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The difference between Moving Magnet / Moving Coil / Moving Iron Cartridges


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Turntables are and remain very popular. More and more turntables are being sold and the production numbers of records are increasing year by year.  With this information I would like to give the newbies who are new to turntables and cartridges a basis to understand the technical differences between MM / MC / MI ( MP )  cartridges.



MM = Moving Magnet 


Nowadays the probably most common pick-up technology and especially in the entry level area dominating. At the upper end of the nail carrier there is a magent, which moves excited by the movement of the needle in the groove between two coils. Physically, the MM pickup is an electromagnetic transducer: The change in flux in the magnetic circuit is coupled to the inhomogeneity of the magnetic field - the greater this is, the greater the signal. The MM-principle delivers comparatively high signal voltages, so that after the usual equalizer preamplifier a quite simple preamplification with 47kOhm input resistance is sufficient. Until the end of the 1990s, and again occasionally today, many HiFi full amplifiers were equipped with a phono input suitable for MM systems.




MC = Moving Coil  


Mechanically, the MC design is similar to an MM system, except that here a coil is located at the end of the needle carrier and the magnet(s) are fixed. Moving Coil is therefore an electrodynamic transducer that delivers relatively low signal voltages and therefore requires a very high-quality and low-noise additional pre-amplification. Phono preamps suitable for MC have - usually adjustable - input impedances between 20 and 1000 ohms. Many common phono preamps can be switched between MC and MM operation.The advantages of the MC principle are - generally speaking - the potentially lower weight of the coil attached to the needle carrier. Since there is no need to move a heavy magnet back and forth, more detailed scanning is possible. MC pickups are usually more expensive than MM systems and also place higher demands on the rest of the reproduction chain. In terms of sound quality they are usually (not always) superior to a moving magnet system.




MI = Moving Iron /  MP = Moving Permalloy


The third magnetic scanning principle is - wrongly - often overlooked. In the high-end segment e.g. Soundsmith from the USA or Goldring from England are well-known advocates of the MI principle; the Japanese traditional manufacturer Nagaoka places its MP pickups in the lower and middle price segment as a sonic superior alternative to MM systems. As with the MM principle, here the coils are permanently mounted. At the end of the nail carrier, however, there is no heavy magnet but only a tiny piece of a magnetic metal (either "iron" or so-called mu-metal, "permalloy"). Depending on the pick-up, this piece of metal is even lighter than the coil of an MC pick-up, which can result in an even better scanning of the record groove. MI- and MP-pickups are also electromagnetic transducers, therefore they deliver high signal voltages and can be operated at the MM-input of the (pre-)amplifier.









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B&O used a variant of the moving iron called micro moving cross, that had a cruciform piece of ferrous material that the stylus moved over the four poles of the coils and fixed magnet. It was most famously used in their SP-12 line. I had a SP-12A in my vinyl days and I loved it. It was slightly rolled off at the top, but with bright speakers it sounded very neutral. The test reports of the time noted its exceptionally low distortion.

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11 hours ago, baron167 said:

What is this sorcery? And why does MM and MC both mean Moving Magnet? And while I'm at it, what cantilever materials and stylus types are the best for a budget-minded college student?

Sent from my iPhone using Tapatalk

Oops, I made a typographical error, sorry, I just corrected it.

Nagaoka MP-110 very balanced sounding cartridge with elliptical diamond. This MI system scans very well, sounds pleasant with good recordings. Very insensitive to scratches and dirt - therefore also very good for older records!


Nagaoka MP-110


or see Grado Pick ups ....



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Moving coil, especially low-output,  is in a different world from MM because of the much greater demands placed on electronics and associated equipment by LOMCs on preamps and electronics, by greater gain differences between models, and greater clarity and transparency from good moving coils.  These considerations can wash through the choices made through your entire system! LOMCs have a much greater range of gain choices than MM, which can be very difficult to deal with and require more careful matching to maximize benefits and minimize noise.  Better turntables and tonearms will show up more with a more transparent cartridge.  A system's cost may be greater with LOMCs for these reasons.


It may be best to purchase from those with active experience in selling and putting together systems.  Be sure to listen as much as possible before buying if you can.  Component synergy can make a real difference in your system.


The three components of LP player quality -- turntable, tonearm, and cartridge -- all need to be considered.  Tonearms have been a tad underrepresented in this discussion so far, though there may be a little less to say about them, but tonearm quality should not be underrated in your decisions.


 -- Larry

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I fully agree with you in your line of thought. The total package containing of TT, tonearm, cartridge and phono stage is crucial. Certainly Benz Micro Glider, Lyra Oleos / Skala, Well Tempered Kauri or Koetsu Urushi and other cartridges are considered to be absolute high-end top class. But they also cost between $ 1500 and $ 4.000. For TT's in this league with tonearm and corresponding phono stage, $ 10.000 is quickly spent.


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19 minutes ago, MC39693 said:

Direct drive vs belt drive vs idler? Thinking of getting back to vinyl after 12 year absence... too many choices! 

These are also important facts to consider. Belt-driven TT's and Idler driven TT's have abrasion, direct-drive TT's don´t, but it is said that the platter is not optimally decoupled from the chassis. As in the whole audio technology with all its available components, everyone has to decide for himself and is obliged to his own demands and needs.

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Did you mention that moving coil cartridges generally have non-replaceable stylus's?   ...I just bought a new turntable (Technics SL-1210GAE) and a new cartridge (AT VM760SLC).  ..I considered a MC cartridge but opted for a MC instead b/c the stylus can be replaced.

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Peter Pritchard is the inventor of the Moving Iron pickup.






Peter Pritchard founded Audio Dynamics Corporation in New Milford, CT in the early 1960s. His original ADC-1 (moving mass: 0.6 mg, needle compliance 20x10-6cm/dyn in all directions, contact pressure : 1 pond or less on top of top tonearms) was a groundbreaking product. In fact, all ADC pickups are characterized by extremely high needle compliance and low contact forces, and he followed this approach in a number of successful designs including the well-known ADC-10, ADC-25 and XLM systems. They were all based on his "induced magnet principle", which was derived from the older GE variable compliance systems that were used as affordable magnetic pickups in the 1950s.Without him the record would certainly not have developed so rapidly. His designs have influenced all others significantly: from Audio Technica to Ortofon. The most famous "pirate copy" has managed to survive until today: The Nagaoka MP500 is based on his ingenious ADC 10E. At General Electric, as a young engineer for Western Electric in 1956, who had already pressed the first modern stereo record, he was allowed to help the world's first magnetic stereo pickup, the GE VR22. He said goodbye to it in 1984 with the Sonus PME .5 LC



ADC 1 Cartridge


Design factors.


How to design a good pickup ? What are the parameters ? First, says Pritchard, the basic design principle is not critical to the final result. You can use a moving coil, a moving armature or something more exotic. The choice boils down to economic factors and simple design and manufacture. The biggest problem, says Pritchard, is how to accurately transfer the movement of the tip to the generating element. It is particularly difficult to transfer really all movements. In this respect, the ideal would be a massless, infinitely rigid boom-anchor system. Since the ideal does not exist, system manufacturers must deal with resonances. One possibility is to taper the cantilever conically. This suppresses fundamental cantilever resonances, but not higher order harmonics. Instead, Sonus decides to make the cantilever as short and light as possible. This also helps to reduce the overall mass of the moving parts. Each mass becomes a storage point for resonances. If the cantilever is long, nodes of oscillation are formed and the actual pivot point of the boom anchor starts to wander, maybe up to 10µ or so. If you keep the cantilever short, very little movement is wasted by torsion. The mass of the armature is kept low by using very thin, magnetically permeable material and by keeping the armature short. The suspension system and the armature have square cross-sections to keep the pivot point firmly in position and to suppress torsional movements. Sonus aimed for perfect symmetry of the moving parts. This contributes to a good separation of transients and a high channel separation that reaches the limit of the scanning range. The production systems are not as good as the laboratory models in this respect, but the production models must also have sufficient distance from the record when playing normal records. A useful feature of the Sonus' electrical design is its low impedance. The inductance is about 100 millihenry and the resistance is 300 ohms. This makes it easy to adjust the system and preamplifier, and also helps when using the Sonus Blue Label for CD-4. Pritchard also explained that it is almost impossible to reduce the mass with a bare diamond. With such needles, the diamond is secured by a very thin sliver of diamond extending through the boom shaft where it is secured with something like epoxy cement. If not enough cement is used, the pin in the shaft will wobble, and if enough is used, the mass advantage is lost. The Sonus approach is to connect the tip with a tiny piece of steel. The steel can be easily anchored to the shaft without increasing the mass significantly.




Pritchard believes that you really can't be sure what kind of distortion is present in pickups because it's difficult to tell how good the test recording is. A cleanly recorded medium frequency sine wave can be reproduced at 0.1% to 0.2% THD. What distortion is present is mainly due to geometry and is random in nature, so it is not displayed as an even-order harmonic. IM tests do not say much either, as they consider sum and difference products. In addition, visual spectrum analyzers do not say much because the distortion is (again) mostly temporary. According to Prtichard, the best choice to find a distortion of the scanner is an oscilloscope and a trained eye. Some hysteresis distortion is inherent in designs with a moving armature, but can be minimized. The moving armature is charged to the saturation point. When it is slightly less than saturated, the flux density in the armature changes as it moves towards and away from the pole pieces and the charging magnet, especially at high speeds. In the Sonus, the problem has been solved by using a very strong charging magnet with a short armature and by placing the magnet above the pivot point so that the armature is completely enveloped in the magnetic field and its position relative to the field remains virtually unchanged. A side effect is that the magnet does not mechanically bias the scanner.


Do stylus suspensions destroy themselves?


Well, they are known to fail, but as far as Pritchard can tell, stories about dissolving materials are not true. If the suspension collapses, it's most likely because something has come loose in the system. Cantilevers, on the other hand, deteriorate. They are usually made of very thin aluminum and are only protected by the aluminum oxide that forms on the outside. The shaft is only a thousandth of an inch thick, and it can corrode. ADC solved the problem of the cantilever, which consisted of a cantilever and anchor made of different metals and between which an electrolytic reaction occurred. Sonus uses a plastic barrier between the cantilever and the anchor.


Peter Pritchard has died on august 23rd 2011. RIP




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9 minutes ago, ODS123 said:

Did you mention that moving coil cartridges generally have non-replaceable stylus's?   ...I just bought a new turntable (Technics SL-1210GAE) and a new cartridge (AT VM760SLC).  ..I considered a MC cartridge but opted for a MC instead b/c the stylus can be replaced.

This is correct, the needles can only be changed on MM and MI pickups. An alternative is the so-called " Retipping " . These are specialists who have the know-how to exchange the diamonds on the needle carrier or even to install the needle carrier in the moving coil system.

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5 minutes ago, RandyH000 said:

you can replace the stylus  on a MC cartridge ---they replace the entire tip in specialized shops -----and just as good if not superior to the original ----figure about 1k$ or more -

It's not that expensive. You can also update the needles of a moving coil pickup, e.g. replace an elliptical diamond with a so-called Shibata needle cut diamond.

With the needle cuts we distinguish as follows :


The spherical round cut is again the simplest form (- but also the one which later on caused the least problems in handling).This is followed by the elliptical (oval) cut and then a series of special cuts, all of which follow the ideal of the slimmest possible, but large-surface grooving. Known names of these special cuts are van den Hul, Gyger, Shibata or Fine Line. In high-end design, these diamonds are also brought into an extremely small (short) design to save weight and minimize rotation of the elastically suspended needle carrier. Naked diamonds with elaborate polishing are most durable. With well-tended plates and correct adjustment, operating times of 2000 hours and more are possible. Whoever listens to an hour a day can therefore enjoy his records for about six years.


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1 hour ago, RandyH000 said:

The sky's the limit here , there are TT worth 50k$ ---------less than 10k$ gets you a Linn LP12 which is very-very  good -

Transrotor Artus FMD Plattenspieler | Plattenspieler ...

$ 125.000 Transrotor


Der teuerste Plattenspieler der Welt | messtec drives Automation

$ 500.000  Dereneville VPM


Wo ein Plattenspieler 200.000 Euro kosten darf - WELT


$ 200.000 Transrotor




$ 18.000 Technics SL 1000 R

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