Moving Magnet vs Moving Coil Phono Cartridges – How to Choose

Moving Magnet vs Moving Coil: Introduction

Moving Magnet and Moving Coil cartridges work on the same basic principle: mechanical vibrations are converted into an electrical signal. In both Moving Magnet and Moving Coil designs, the cartridge cantilever holds a diamond stylus. This stylus tracks the record groove on one end, and transfers the vibrations to the generator inside the cartridge body.

The generator, may it be Moving Magnet or Moving Coil design, works according to Faraday’s first law of electromagnetic induction. This law states that whenever a conductor is placed in a varying magnetic field, an electrical voltage is induced in that conductor.

In both cartridge designs, a coil of wire is placed in the magnetic field of a permanent magnet.

End of the similarities between Moving Coil and Moving Magnet designs.

Now let’s see their distinctions:

• In a Moving Magnet design, the coil is stationary and the small magnet is attached to the vibrating cantilever.
• Inversely, in a Moving Coil cartridge, the magnet is stationary and the coil is attached to the vibrating cantilever.

We now know that Moving Magnet and Moving Coil phono cartridge designs are 2 methods to get the same result. But does it make a big difference whether you move the coil close to a fixed magnet or vice versa?

Well yes, and here are the 3 things you need to know to better understand why:

1. High vs Low Moving Mass

The first thing to understand is the notion of moving mass. In a Moving Magnet cartridge, the moving part is the stylus / cantilever / magnet assembly. In a MC cartridge, it is the stylus / cantilever / coil assembly.

The coil windings of a Moving Coil cartridge are often lighter than the magnet of their Moving Magnet counterparts. We therefore say that Moving Magnet cartridges have a higher moving mass than Moving Coil cartridges.

The larger moving mass of Moving Magnet cartridges implies that their stylus has more inertia than the stylus of Moving Coil cartridges while tracking the record groove. In other words, the stylus of a Moving Magnet cartridge cannot react as quickly over the record, limiting its capacity to track subtle changes in the groove’s surface. This is therefore where MC cartridges tend to have a first performance advantage. Sonically, Moving Coil cartridges offer a more detailed resolution, and better dynamics.

Le Son designs several moving coil cartridges, including the LS10 MKII and the SL1 MKII, built around these same priorities of low moving mass, musical precision, and system coherence.

2. High vs Low Inductance

The second key difference between the 2 designs is that of inductance. As Moving Coil cartridges have smaller coils than Moving Magnet cartridges, we can say that Moving Coil cartridges have a lower inductance. Why is this important? Because the inductance of the cartridge, the capacitance of the phono cable, and the resistance & capacitance of the phono preamp input altogether form a harmonic oscillator circuit, also called RLC circuit.

This kind of circuit has a ringing resonance at a certain frequency, and a steep roll-off of frequencies above the resonant point, also called low-pass filter. The lower the inductance of the coil is, the higher the frequency of the resonance is, and vice versa. So for Moving Coil cartridges, the resonant frequency will be way up in the ultrasonic range, and changes of cable or phono input capacitance won’t have much of an audible impact. The ultrasonic ringing can also be damped by loading the cartridge with the appropriate resistance at phono input level.

With Moving Magnet cartridges, the higher inductance and capacitance will have an impact on the frequency response of the system in the audible range. For good Moving Magnet cartridges, the resonant frequency often falls somewhere in the top two octaves of the audible range, with all frequencies above that being rolled-off.

In summary, Moving Coil cartridges have a lower inductance than MM cartridges, so their frequency response is flatter and more extended. In comparison, Moving Magnet cartridges tend to have a less even frequency response, with the top frequencies rolled off.

For stereo cartridges, smaller coils also mean less crosstalk between them. As a result, MC cartridges tend to have better channel separation (+10dB or more) than MM cartridges. It translates acoustically into better stereo imaging.

3. High vs Low Output

The third crucial distinction is the output each cartridge produces. The output is measured in millivolts (mV), and largely depends on the size of the coils. We now know that MM cartridges have larger coils than their MC counterparts. As a result, they have a higher output (typically 3 to 7 mV), and can be connected to the standard phono inputs of a stereo amplifier or receiver. Easy and cost effective.

For MC cartridges and their very small coils, it is a different story. Their output level is much lower, typically between 0.2 to 0.6 mV.  Therefore they need an extra gain in the phono preamp of 20 to 26dB. This extra gain can be achieved with a MC step-up transformer (SUT) or a MC Phono Preamp. For a deeper understanding of this topic, see our guide to MC step-up transformers.

In summary, Moving Magnet cartridges and their high output are much easier to work with and just require a MM Phono Stage. MC cartridges require a MC Preamp, or a step-up transformer between the turntable and the MM Preamp. The extra equipment can be very costly and need to be taken into account when choosing between the 2 types of phono cartridge.

Moving Magnet vs Moving Coil: Which should you choose?

By now the differences may look one directional, with moving coil ahead on resolution, frequency response, and channel separation. On paper, it often is. In a real system, the honest answer is more nuanced.

Moving coil rewards a system that can resolve what it offers, and a cartridge well matched to your tonearm and phono stage. A moving coil chosen too early, before the rest of the chain or the budget is ready, can gain detail on some records while giving up some of the coherence and ease a well set up moving magnet delivers on others. The result is sometimes a genuine step up, and sometimes simply a different presentation.

So the more useful question is not which design wins, but whether the move is a real step up in your system.

Our recommendations:

• A good moving magnet, properly aligned and fitted with a quality stylus, remains a deeply musical choice and an excellent way to learn what you value before investing further. For many listeners it is a destination, not a stepping stone.
• Moving coil makes the most sense when your tonearm, phono stage, and listening priorities are ready to reveal its strengths, and when the cartridge itself is well matched rather than chosen for the label alone.
• The extra cost of moving coil, a MC phono stage or step-up transformer and often a more careful setup, belongs in the decision from the start.

If you are weighing this step, we are glad to advise on the match for your system before any decision, and every Le Son cartridge includes a 60-day home evaluation so you can confirm the result in your own room.