Moving Magnet vs Moving Coil Cartridges

After some umming and arring you have decided to join the ever growing group of people that is giving vinyl a renewed place in their home. No longer is it solely appealing to the audiophile elite that is willing to fork out many thousands of dollars for a high-end set-up. To more and more people, there is appeal in casually having a turntable alongside their audio streamer, both used in very different situations, both providing pleasure in audio. 

But once you start your research, you bump into options and decisions, you weren’t even aware you were going to face. One of them is the choice of a Moving Magnet (MM) versus a Moving Coil (MC) phono cartridge. 

Although the outcome for both is the same (creating audio from a records groves), both designs are very different and so are their characteristics. Time for us to have a dig into the world of phono cartridges. 

 A good cartridge?

To understand the difference between a Moving Magnet (MM) and a Moving Coil (MC) cartridge, we need to go back to the Stylus (the needle) of a turntable and the job it performs.

In a nutshell, as you’re playing a record, the stylus of a record player travels through the hills and valleys on the vinyl as you play the record. Every tiny movement, whether horizontally or vertically (mechanical energy) represents music. It’s the nearby coil and magnets job to translate this reading into electrical energy. And finally this audio signal is then sent through the wires leading to your home stereo equipment or speakers. The result is music!

So, while It’s easy enough to understand that the job of a phono cartridge is to convert one form of energy into another, it’s also important it does this as accurately as possible so that the original sound of the performance is retained.

Navigating the rugged terrain of a record groove is no easy task. The rapidly changing amplitude of the signal that is cut into the groove requires a generator that can react very quickly to these hills and valleys, yet stay firmly planted in the groove at the same time. A  good stylus assembly is light in weight and therefore is able to respond quickly as well as keep record wear to a minimum, But at the same time, it also needs to be stiff  to quickly and accurately transmit the vibrations from the stylus tip to the generator with as little resonance and turntable rumble as possible.

It’ll be no surprise that this is no easy job and the way the ‘reading’ of the grooves happens, as well as the way the mechanical energy is translated by the coil and magnets has a lot of impact on the performance of a turntable. (There are some other things like stylus shape that are important in this respect as well, but we’ll stick to the topic of MM vs MC in this instance.)

Which brings us to the difference between a moving magnet (MM) or a moving coil (MC) cartridge.

MM vs MC

So how are Moving Magnet and Moving Coil cartridges different?

We’ll start off by saying that below explanation is a generalisation and that there are good and not so good cartridges in the MM camp and in the MC camp. So with that out of the way…

All turntable phono cartridges have magnets and coils. They are the vital parts in converting mechanical energy into electrical energy . The main difference between an MM and an MC cartridge is where they are located with respect to the stylus.

In a few words and without getting overly technical, a moving magnet (MM) cartridge accomplishes the conversion by connecting the vibrating needle to a set of magnets (hence ‘Moving Magnet’) that then vibrate in close proximity to coiled wire. A moving coil (MC) on the other hand does it the other way around: it has the needle vibrate coiled wire in close proximity to fixed magnets. While it may sound like overly detailed nitty-gritty, it does have significant effect on the characteristics of each of the cartridges.

Because of the lay-out and the way the conversion happens, a moving magnet cartridge is ‘high-output delivery’ or delivering a reasonably ‘strong’ signal. This fact is directly responsible for some of the advantages and disadvantages of a MM cartridge.

On the up, it means a MM cartridge is relatively cheap to manufacture and easy and no-fuss in its use: it is compatible with almost any phono input on a stereo component and it also means that the stylus can be replaced without having to purchase an entire new cartridge in case of wear and tear or breakage. In other words, it’s easier on the wallet.

The downside is that a the magnets in a moving magnet cartridge tend to have higher weight. The result of that is that the stylus can’t move as quickly over the record, which inhibits its ability to track the subtle changes within the groove’s surface. Bottomline, this has effect on the performance .

In the same way the magnets in a MM cartridge create extra weight, The  small and light-weight coils give the stylus more agility when navigating the constantly changing record grooves. This results in greater detail, improved accuracy, and less distortion of sound.

But the ups of the MM cartridge are also the downsides of the MC cartridge: Because of the a smaller voltage created when using a MC cartridge (about a 1/10 to 1/100 the amount of energy compared to a MM), it is a lot fussier and more delicate.

This means it is also far more susceptible to system hiss/hum issues. Because the MC is more sensitive to record vibrations, it follows that it is also more sensitive to other noise as well. Because of that, MC cartridges can offer a significant upgrade in performance but the rest of your system must also be up to the task.

A turntable with an MC cartridge will require a step-up from the more basic MM amplification. An MC specific phono stage creates extra gain provided by a secondary preamplifier or ‘step-up transformer’ (SUT). If your phono stage allows for that, there will be a set of dedicated phono inputs labelled “MC”.(Note: there are exceptions to this rule as there is such a thing as a ‘high-output MC cartridge’-more on that later).

Talking fussy and delicate, you cannot remove the stylus on a moving coil cartridge. So if your stylus has worn out or is broken, you need to get a re-tip repair or it’s off to the shop for a new cartridge.

Because both types of cartridges are so different, most turntables and phono amps will be either MM or MC specific and are not interchangeable, although there are some exceptions to that rule. .

So which one? 

Is one better than the other?

Nope, both MM and MC cartridges and turntables can be excellent performers and are offered in a range of prices, shapes, sizes, and levels of quality.

You will find that most turntables are designed for a MM cartridge. For a person just starting out spinning vinyl, a MM set-up is the way to go. It’s cheaper, it’s compatible with almost any phono input and it’s more robust.  If properly done, it will not give away anything in terms of musical performance or enjoyment and it can be a very viable option for any serious audiophile.

But because an MC set-up has the ability to go that one step further, it’s often the choice of dedicated audiophiles that are happy to spend the extra money on the extra amplification as well as the higher cost of the MC cartridge itself.

We mentioned high output MC cartridges earlier on. More powerful magnets and finer control over the winding process have resulted in higher output MC cartridges. This is an attempt to combine the best of both topologies into one. The high output MC design uses a larger coil and more powerful magnets. The downside is that this also increases weight and as a result reduces dynamics. It will come as no surprise that there is a feeling in the audio community that high output MC designs are a step in the wrong direction and come with all the same inherent limitations of MM designs that low output MC designs neatly avoid. But then again, some people swear by high output MC cartridges.

Finally, we also would like to point out that MM and MC cartridges are the two main types, but you will also find some reference to for instance Moving Iron (MI) cartridges. This type is similar to a MM cartridge but replaces the magnet with a (lighter) moving piece of iron at the end of the cantilever.

Note: The above photo is the stylus from the ELAC Miracord 70, which is now on demo in our showroom.  We also have the Audio-Technica AT-LP-5, the Klipsch R-15-PM plug and play powered set-up and several of the Edwards Audio turntables for you to check out. You can watch the unboxing of the ELAC Miracord 70 turntable here.

Source: Audio-Technica, LiIfewire, Stereophile, Perreaux, home theatre hifi, ELAC. Above MM vs MC schedule is from ‘Colored Vinyl Records’.