Moving Iron, or Moving Magnet...how to tell? [Archive] - Audio & Video Forums

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daveobieone
04-08-2009, 11:25 AM
Does anyone know a quick way to tell if a cartridge / stylus is moving iron, or moving magnet?

I was wondering if a compass would deflect from being near a moving magnet stylus?

Anyone have thoughts about the sound of the two? I know Stanton made both, but I'm not sure about other brands.

Is a moving iron cartridge actually closely related to the old variable reluctance (VR) type of cartridges?

Any phono cartridge engineers out there?

Dave O.

JohnMichael
04-08-2009, 02:17 PM
Dave glad you asked. A moving magnet cartridge has a magnet attached to the canitilever at the opposite end from the stylus. Audio Technica uses two magnets at a 45 degree angle from one another and the Shure cartridges had a single magnet at the end of the canitlever. The magnets moving by the fixed coil generates the output.

A moving iron or induced magnet cartridge has no magnet attached but the cantilever is in close proximitry to a fixed magnet. The cantilever generates a signal due to the induced magnetism from the fixed magnet of the cantilever as it moves near the fixed coils. The Ortofon OM and 2M, Grado, B&O, ADC XLM Mk 3 and others are induced magnet cartridges.

Of course there are also moving coils where a tiny coil at the end of the cantilever moves within a fixed magnetic field. The signal generated in the moving coild is smaller than the output of a moving magnet or moving iron.

The Stanton is a moving magnet but I have not heard one in too long a time and that was before I had the skills to optomize the cartridge in a tonearm. My tastes are for the induced magnet cartridge. I like my Ortofon OM20 and I remeber fondly the ADC XLM Mk 3. There are many good examples of all three types. The way the signal is generated may not be as important as the compatability with your tonearm.

emaidel
04-09-2009, 04:06 AM
That's a very good explanation of the different designs, JM. I wanted to add an interesting aside regarding AT's "Dual Magnet" design.

During the 70', when AT wanted to import Japanese-made phono cartridges into the U.S., they faced an enormous obstacle: Pickering, Stanton and Shure held a large array of patents on the single magnet design, and as such, none could be imported into the country.

AT, in a move of marketing brilliance, took a clever approach with the "two magnets are better than one," simply to avoid the patent obstacles. There was never any real benefit in the dual magnet design (the largest claimed benefit was increased channel separation, but Pickering and Stanton specs were far superior to those from AT at the time), and in fact, it actually increased effective tip mass, but AT set the standard in the industry for marketing brilliance. They took their biggest obstacle, and turned it into their sales story. Brilliant. Just brilliant.

hydroman
04-10-2009, 11:04 AM
Uhm if the OP er is asking 'which setting MC or MM on the input?'

You can safely cycle the switch (turn the volume to zero first, eh? ;) ) and the best sounding one is the answer.

JohnMichael
04-10-2009, 02:18 PM
Uhm if the OP er is asking 'which setting MC or MM on the input?'

You can safely cycle the switch (turn the volume to zero first, eh? ;) ) and the best sounding one is the answer.




I do not think he was. The outputs of a moving magnet and moving iron would both be in the high output range and he would need the MM setting.

Reticuli
04-10-2009, 04:20 PM
Is it safe to say MI and MC designs tend to have better (faster and lower distortion) high frequency transients, assuming the same thickness/material cantilever & diamond profile?

daveobieone
04-12-2009, 04:56 PM
Thanks John for the clear explanation of the difference between MM and MI!

I'm very clear on the difference with MC designs. I have a nice Denon MC, and the Denon step-up transformer. I've also used it with an active MC input pre-amp. The Denon 301 MC sounds nice on records that are otherwise fairly dull sounding...and it tracks VERY well. On records that are average, or bright, the Denon is just too bright for my ears...either with the transformer, or the active MC pre-amp. I prefer the mellower sound of my MM/MI cartridges...especially my Stantons.

I thought Stanton made both, moving iron, and moving magnet cartridges.?. I was under the impression that the 681 series (and most others below it) were MM, and the 881 was a moving iron.

Perhaps emaidel can clear this up for me? I have some 680, 681, and an 881s. I've not tried to substitute (swap) the styli from them. I know the 680/681 MM doesn't sound anything like the Denon MC. The Denon is kinda harsh...the Stantons are much smoother. Some might prefer the brighter sound of the MC Denon, but with my systems, it's just too bright on most records.

I'm still trying to get a handle on how a moving iron is different (or not) from a variable reluctance (VR) design. The old GE VRII was a variable reluctance design, and it had a moving metal of some sort, it a very strong magnetic field...which sounds (to me at least) a lot like a moving iron design.

Thanks again to all for the informative feedback...what a great group this is!

Dave O.

daveobieone
04-13-2009, 06:42 PM
I did a little exparament last night....

I plugged a Stanton 681eee stylus into a Stanton 500 cartridge body. It will fit...sort-of.

No sound.

I guess the 681 is a moving iron, and there's no magnet in the 500 to make it play.

Interesting...I've never tried this before.

Dave O.

emaidel
04-14-2009, 05:53 AM
The Stanton 500 (and the corresponding Pickering V/15 models) were all moving magnet. The 680 and 681 Stantons (and the PIckering XV/15 models) were moving iron. The 881-S ( and PIckering XSV-3000) were moving magnet designs, but used Samarium cobalt magnets which, due to their powerful nature allowed miniscule magnets to be used to greatly reduce tip mass as compared to the much older 500 design.

I think it's fair to say that moving iron or moving magnet designs can each be of very high quality: it is the nature of the overall design that matters the most. the ADC XLM models (all induced magnet/moving iron) were outstanding models in their day, but extremely delicate and easily destroyed by not properly handling one's tonearm. In my opinion, they outperformed the Stanton and Pickering moving iron designs, but the later Pickering and Stanton moving magnet designs, starting with the PIckering XSV-3000, outperformed the ADC's, and were able to withstand a good deal of abuse too, without any damage to the stylus assembly. Still, it's very much a matter of personal preference.

.

Reticuli
04-14-2009, 05:40 PM
Is the 890 series the same as the 881 body? Are there any nice quality elliptical tips out there for them in the compliance range of 20-13 (in whatever units stanton is using) ?

For how old the 500 body is, I think the sound of the elliptical tips from the last 7 years have been amazing. Didn't some designer for Stanton/Pickering say the E mk2 used rare earth magnets to radically update the design?

daveobieone
04-16-2009, 12:48 PM
Just as an update to my earlier post...

I did try my 881s stylus (MM) in the 500 body today, and got sound. The level was pretty low, but it did make sound. This is counter to the 681 (MI) in the same body, which wouldn't make a sound.

I'm guessing the pick-up coils in the 881 cartridge body are a lot more sensitive than those in the old (inexpensive) 500.

So, I guess I've sorta learned what I wanted to know, and developed a method...at least with Stanton / Pickering.

I've also been amazed with the sound of the newer Stanton D71ee Hi-Fi stylus in the old 500 series bodies. Takes up to about 2 grams to really clean-up the tracking, but that combination really sounds quite good to me. And they are cheap. KAB has them (genuine Stanton) for $20! At 2 grams, there still doesn't seem to be any significant record wear, even on styrene 45's.

Dave O.

Reticuli
04-16-2009, 07:09 PM
I don't know. I would think the 500 tips might be more powerful, but they're all the cobalt magnets on the short inner end of the cantilever that goes into the MM assembly, right? Is the compliance in the 14-16 range? Because if it's more like 20 or 30 units, it will put out a lot less.

Oh wait, the 880/890 is higher inductance, so it is probably more windings and therefore higher output. Weaker magnets need more coil windings to get the same output, and thus cause higher inductance. Similar magnets with more inductance means more coils for higher output. So yeah, you must be right.

Aren't the D71ee tips very close to bottoming out at 2 grams? Even the slightly stiffer single e is real close to bottoming at 2 grams, but is very clean at 1.75 grams. I would think the slightly more compliant ones you have with the better diamond would be pristine at 1.75. It is the .3 x .7 diamond on the little box insert, right? I might have to get a pair to try now.

Are either of yours loose at all? Did they require the putty? And the weird top of the housing doesn't come up against any obstacles or lack alignment assurance? The 72 body has that top part that it sits against to get it strait on. Strange that Stanton went with a narrow stylus housing rather than that wide technique that goes around the front sides snuggly.

daveobieone
04-17-2009, 06:45 PM
Mine fit tight enough that I'm not worried about them falling out, or rattling around. I need to get some of that "blue tack" stuff, and give it a try. I've heard there's a less expensive product from Elmers that's similar. You can rotate it (twist it more from side to side) than with a "real" 500 series stylus...but as long as it's pushed in all the way, it seems to self-align fairly well. The rest is simply lining it up by eye. It was kind of a silly move to make the grip so small. The 700 cartridge body is (I think) just a P mount version of the 500. The top of the stylus grip fits and lines up fine over the top of the cartridge body.

Mine don't look like they are ready to bottom-out at 2 grams, and they do sound quite good even at 1.6g. I only really have one record, with one spot with a super intense "S" sound that causes it to break-up a little at less than 2g. It's my ultimate tracking test.

I may be all wet on this, but I'd think that miss-tracking distortion can cause more groove damage than tracking a little heavier. I'd love to hear some feedback on that from the more knowledgeable here.?. If you are back-cuing all time (as we always were in radio), lighter tracking might be a more appealing way to go however, to avoid cue-burn.

We always tracked the 500a (NOT the AL!...which I hated) at 2.2 grams. At that VTF, even the styrene 45s held up very well to all the back cuing. Of course, the 500a was a .7 conical. I have a ton of 45s that were cued a thousand times or more, and you can hardly tell. THANK YOU STANTON!!! We could NEVER get away with that with any Shure.

I also noticed the nearly double inductance of the upscale models. That actually might have something to do with why I seem to like the sound of the 500 body so much...or perhaps, it's just that the sound is so familiar to me. My records just sound "right" with the Stanton 500 cartridges...probably because I've listened to them on those since the early 70's...for many hours on the air every day.

I don't have anything with enough magnification to really see what the stylus and cantelever looks like up close.

daveobieone
04-17-2009, 07:03 PM
BTW, I used to change those 500a styli at about 3 months on the 24/7 radio stations. That would equal about 1000 hours of running time.

Seems like I could hear some loss of quality beyond that.

Of couse, sometimes they got changed before that...of the jock dropped the stylus on the felt while spinning the table backwards. No stylus could survive that! I always used to keep a used stylus in the Staton cube in the studio, next to the turntables...so the clumsy jocks could do a quick swap.

Dave O.

Reticuli
04-18-2009, 12:43 PM
I have some high grade digital recordings and vinyl cuts of them, and on a great many of them the 500 is pretty much the only cartridge that seems to mimic the original digital sound faithfully in "tone". The high compliance ellipticals are a little too recessed in the mids and hyped in the highs, and the ALII is lacking in micro-tracking ability, transient speed, and extreme extension on top & bottom. But it seems like something in between the two tips would probably be a sweet spot. I would put the Audio Technicas in second place in this regard, though they seem to be lower distortion carts.