Moving Magnet vs. Moving Iron
Printed From: Graham Slee Hifi System Components
Category: Turntable Audio
Forum Name: MM: Moving Magnet | MC: Moving Coil
Forum Description: Learn about the differences between moving magnet and moving coil cartridges here
URL: https://www.hifisystemcomponents.com/forum/forum_posts.asp?TID=104
Printed Date: 27 Mar 2026 at 2:11am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: Moving Magnet vs. Moving Iron
Posted By: Analog Kid
Subject: Moving Magnet vs. Moving Iron
Date Posted: 23 Mar 2008 at 2:07pm
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The internet is full of discussions comparing Moving Magnet and Moving Coil phonograph cartridges, but nobody seems to talk about the differences between Moving Magnet and Moving Iron cartridges. So between those two, which is better? And in what ways do they differ in terms of sound? Let me see if I understood this correctly: in a Moving Magnet type of cartridge, the coils are fixed and the magnets move, but in a Moving Iron cartridge, both the coils and the magnets are fixed, with the cantilever making a piece of iron move which then causes the magnets to induce a signal in the coils. Is this correct? Or did I misunderstand something? |
Replies:
Posted By: Analog Kid
Date Posted: 14 Apr 2008 at 4:52am
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Hello? Anyone? No one?  |
Posted By: Graham Slee
Date Posted: 14 Apr 2008 at 10:04am
I'm working round to a reply...
------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: Chivas
Date Posted: 13 Mar 2009 at 10:54am
| Can we expect a reply soon..? |
Posted By: Graham Slee
Date Posted: 13 Mar 2009 at 11:55am
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coming up....
------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: tg [RIP]
Date Posted: 14 Mar 2009 at 12:41am
| While you are waiting have a read of this - http://www.dagogo.com/OneCartridgeForAll-Part2-Decca.html |
Posted By: Graham Slee
Date Posted: 15 Mar 2009 at 3:24am
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OK, reply as promised... I don't have the historical dates but possibly around the 1940's phono cartridges were moving coil - yes moving coil. The development of small powerful magnets had not happened at that time so the coil being lighter, moved in sympathy with the stylus. However, the coils of these early MCs were quite big to get the number of ampere turns required to output the 10 milli-volts (mV, that's 0.01Volts) or so suitable for a "low-noise" valve phono input stage. At that time people were into directly connecting cartridges to amplifiers because matching-transformers were expensive and hi-fi meant high fidelity instead of "look at me I'm rich"... When magnet technology gave us the small powerful magnets required, the moving magnet cartridge happened and rapidly took over due to its lighter stylus load meaning it had a better frequency range. Then somebody decided to make the low output moving coil. I have heard it rumoured it was Joe Grado. Great idea in every single way apart from whoever it was didn't understand electronics - especially noise matching - all that well... So it needed a matching transformer - and hi-fi became a passtime of the rich - or "the ever so slightly overstretched"... I have never liked low output MC for that reason alone (the noise matching): I have heard so much boasting of -90dB input noise but would love it if they could show me them measuring it! The only way to make a MC stage without a transformer is to go all out for low noise and stifle the phase-response (you can't have your cake and eat it!) which makes MC sound "plodding". In fact some reviewers are so addicted that when they hear an MC stage that sounds exciting and refreshing they hate it... But hated as I am I keep trying. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: tg [RIP]
Date Posted: 15 Mar 2009 at 5:07am
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You know we love your work G - but the question I read was
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.....but nobody seems to talk about the differences between Moving Magnet and Moving Iron cartridges. So between those two, which is better? And in what ways do they differ in terms of sound?Posted By: Graham Slee
Date Posted: 15 Mar 2009 at 1:21pm
Must be my age... I'll let Gary D. Markowitz explain (whomever he is) "it [the Moving Iron] has two small pieces of iron attached to the cantilever perpendicular to the record grooves. They are situated between the magnet and the coil, and the motion of the iron in the magnet's field induces AC current in the coil. One of the advantages of this design is that the moving iron can be lighter than the magnet on a moving magnet design, allowing more powerful magnets and larger coils to be used than a standard moving coil cartridge" Simple? So you can have more windings than a low output MC but less than a MM so you don't end up with such a high inductance limiting the frequency response top end. Great idea! But what you can get is a difficult to control oscillation due to the inductance: the phono stage designer may have accounted for every possible permutation of MC and MM cartridge, but then the MI is thrown at him... Which shows phono stages and headphone amps are very similar? One has to deal with a range of transducers all having their own little foibles and demanding their own matching characteristics at the input - the other at the output. And then folk ask when will I do a pre and power amp? As soon as I can escape having to cover for all these transducers... EDIT: forgot the smiley marks (age again???)       arrange as you feel fit ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |