A moving magnet or MM cartridge has a heavy iron(ferrous) magnet on on the end of the cantilever that’s surrounded by coils. And a moving coil or MC cartridge has a light coil on the end of the cantilever that’s surrounded by coils. MC generally delivers higher quality audio, but is more costly because its signal needs to be amplifed with an extra component.
Table of Contents
Introduction to MM vs MC
If you’re in the mood to read an entire article I’d like to point you to the YouTube video at the end of this article. This video will also give you a good impression about what I’m discussing in the following paragraphs. If you don’t have time to watch a 10 minute video, then you can scan this article or just read the conclusion. But of course I hope you read everything and leave some positive and negative feedback in the comments.
Let’s get into the actual topic of this article now. Moving Magnet vs Moving Coil cartridges. These are both techniques that create an audio channel from record grooves using electromagnetic induction. They just have their own application of this science which leaves both of them with their own pro and con. Let’s dive in.
Electromagnetic Induction
In the year of 1831, Michael Faraday discovered that when you change a magnetic field through a coil it induces a voltage or current. So when a magnet is sitting still within a coil no current is created, but when the magnet is moving a current is created in the coil. This is a way to convert motion into a current. This technology is what is powering all of our cities and factories. But it is also used on a much smaller scale. We use it for playing music.
MM – Moving Magnet
A moving magnet cartridge uses electromagnetic induction to create a stereo channel. Let’s start at the stylus. The stylus is the small point made from a hard material like diamond that moves through record grooves to read the physically recorded audio. The stylus is attached to the cantilever which is really just a shaft which in the case of an MM cartridge has a magnet at the end of it.
Now we’ve come to the part where the motion from the stylus and the record grooves, passed through the cantilever to the magnet is turned into an audio channel. The electromagnetic induction technology is used here. The magnet is surrounded by two coils. And based on the direction of movement of the stylus > cantilever > magnet a specific current is produced. So the record grooves imply a frequency which can be used by speakers to play audio.
MC – Moving Coil
If you understand MM then you’ll also understand MC. Because it’s really just exactly the except the electromagnetic induction arrangement is reversed. Now at the end of the cantilever a small light coil is attached which is surrounded by two magnets. Again the motion from the stylus and record grooves create the audio channel.
MM vs MC
So to quickly summarize the last two segments. A moving magnet cartridge has a heavy iron(ferrous) magnet on on the end of the cantilever that’s surrounded by coils. And a moving coil cartridge has a light coil on the end of the cantilever that’s surrounded by coils.
Since the weight on the end of the cantilever influences the delicacy of the groove tracking an MC cartridge has the upper hand over the MM. The downside of this is that the electromagnectic induction application of the MC leaves it with a lower voltage than the MM application, which can be 20 to 30 times stronger. This means that an MC cartridge stream would need to be amplified before it becomes usable. This is done with headamps or preamps for example. This isn’t required for an MM cartridge.
What this means is that an MC cartridge will generally have more delicate tracking, but will be more expensive.
Conclusion
So to conclude this article. Both MM and MC use electromagnetic induction, but use their own variation. The MC variation leaves it with more delicate record groove tracking, but also with a higher price.
Hopefully this was useful to you. I’d also love it if you checked out my educational articles like this one. Or if you’re interested in buying a new record player then you can check out my reviews & top lists.
Sources
- Tsugio Ito; Shigeru Fujita, U.S. Patent 4,597,071, Jun. 24, 1986, from https://patentimages.storage.googleapis.com/72/bb/bc/4c264141f34de0/US4597071.pdf
- Masanobu Cho, U.S. Patent 3,679,843, July 25, 1972, from https://patentimages.storage.googleapis.com/d4/84/fe/a9db8cd9d17f94/US3679843.pdf
- Audio-Technica, “What Are The Differences Between Moving Magnet And Moving Coil Phono Cartidges?”, January 23, 2018, from https://www.audio-technica.com
- Paul McGowan, “Moving Magnet vs Moving Coil”, July 14, 2019, from https://www.psaudio.com/
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