Moving Magnet vs. Moving Coil


MM 101

There are two primary methods a modern cartridge uses to generate current. These are moving magnet (MM) and moving coil (MC) configurations. Many moving coil cartridges come in high and low output versions. In order to better understand the differences between the two it is necessary to briefly discuss methods of generating electricity, as well as provide you, the reader, with an amusing anecdote from my youth.

Let's travel back in time together to science class. My 8th grade science teacher delighted in demonstrating for us a small hand-cranked generator. In hindsight his methods were quite masochistic. He would line us up and eloquently explain the wonders of electricity by giving each of us a mild shock. After all of our fingers were zapped, and he had briefly made each of us accountable for being disinterested in science class, our status quo arrangement of politely ignoring one another resumed. I did, however, develop a rudimentary knowledge of electricity, as well as a distrust of science teachers that I retain to this day.

Basically, moving magnet cartridges work the same way as that (or any other generator). By moving a magnet between copper coils, a small amount of voltage is created. It breaks down like this:

As your stylus tracks the groove of a record, it responds to the contours therein (as well as to air- and vibration-borne resonance). Movement of the stylus dictates movement of the magnet, which is seated near two fixed coils (left and right channels), as most records are cut to produce two separate signals. The movement of the magnet near the coils generates a small amount of voltage, which travels from your cartridge to an amplifier and suddenly you're listening to Paul Stanley espousing his desire to "rock and roll all night, and party ev-er-y day."

Moving magnet cartridges tend to produce lush, mellow sound. They are available in a variety of shapes, sizes and levels of quality. Most MM cartridges have replaceable styli. Their high voltage output, variety, and the availability of stylus replacements make moving magnet cartridges a great choice for the beginner and audiophile alike.

Right about now your probably asking, "Dude, if moving magnet cartridges are so great then why do they make Moving Coil Cartridges too?"

For you, gentle reader, I will attempt to explain...

MC 101

Moving Coil (MC) cartridges work in a similar way to MM cartridges. The primary difference being that as your stylus tracks, it 'moves' tiny wire coils around a magnet. Many audiophiles prefer moving coil setups. MC cartridges tend to display better tonality, transparency, imaging, and also tend to create less distortion than their MM counterparts.

A moving coil setup requires much more consideration with your system, as well as a familiarity with audio component setup. Moving coil cartridges are not always the best idea for a beginner. Many MC cartridges will not work with phono preamps designed for MM cartridges. Modern amps and receivers often do not have an input for turntables (usually labeled "PHONO"). If your amplifier does not have this feature you will need an outboard phono preamp to boost the cartridge's signal, to be connected to an available line-level input. If your amplifier does have this section, you will need to know if it is configured for MM or MC (usually MM). Most often, moving coil cartridges require an outboard phono preamp.

Many manufactures produce high and low output versions of the same cartridge. Dynavector, for example, produces their heralded 20x series in both varieties (2.8mV and 0.3mV). Except for the output and a couple related specs, these are the same cartridge. Other manufactures produce both high and low output cartridges that are dramatically different from one another. High output MC cartridges can usually be used with pre-amps configured for MM setups.

If you have no existing phono preamp, your options are limitless. You will simply need a versatile preamp capable of meeting your cartridge's electrical demands, whether it be MM or MC. If you have an existing moving magnet preamp (separate from or integrated into your receiver), or your budget precludes an MC preamp, you can chose among any MM cartridge or a high output MC, and you should be good to go. If you are determined to run a low output cartridge but don't want to change your existing MM preamp; step-up transformers are available and in some cases, preferable. A step-up transformer takes an MC signal and boosts/equalizes it so it's ready for a more standardized MM phonostage.

If you're still not sure what cartridge is right for you, call or email us; our staff will be happy to advise you.