B&O MMC 20CL Cartridge Question

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mefistofelez

Member
Joined 2002
Greetings all,

I came to a possession of a turntable with the above-identified cartridge. When looking for the technology (MM or MC), it seems to be neither, is is described as a "moving magnetic cross" or a "moving iron cartridge" whatever does that mean.

The question is, what phono-preamplifier do I need? Any DIY recommendation?

Kindest regards,

M
 
Galu

Galu

Member
Joined 2018
mefistofelez said:
"moving iron cartridge" whatever does that mean.
Click to expand...

There's a description of the moving micro cross design in this article: https://www.stereophile.com/phonocartridges/408sound/index.html

"Moving-iron designs ... use stationary coils and magnets and a small piece of "moving iron." In the original B&O design, what moves is a cross-shaped piece of ultra-low-mass, high-purity iron attached to a soft elastomer damper stabilized in a plastic frame. The iron also incorporates a minuscule tube into which the cantilever is inserted. Each arm of the iron cross is associated with a fixed-coil/magnet structure and as the cantilever moves, it varies the distances between the four arms of the iron cross and the four fixed-coil/magnets, thus inducing tiny voltages within the coils. The advantages of this arrangement include ultra-low moving mass, even compared to an MC design; relatively high output (because the stationary magnet/coil structure can be made large); high suspension compliance; and low vertical tracking force (VTF)."
Click to expand...

There's also an image of the moving micro cross:

1713999544368.png


And, this a cutaway of an MMC 3R:

1713999792506.png
 
profiguy

profiguy

Member
Joined 2007
Soundsmith is the authority on moving iron cartridges. They know most everything regarding the technology and refinement of MI. Grado did a bunch of MI carts as well. In general, MI is a little more top end peaking and emphasized. MI requires a bit more attention to loading capacitance and resistance.
 
M

mefistofelez

Member
Joined 2002
Greetings all,

thank you again for your education.

Given Galu's note that
Galu said:
the B&O cartridge does not have a user replaceable stylus.
Click to expand...
and profiguy's note that:
profiguy said:
MI is a little more top end peaking and emphasized. MI requires a bit more attention to loading capacitance and resistance.
Click to expand...
and the fact that this is all new to me, should I consider a different cartridge, for which a reliable, tested DIY design is available?

Kindest regards,

M
 
B

Boydk

Member
Joined 2010
Galu said:
I'll just add that the MMC 20CL was top of the MMC range
Click to expand...
With a little modification ;)
It was top of the 20 series-range. From low to high: MMC20S, MMC20E, MMC20EN & MMC20CL.
But this was one of the 2 types of connectors (the older one). After 20-series came MMC4000, MMC5000 & MMC6000. The 6000 featuring
a Pramanik needle, named after the inventor of the stylus shape. This was B&O´s Shibata.
The second (and newer) connector type for the newer arms featured MMC1-2-3-4 & 5, where MMC1 was the best and most expensive.
The 2 connector types were not interchangeable, and no adaptor exist to use an old cartridge on newer arms and vice versa.
mefistofelez said:
should I consider a different cartridge, for which a reliable, tested DIY design is available
Click to expand...
If you have a B&O turntable, I would think, that you´re in for an impossible task.
"Reliable, tested DIY design" for installing a standard cartridge on any kind of B&O arm doesn´t exist.
If you have a turntable with a standard SME connector for headshells, I think maybe the Audio Technica AT-VM series might
just be something for you. Easily upgradeable with better needle(s), if that´s what you want in the future;)
 
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profiguy

profiguy

Member
Joined 2007
Id look at the AT VM95ML MM cart. Its a bargain for how it sounds. The microline stylus profile is IMO the most accurate sounding, refined top end. The shibata profile comes in 2nd place, but almost as good, even though it sometimes costs more than microline. These stylus profiles are much more sensitive to cartridge setup than your basic elliptical stylus. The reward is far better treble accuracy.

Another good cart for the money is the Ortofon OM20 with the optional Fritz Geiger stylus. The basic OM20 is still a very good cartridge.

The older AT 150MLX is an outstanding MM cartridge, but its hard to find now that its discontinued. You can still get the 150SA with the shibata stylus, but it doesn't have the boron cantilever. Still an excellent cart. Its a lower compliance type which works better with lower mass arms, tracking around 1.5 g. Most of the newer cartridges track at 2 g and require a higher mass arm. Both the AT150 and AT540 are excellent platforms, even with lesser stylus profiles. The stylus type itself makes the biggest difference in sound IMO. Once you've listened to a good microline or shibata stylus, you won't go back to elliptical.

https://www.audio-technica.com/en-gb/cartridges/best-for/step-up/at-vm95ml

https://www.audio-technica.com/en-us/vm540ml
 
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