Several phono pickup manufacturers are offering new versions of the cartridge known as "moving coil." This type of pickup has long been part of the hi-fi scene, albeit a minor one since over the years it was overshadowed by the more popular moving-magnet type. While the moving-coil pickup is capable of superb response, it typically furnishes a low signal output voltage - too low for direct plug-in to the magnetic-phono inputs on most amplifiers or receivers.

To overcome this, m-c pickups usually are offered with small transformers to boost their signal to a level suitable for connecting to a normal phono input. Alternatively, the use of a "pre-preamp" or "head amplifier" can provide the needed signal boost. Either way, of course, involves a more complex and costlier setup for playing records. Another drawback of the m-c pickup is the need to return it to the factory for stylus replacement, since the construction of this cartridge generally preludes having its stylus removable and replaceable by the owner.

These problems notwithstanding, the m-c pickup seems to be enjoying a rebirth these days with several Japanese firms - such as Nakamichi, Denon, Supex, Fidelity Research - joining Ortofon (probably the granddaddy of moving-coil pickups) offering new models. At least one of these new m-c advocates, Osawa, claims to have a moving-coil model with high enough output to permit feeding its signal directly into the normal magnetic phono input. The Osawa version also is said to permit user replacement of the stylus.

Another aspect to the m-c pickup has received little attention, but is the sort of thing that logically would concern the buyer of something as esoteric as a moving-coil pickup in the first place. That concerns the tone-arm in which it is to be used.

Vis-a-vis other magnetic pickups the m-c types as a class are heavier and have lower compliance. Their tracking forces are a little higher too. However, the arm that has evolved in the past 15 or so years was developed primarily to suit those other magnetic types and is typically a low-mass design eminently suited for ultra-high compliance pickups. Such an arm, fitted with a moving-coil pickup, may produce bass resonances that can muddy up the low-end response. Some king of, external "damping" could be added to such a setup but it is only begging the question, acoustically speaking, and it adds even more to the cost and complexity of the installation.

At least one m-c manufacturer - Fidelity Research - recognizes this problem and frankly recommends using its m-c cartridge in a high-mass arm, which of course is not likely to be found on your typical record-player ensemble no matter how excellent it may be in other respects.

This suggests that the audio enthusiast attracted to the m-c pickup may not get exactly the kind of performance anticipated by merely substituting such a cartridge for the conventional one. Chances are, a new tone-arm would be required too, and this device could be chosen from among the separate arms being offered by a few sources. More cost and more complexity when adding such an arm to an existing turntable, but many aficionados feel it's worth it.