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This Month's Shopper-1 - Off Duty/Europe/December 76.
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By LARRY MYERS

YOU DON'T REALLY have to include a turntable in your hi-fi system. You can just listen to radio broadcasts or play tapes. But for most of us a hifi system without a turntable is like breakfast without coffee - it just doesn't seem complete.

In the following paragraphs we're going to take a look at the equipment you need to play records, from turntables and phono pickup cartridges, intended for inclusion in component-type audio rigs, to all-in-one compact systems that consist of a turntable and all the other equipment you need to listen to records.

If you buy a compact system you don't have to worry about choosing a turntable. The manufacturer has done it for you, selecting a unit that is compatible with the rest of the system.

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However, you may find it helpful to know just what you're getting, so study the next several paragraphs before you make a decision. Of course, this information applies to separate turntables, too.
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In hi-fi's early days there were two basic types of turntables - record changers and manuals. The early changers played a stack of records automatically but their heavy tone arms and cumbersome mechanisms didn't appeal to the audiophile. They turned instead to manual turntable designs, with separate tone arm, that offered better performance and were also easier on records than the changers of the era.

As demand for more sophisticated audio products grew, changer makers began refining their equipment and soon the term "record changer" no longer seemed appropriate for a unit with performance equal to or better than that of earlier manuals. So, the name "automatic turntable" was adopted. Although today there's still some semantic confusion, you'll find that four basic types of turntables have evolved from previous manuals and automatics.

These units play a stack of records in sequence without any intervention by you. They also play just one record automatically if you wish, lowering the tone arm onto the record, lifting it off at the end, returning the arm to the rest and shutting off the motor.
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These play only one record, not a stack. However, they, too, lower and lift the tone arm, returning it to the rest and turning off the motor.

Similar to automatic turntables exceptthat you manually lift the tone arm and place it in the lead-in groove atthe beginning of the record, usually with the aid of a cuing lever. When the record has finished playing, the tone arm automatically lifts and the unit shuts off.

You do everything manually, from turning the uniton throughturning it off. Some, but notall, models switch on the motor as you lift the tone arm. Most turntables come with a built-in tone arm but there are several models available that permit you to install a separate arm of your choice.

There are three common types of turntable drive motors. Induction and synchronous types have been used with good results for years. However, the speed of induction motors may vary with changes in the power line voltage, while synchronous motors may vary their speed if power line frequency should change. With "brownouts" still mentioned as a possibility in the States, these characteristics are something to keep in mind. Electronically controlled motors are the latest type. Special circuits monitor and adjust motor speed continuously for pinpoint accuracy regardless of minor changes in line voltage or frequency. This superior performance naturally carries a superior price.

There are also three basic types of drive systems. Direct drive, using a low-speed, electronically-controlled motor, is the latest method. The turntable platter itself is dlrectly attached to the motor and rotates with it. Wow, flutter and rumble are usually very low with such a system. Belt drive and idler drive are older methods, but each has proven satisfactory. Belt drive systems usually do a fine job of isolating motor noise from the turntable, but sooner or later belts must be replaced. Idler drive, which transmits powertothe plattervia rubber wheels, is still the most popular drive system.
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Both refer to unwanted variations in the speed of turntable rotation. Flutter is a relatively short-term variation and results in a fluttering sound, while wow involves somewhat longer-term changes.
The less of both, the better. Figures below 0.15 percent are acceptable, but most units today have 0.10 per cent or less flutter and wow.
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Low-frequency noise generated by the operation of the turntable is called rumble. As the name suggests, this may be perceived as a rumbling sound. Or, it may be of such a low frequency that it is inaudible. In the latter instance, however, it may create unusual movements of the speaker's cone, and thus interfere with the proper reproduction of other sounds. Look for a 45 dB or higher rumble figure. (Rumble figures may be given as a positive or negative number. Either way, the greater the figure itself, the less the rumble.)
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Opinions vary as to the importance of weight, but the most widely voiced belief is the heavier, the better. Others feel that weight is of little concern with today's sophisticated speed regulation and drive systems. As to the size, a 12-in. record is obviously more fully supported on a 12-in. (or larger) platter than on a smaller one.

The tone arm is a vital part of the total system, especially now with the increasing use of low mass cartridges operating at exceptionally low tracking forces. Most of today's tone arms offer features designed to allow for critical adjustments of cartridge overhang and height, vertical balance and horizontal balance (including anti-skate properties) to prevent the uneven wear of the inside walls of record grooves caused by the natural tendency of a pivoted arm to move toward the center of a rotating disc. A few manufacturers offer straight-line tracking or articulating arms which eliminate this kind of error.

The cartridge/stylus assembly converts the undulations or "wiggles" in the record groove into electrical signals which are then used by the rest of the system. If the output of your cartridge is distorted, the resulting sound will suffer regardless of how well the other parts of your sound system perform.

The job of the cartridge isn't an easy one. The undulations in a record groove physically correspond to the frequency of the recorded sound. That is, if a 5,000 Hz tone is recorded for one second, the stylus and cartridge must follow 5,000 undulations in one second to faithfully reproduce the original sound.

A cartridge's ability to accurately produce the electrical equivalent of the complex unduiations in a record is called trackability. It is usually expressed in terms of the highest velocity, for example, 20 centimeters per second (20 cm/sec), at which a cartridge/stylus can move at a particular frequency while maintaining accurate reproduction.

At present, not many manufacturers advertise their trackability figures, largely because the public is better acquainted with compliance, which indicates the ease with which the cartridge/stylus moves. Compliance figures are expressed in terms of the amount of movement in centimeters (cm) per unit of force (dyne) applied. A typical figure might appear as 25x10-6 cm/dyne. The higher the figure, the greater the compliance and the smaller the amount of force needed to move the stylus. As a rule, compliance should be at least 20-25x10-6 cm/dyne or higher.
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Refers to the downforce (in grams) that should be applied in order for the cartridge to do its job properly. Tracking force is usually given as a range, say from 1 to 1.5 grams.

In general, cartridges designed to track at higher downforces are physically better able to stand abuse, but produce somewhat more record wear. Lighter tracking cartridges cause less wear, but must be handled somewhat more carefully to prevent damage.

The better the turnable, the more satisfactorily it should handle a sensitive cartridge. Also keep in mind that multi-radial CD-4 styli, such as the Shibata, have a larger record groove contact area and hence can be tracked more heavily without harming your records.
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Most cartridges will respond to groove modulations over a range from 20-20k Hz. Since that represents the normal extremes encountered on most records, it is a satisfactory range. Of course, even wider response, say from 15-25kHz, is relatively common these days. With CD-4 cartridges, which must reproduce the high frequency carrier signal for the rear channels, frequency response upper limits of 45-50k Hz are necessary.

When choosing a cartridge, make sure its recommended tracking force is compatible with that of your tone arm. Some arms may not be able to properly handle cartridges designed to track at very light pressures. At best such a combination won't produce the kind of quality sound you paid for, and at worst it may damage your cartridge or records.
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The stylus of a cartridge is what was once commonly refered to as the needle. Virtually all top quality styli are diamond. There are three basic shapes of styli - spherical, elliptical and tri-radial. As a general rule an elliptical or "bi-radial" stylus will provide a better frequency response and less distortion than the spherical type. A cartridge with an elliptical stylus, however, must have a lighter tracking force to prevent record wear.

CD-4 disc reproduction requires not only the use of special cartridges and styli, but also special low-capacitance wiring. This is because the high frequencies involved are poorly conducted by normal wiring. Thus, if conventional cables are used the CD-4 carrier signals may be lost and with them the 4-channel effect. If you aren't ready for quad now, but think you might be soon, then keep low-capacitance wiring in mind.

Among the non-essential but useful features available are cuing controls for gentler, more accurate raising and lowering of the tone arm. Many of these devices eliminate potential damage resulting from dropped arms through the use of viscous damping. Another feature which may prove useful especially to musicians who wish to play along with their records, is variable speed control.
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As we mentioned earlier, a compact system consists of: a turntable of some sort, complete with tone arm and (in most cases) pickup cartridge; the necessary electronics, including preamplifier and power amplifier; and, speakers. Compact systems are available in stereo and quadrophonic models, with many stereo units designed for conversion to 4-channel with the addition of two more speakers.

Like the "record player" that you may have toyed with as a youngster, the modern compact systems asks little more than that you plug it in and switch it on. Despite this ease of operation the better compact systems offer excellent fidelity. You aren't limited to playing records, either. Most of the units in our listings include an AM/FM-stereo tuner and some also feature cassette or 8-track cartridge units.
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