#moving coils

Rabbit hole time!

I have too many. I have 4 mounted and ready to run. I have three more in boxes or laying on a shelf. This started as my boss cartridge was old and replacement styli were getting scarce and twearnt that good. I needed something more up to date.

Unlike many things Old phono cartridges are not necessarily any good. Styli wear out and suspension polymers age and harden. Even NOS are suspect. You really need new stuff here.

The journey started rationally.

There are several types of cartridges or pickups if you prefer. The magnetic team have three types. There is moving magnet, then moving iron, then moving coil. All use coils of wire within magnetic fields to generate tiny voltages that are amplified in a phono stage preamplifier.

There are other types too. There are exotic strain gauge types that use cool solid state technology to read movement of the stylus. Those require exotic circuits and support devices and do not need a conventional phono stage. There are capacitor based pickups that work like microphones do and also need special electronics. There was (is?) a laser beam based type that was way off the technological deep end. All are rare and expensive.

Finally there are crystal types that use piezoelectric crystals to generate voltages directly. All of those are cheap crap and need only go in the bin as soon as they are encountered.

The meat and potatoes of these things are the magnetics. Prices range from less than 50 bucks to over 300 times that. My most expensive unit is about $500 to $700 dollar replacement cost. The cheapest (on the shelf collecting dust) was $50 bucks.

Moving Magnets are abbreviated MM like the candy. In those tiny magnets are bonded to the stylus and wiggle around near coils of wire that are fixed in place. Those are really common and range from OK to OMG! Audio Technica (AT) makes really good ones. They are vulnerable to capacitive loads as the coils need be fairly high inductance and can react badly to too much capacitance in the preamp and the wires leading from the pickup to the preamp. Most of my pickups are MM.

My preamp has about 50pf load on its input and likes Audio Technicas fine. Some preamps have almost 600 pf and that makes some MMs sound awful. It may not be the pickup but the preamp if you have troubles.

Moving Iron (MI) are really interesting. In these there are coils and magnets both are fixed in place. They exploit a thing where moving a piece of iron (magnets really like iron) near the end of a pole piece will make a current in the coils. The magnets can be quite big which allows the other bits to be small. The piece of iron bonded to the stylus can be really really small. Grado and Soundsmith specialize in moving iron types. The least expensive of these is the Grado Black at around 100 bucks. The most expensive Soundsmith listed on their site is $8000 USD. The most expensive Grado is $16,000.

Grados advertise incredible bandwidth. Bass down to 10 hz and treble up to 60khz which is more than dogs can hear. I have a Grado Opus3 the cheapest of the top line. They claim they are immune to preamp capacitance problems.

Soundsmith also makes new Bang and Olufsen MMC (moving micro cross ) cartridges which are a particular type of MI. B&O cartridges are coveted by their fans.

The GURU of Soundsmith Peter Ledermann advocates with great fervor that moving Iron is the best and moving coils suck. Visit the website for the lecture.

https://www.sound-smith.com/articles/fixed-coil-vs-moving-coil-why-make-jump-different-technology

Very well thought out actually.

That brings us to moving coils (MC). It is accepted by many that anything but MC is dog shit. It is literally an article of faith. Let the golden ears guide you child. In MCs the coils are wound on tiny armatures and these are bonded to the stylus cantilever. It is finicky and the stiffness of the armature, size of the coils, and how they are bonded all make a difference as they wiggle about.

Most larger manufacturers make MCs as there is a demand. AT, Denon, Ortofon, and several others sell what people buy and are good at it. Ortofon is the largest selling producer of all types is over 100 years old and has about 100 employees. Big is a relative term.

I explored this as there are some affordable units of good reputation. But it is never that simple. MCs are usually low output and good ones require either special preamps or input transformers or other voodoo all not cheap. Adding that to the cost of the pickup makes them all fairly expensive to own. Another common thing is they are usually disposable. Once the diamond wears out you either buy new, or send it in to be retipped. Not cheap.

Retipping is also true of Soundsmith and the high end of Grados. Not having replaceable styli has subtle benefits to performance.

A large factor to MC popularity is that high end manufacturers expect customers to use MCs so they adjust (voice) their products to favor them. (Audio Research) You can adjust it back if comfortable with solder.

As faith is involved debate gets heated. Actually not debate which is a rational logical process. It is a bloody fight between sides.

As I value rational thought I scraped through the debris of battle and found some information. GRADO had an original Patent on MCs decades ago but decided it just was not as good for them. Doug Sax a recognized master of making LPs did not like any MC types. He QCd his master lacquers with moving magnets or moving iron. He really liked the Shure V15 mk 3 and up. Mr Ledermann is quite convincing as well.

Add to all that is it is plain that some types of distortion are enjoyed and preferred. Microphonic vacuum tubes can add an aire and texture to the sound that is not on the recording, but sounds so nice. Apparently MC pickups can do the same thing.

In any event you really have to spend big bucks to appreciate the differences or even to detect them.

I can testify to the overall sound of my collection of pickups is quite similar. The key middle parts with vocals and particular instruments are all pretty good. Differences I find are in tiny details and textures. Most telling to me is rendition of space around a performer. The lower end units sound flat, as in front to back. Better units sound deep.

My current Boss pickup is the Grado Opus3. I have nothing bad to say about it. It is similar to the AT 440 and 7V but with just a bit more something.

That all brings it down to cost. The Grado Opus 3 is about half the price of the "good" MM ATs. My Preamp would cost 3 to 5 times the cost of the cartridge to replace. I am convinced you need that level to appreciate this stuff. The Turntable is also from 1.5 to 5 times the cost of the cartridge.