in which the music was sung. Few record companies take the trouble to adjust these old recordings to the proper speeds when they transfer them to 33 1/3 recordings.

You’ll probably buy the cartridge separately from the turntable/tone arm combination. Unfortunately, a listening test isn’t likely to tell you all you need to know about a cartridge or a turntable. No cartridge achieves a perfectly flat frequency response; each emphasizes some pitches more than others. And even if it did achieve that ideal flatness of response, it might not be ideal for your listening place. If you have an acoustically dead living room, with lots of carpets and upholstery, you might want a cartridge like the Ortofon, which delivers a little extra treble.

You also have to deal with the problem of compatibility of cartridge and tone arm. It’s not simply a matter of buying the 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.

Low-mass tone arms are a popular new item. They’re designed to go with high-compliance needles, which cause a lot of problems if they’re used with heavy tone arms. If a high-compliance needle is supporting too much tone arm weight, any movement will cause an even greater movement in the tone arm, making it hop out of the groove, and sometimes break the needle. Any slight dip or bump in the record will cause a heavy tone arm with a high-compliance needle to skip and jump. Bang & Olufsen markets the most popular low-mass tone arm/high-compliance needle combination.

Most manufacturers design their tone arms to work best with a particular cartridge, but they don’t tell the consumer which one. Your audio dealer may have found out either by experience or from reading technical bulletins. Many shops, for example, recommend a Micro-Acoustics cartridge for Philips turntables or Ortofon for Yamaha.

The tone arm isn’t the only part of the turntable system that influences cartridge performance. Vibrations from the platter, transmitted through the tone arm or the record surface, cause a deep rumbling sound. Check for this rumble by listening with the treble controls turned down and the needle between cuts on the record. Then put the needle on a cut with plenty of bass, turn the volume up, and listen for a muddy sound in the bass.

Feedback is particularly a problem on the new direct drive turntables which are often advertised as a great improvement over “old-fashioned” belt-driven ones. In fact, only the highest quality direct-drives-the Revox tangential tracking turntable for example-compete with belt-driven ones. In the belt-drive machine, a cloth or rubber belt connects the platter to the motor. In a direct-drive machine, the platter is joined directly to the output shaft of the motor. Direct-drive machines come up to speed more quickly than belt-driven ones, but this feature is useful only if you’re a disk jockey.

The drawback of direct-drive turntables is that motor vibrations come directly to the platter, and easily cause rumble. They also pick up low-frequency vibrations from the speakers, causing feedback. These deficiencies usually don’t show up on spec sheets. And direct-drive turntables haven’t been on the market long enough to test how long their very highly stressed motors will last.

Accessories

Once you’ve mastered the basics, you’ll probably be hooked. That’s the point at which you’ll want to investigate some of the following refinements, which make your living room an ever-closer approximation of a concert hall.

An equalizer lets you tailor the sound for your room’s acoustic characteristics. It adds or subtracts power for each octave, which can be a pretty tricky process to handle on your own. The best way to use an equalizer is to have an audio technician visit your house with a microphone, oscilloscope, and tone generator, and get the sound just right in the vicinity of your favorite chair. Then set the controls and don’t change them – until you decide to move the chair, at which point you need to have him start all over again. Macintosh sells an equalizer that has no external controls; a technician wires in the appropriate circuits, then seals it up. This not only eliminates the temptation to twiddle, it gets rid of the noise inherent in control knobs.

Remember quadraphonic sound? Ever since four-channel recordings were a marketing flop, audiophiles have been fiddling about with other ways to approximate concert hall realism. The latest is digital time delay, in which two small speakers in the back of the room are adjusted to receive the same signal as the main speakers, but a few milliseconds later – creating the illusion of a sound-reflecting wall at the back of the concert hall. The length of the delay can be adjusted, varying the “size of the hall.” Realism isn’t cheap: The ADS Model 10 Digital Time Delay – delay unit, amplifier, and speakers – sells for $1000.

Because of the limitations of commercial recordings, whose dynamic range is only 25 to 40 decibels (a live symphonic performance has a range of 100 decibels), many audiophiles expand the dynamic range electronically. The problem with many of these devices is that you can hear them working – they “pump and breathe” in quiet passages, making sudden changes in the volume level. The 3Bx Linear Expander by dbx is less obtrusive than most. It divides the sound spectrum into three bands and treats them separately, reducing unwanted volume changes.