Coils & Magnets

[RobbieGong]

How much of an issue or compromise are the magnets in a mm cartridge ? The reason I ask is that common consensus is that when it really comes to it a mc is 'better'. I've read things such as mc's generally being more nimble, fast, transparent, airy etc as a result of not having the 'heavy' magnets that a mm has. I've never had a mc (hope to try one someday) but the 2M Black I have is highly regarded as a mm because it protrays mc like characteristics. How do manufacturers work around the 'heavier' magnet issue with mm's and pull close to that mc sound ?

[Firebottle]

A damn fine question Rob, one I would be interested to hear the answer to myself.

:cool: Alan

[Macca]

well according to wikipedia

MC cartridges offer very low inductance and impedance, which means that the effects of capacitance (in the cable that goes from the cartridge to the preamp) are negligible, unlike MM cartridges, which comparatively sport very high inductance and impedance. In the latter, cable capacitance can negatively affect the flatness of frequency response and linearity of phase response. This would account for a sonic advantage to MC types.

But:

It is generally believed that MC cartridges sport lower moving masses. However, quality MM cartridges are able to offer as low or lower moving mass than some MC cartridges..
To discriminate cartridges by engine (MC vs MM) overlooks the fact that the stylus tip shape and cantilever have a significant influence in the sound, and this may account for more variation of sound quality than the engine type used.

Personally speaking I've never found there to be much in it between a good MM and a good MC other than the good MC was more expensive, but I'd guess I'm in the minority there.

[struth]

A conventional magnetic cartridge normally uses a solid magnet, either permanent or induced moving close to a set of coils. In Ortofon’s patented Variable Magnetic Shunt (VMS) design, the stylus cantilever is attached to a very light tubular armature which moves between the coils in the field of a miniature ring magnet.
VMS diagramThe Ortofon VMS armature is a tiny, thin-walled tube placed at the end of the cantilever. When the stylus moved, the movements of the armature cut the flux lines of the magnet. By so doing, it functions as a magnetic shunt.
VMS advantages include low moving mass, high channel separation, low distortion, minimal record wear and a superb three-dimensional sound which brings concert hall realism into your home.
Please see the diagrams showing the VMS principle (for simplification only one channel is shown).
The symmetrical flux fields with the armature in the central (neutral) position. These fields emanate from the magnet positioned in front of the pole pins. As the fields are in balance, no changes in flux occur around and inside the coils: therefore no voltage is generated.
What happens when the cantilever moves the armature closer to the magnet. In this position the armature acts as a shunt, short-circuiting part of the field. As a result, the field in front of the pole pins varies, and the voltage is generated. This also occurs when the armature moves in other directions.:eyebrows:

[YNWaN]

The better sounding (in my experience and that of many others) MC cartridges have very low output - because they have very few turns of wire in their moving coils.

[paskinn]

A subject close to my heart; I have mainly used MCs over several decades, but never really 'settled' or been convinced by the technical claims. For me, a good moving magnet can offer an equal, or possibly better, performance. The confusion perhaps comes from the extra investment made in mc cartridges. If the market demands that the best styli and cantilevers 'deserve' mc technology, then that is what you get.
To my ears the trade-offs, put very broadly, are that MCs often seem more detailed and even 'etched', with a greater sense of space and precision. The better MMs often seem more natural to me, with a greater sense of body and tonality but less obvious 'high fi' traits.
My last MC was a new Koetsu Urushi, my current cartridge a Grado moving-iron unit, with low (0.5mv) output.Very low windings. So, both mc and mm traits in some ways. I generally prefer the Grado, although that is always a personal judgement. It cost about 20% as much. Money is an unreliable indicator of quality above a certain point. Personal taste is a greater factor.
One of my favourites is the dear old Shure 97xe. £70 and very natural sounding for the price.
There is thus no 'correct' answer to the question. I doubt that, given equal development, any of the technologies has an over-whelming advantage. To my ears, many MCs are simply too bright, a touch unnatural, all in the name of 'detail.' But even good MMs and moving-iron may lack the 'hyper-detail' some people crave. So, for me, this question cannot be answered just by reference to technology.
It's you..the listener...that is the critical variable.

[YNWaN]

I wouldn't say 0.5 mV is that low - 0.2 or lower is low.

A lot of MC's are voiced to have a HF lift - particularly since the introduction of CD; but not all. A good MC has a level of tonal range/subtlety that a MM seems to paint with a broader, and rather coarser, brush.

[RobbieGong]

Excellent and insightful responses ! It's why I'm glad I'm here :)

[Oldpinkman]

It's something I've always wondered - and never really understood. I was a long time fan of the Technics U205C Mk3 - and that saw off all-comers at PT for at least 5 years, as the only cartridge any of us used in our own systems and the only cartridge used at shows. It still takes a lot of beating - although they are a dying breed - the one I picked up had a perished suspension, and the Jico stylus both seems to add a bit of "sheen" that was maybe missing, and lose a bit of the "ethereal". (I'm no fan of describing sounds - to borrow from Sovereigns description of my ESL63's as "speakerless speakers" ethereal should be read as "cartridgeless cartridge".

And I was a shocking inverted snob about moving coils - especially the Linns and Koetsu's (both of which Arthur assures me are better in their modern versions). I think it is fair to say that a lot of cheaper moving coil cartridges are chosen because they are moving coil and that is "better", when actually they are fairly horrible. I can think of one such device regularly praised on this forum, which I got to hear properly last year, and it was the old bad MC experience for me again. But, I was astonished by the Dynavector I now have - which is in another league to anything I have had a proper chance to listen to before. This just does nothing wrong and everything right. It is probably a really good synergy with my TT and arm, but even so its a stonking good cartridge. It was so good, that when I plugged it in for a first listen, Sue had said "you'll have to buy it" within 15 minutes, and before asking how much it cost.

But I think a good MM beats a so-so MC any day. And a good MC needs a good phono stage to really shine - and a low noise one at that.

Of course, there's always Decca's

Or variable capacitance transducers... :eek:

[zombilly]

I use the VMS30 MKII in a SME 3009 on a Thorens TD160 mkII modded and prefer it to the mcs I have tried-ATOC9,Dynavector Karat and DL 103. Addmittedly on a different deck,the Audioclear Emotion modded so not a direct comparison either way I cant see me going back to mcs.