The Finish Line for your Phono Cartridge- Stylus Wear by Mike Bodell

Sort of, depending on what you mean by "kept its shape". Like other stylus types, the MR has both a minor and major radius when new. Also like other stylus types, wear causes a flat to form, so both minor and major radius flatten-out. From this perspective the shape is not kept. However, even when the minor radius has worn flat, the contact width increase is limited to the width of the ridge, and stays at that width until the tip wears to the base of the cuts that form the ridge. So while the shape is not really maintained, the contact width doesn't increase as the tip wears, unlike other stylus types.

 

Exactly, the flats only become as wide as the ridge diamond material extends, which is not very much. At least until the entire ridge is gone.

 

I agree that they radius increase gradually as wear goes onto look as flat but never completely so looking at the surface of it. Looking at the MR above, it has sharp flats all along the ridge, I would not expect that. Even your heavily worn elliptical example above does not show sharp corners.

 

Ledermann talks about these styli cuts at the end of this video:

 

Or perhpaps the sharp corners are due the image. The front image in a post later shows shadowing around the perimeter/contact points that would indicate that the stylus still has rounding.

 

I would think that wear that eaten up the ridge would be a "very" old stylus. But perhaps the EM images are fooling us a bit. It is not entirely evident that there is a complete flat. It could just be polished down. It could well be that a new stylus could look similar in the EM; shadowing can fool us.

 

The laser cuts which form the ridge are made at 45-deg angles, so for maximum lifetime the MR types need to be aligned with minimal skew.

A little earlier in this thread I wrote that "ML/MR/SAS styli have a reasonable range of tolerance of azimuth error", but looking at the drawing of the 150MLX, and the profile SEM, it seems that some types have a nearly-45deg contact area when new. This means those types need to be nearly perfect in alignment or they will contact at the top of the groove rather than the bottom. Looking at the drawings it appears there are just 2 degrees or so of error permissible. See image below:


Image modified from AT drawings showing the 150ML stylus type.

 

I think that if I do another stylus wear study I'll need to run an MR stylus of some sort. There seem to be quite a few unanswered questions and outright mysticism surrounding this stylus type.

 

That would be very interesting if you could do that. Either it is so that the ridge is worn down much quicker than any other stylus (because of "less material" to tear down). Or it has a longer life because the ridge itself maintains its shape and thus contact patch until stylus bottoms out.

 

Peter Lederman knows of what he speaks.
He was the first guy to tell me the difference between tracking (which is what most look for in a cartridge) and tracing.

The fine line stylus, with diamond cantilever - a Bang & Olufson - was a revelation.
Sparkle, detail and even on Depeche Mode's Black Celebration (early US pressing) there was a remarkable shimmering detail.
Those electronics were not just bing bang boing. They were now organic sounding.

Anyway, one night I left the house, unwittingly and stupidly, with the turntable playing the runout groove over and over for a weekend.
Shortly after that, I noticed that records played sounded good, but on a second play, had a slight less sparkle.

Peter examined the cartridge and was surprised. Yes, he said, the stylus was now "shaving off" stuff in the groove.

This was after using the cartridge for well over 500 hours.
I'm guilty for abusing it.
Had I not, it would probably be still in play today.
A moving iron, fine-line microridge stylus, by B&O is a fantastic, and giant killer of a cart.

 

I went directly to 800 hours, stopping at 700 only to clean the record and stylus but did not take pics.

Here are the 800 hour pics. I see only a small amount more growth in the width of the contacts, but I do see a visible flattening of the profile view. It looks like there is now an actual flat forming, though it is still fairly subtle. Here are the two contact views, and an animation of the very tip of the profile view between T-zero and 800 hour checkpoints:

Left


Right


Profile T0 vs T800

 

Incredibly good work, a true reference!

 

Can I ask on what deck you used the mmc2 cart (I also have one,but it is presumably let down by the b&o deck) ?

 

Thanks Thomas!

I added groove detail to the Profile view, and found that the wear patches are skewed by 2.5-deg from horizontal. I've always imaged the stylus as if it were perfectly-aligned, but indeed it has a slight misalignment that is now showing up as the wear flats are forming:

Edited to add: The distance between contacts at the bottom of the groove is ~0.5 mil, still well above the ~0.25 minimum to avoid groove bottoming, so this stylus has a lot of wear left by that criteria.

 

Many would have sent the cartridge in for an inspection and possible re-tip by this time, based on hourly usage alone.

 

The Bang & Olufson RX.
I got lucky, according to Peter Lederman at Soundsmith, who was going to service the deck.
The speed was spot on, still, after 15 years.
And he told me that the B&O's leaf springs are far better, and more easily adjustable than spring suspended tables in use even to this day. No mussing and fussing with leveling suspension, ever.
When I told him that I'd thrown the cartridge adapter away (for any other non-p-mount turntables) he almost turned white with disappointment!
I tell you, the reason Peter still uses Bang & Olufson parts for his stellar cartridges is because they are underrated.
As are the original B&O higher end carts. He told me that, when asking about comparisons to other carts, the MMC2 is very underrated, and is better at tracing - not just tracking, than most carts costing much more.

The downside is that the RX turntable doesn't have the the best platter, as they can easily warp, which will subtract some bass and midrange.
The lightweight tonearm and cart wont put damage to your records as long as you keep the tracking force at 1.75. But that light weight means it wont track demo discs with canons. Such as the Telarc 1812. So what. It tracks, and traces with aplomb everything else. It doesn't give you the "this is vinyl" experience of other tables. But it does give detail more than the cd.

It doesn't compare to the slightly more expensive vintage turntables such as the Denon direct drive from the same 1980's or the Kenwood "polymer" turntables. The arm/cart combination absolutely hates later DG pressings (the early ones are great.) But it loves early London/Decca classical, (especially in mono), vocals, rock, and, oddly, flutes! You can jump, dance and it wont flinch. You can scrape the cartridge across the record and it wont leave a single mark.
The RX with a new MMC4 will be great for rock. With a new MMC2, you're going to pay 1K for the cart alone - five times the price of the table. But get savvy and you've got a tracer that will outperform other cartridges costing much, much more.

Get really lucky and score a NM MMC2 and adapter for other tables and you've got yourself something that will blow away carts costing much more. The tracing is incredible.
Anyone looking for a pre-owned budget table for under $200.00 will do very well with a B&O RX or, better RX2 - but use a ruler to make sure the platter is flat.

B&O has been unfairly snubbed here, perhaps because of their "proprietary" everything. And the fact that they've put "design" over performance. But this Danish table served me well for many years - using it every single friggin day. Why it isn't recommended for someone seeking an entry level table puzzels me.

 

I would have based on my experience. Then again, my employed VTF is double what Ray is using. We know VTF is a critical variable too. And of course my turntable is a uni-pivot suspension and radial arm, not a linear tracker. My 800 hours would be accumulated on thousands of records of varying quality.

 

I agree. I used B&O turntables for 25 years beginning in the mid-1980. I had a 1600, 1800, and finally a TX2, and I owed several of those. The MMC-2 cartridge was my go to, while I also used the MMC-3 and MMC-4. At the same time I owned a Technics SL-1300.

 

Agreed. I believe uncleaned dirt and debris left in the groove, along with physically damaged records (microscopic rips and tears in the groove wall that produce the common "ticks and pops" of varying loudness heard on playback -- each one like a miniature spike that the stylus strikes, the accumulation of which acts as an abrasive force) are the main causes of stylus wear. Of course the higher the VTF, the more the abrasive force on the stylus.

 

Thanks (and sorry to OP as this is getting a bit off topic), you convinced me to give my bg9500 (and bg3000) with mmc2 another spin. Last time I checked though, they were lacking in bass and soundstage, but had indeed great detail.

 

Very interesting

 

The study was on-hold for a while, but the record is spinning again on the way to 1000 hours. I will likely terminate the study at that point, but I do want to see how the stylus looks at 1000 hours since that's a typical lifetime milestone quoted by some mfrs. I'll clean the record and stylus at 900 hours as I did at 700 hours.

 

Are you playing the same record for all the hours as well?

 

Yes, of course. I would not make a change to the experiment in the middle.

 

Nice, that was something I was going to study sometime as well. Did you record the first or so play to compare with ones later on? It would be cool to know how the grooves are holding up on the stylus youre using after this many plays.