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

I also have no doubt, based on everything I have read about Peter Lederman and what I have seen him say himself, that if you sent a cart in at 500 hours for inspection and it was indeed worn to the point of needing retip, he’d confirm that. I really don’t get the impression that man is trying to screw anybody or misrepresent anything.

 

Unfortunately I see record wear as something very difficult to know generally. So many variables.

 

I agree. It's difficult to get a good look at a stylus to see how worn it is, but much more difficult to view a record groove in such detail, and once you do view it you have no good quantitative way to measure it in order to say whether it is new/worn/damaged. If the record is a test record with fixed tones, I suppose you could measure frequency response and distortion and such, but for a music record with constantly-varying content it would seem to be very difficult to measure the effects of damage. Plus there are the variables of the playback stylus itself which could have impact on the measurement. Some cartridges/styli have been marketed specifically stating that their shape and depth in the grooves can avoid the damage caused by lesser styli.

I seem to remember a turntable which played records with reflected lasers. I supposed made a recording with a new record, then after some number of plays (with diamond stylus) recorded it again and compared, you might glean some info. But is the laser giving anything like a definitive look at the grooves? Does it also have the same variability of where on the groove it is scanning? I don't know much about the way these laser turntables work.

There are of course surface metrology tools today such as AFMs which can tell you the shape of the surface in detail. Even the photographic techiques I use for my work can give an excellent representation of surface topography for non-retrograde surfaces, but they rely on getting good lighting onto the subject, and on the reflective properties of the surface. In the few attempts I have made to image a record surface, it became clear to me that lighting is gong to be very difficult, and will require a lot more effort to get a diffuse enough illumination of the groove surfaces to properly render a perspective/3D view. I am still trying to do this, as I don't see a better, non-destructive way to do it.

 

One possible way to do this, I don't know for sure, is to employ IRENE, the device developed by Lawrence Berkeley Labs. It's not exactly something one would have in their home-- I know the Packard Campus of the Library of Congress has one, and there is one at the Northeast Document Conservation Center. It uses cameras to detect the information in the grooves, scans and records them. There is a visual record and the audio is extrapolated into a digital audio waveform. See generally, Understanding IRENE
But, even if one went to that trouble, I would expect that a different stylus shape might make damage in one part of the groove less apparent. Sitting in one of the suites at the Packard Campus listening to these old Les Paul acetates that they were digitizing (the actual acetates would get stored in a vault; the digital copies were what people generally accessed thereafter), the preservation specialist had a whole variety of styli that he could plug in, depending on the disc. (I have a photo of that stored on an external drive, along with some others from my visit which didn't make it into the published article).
I suspect it would be pretty costly to get one of these places to do such a project--
using the same record- starting from new, clean it and image it. Then play it using a worn stylus and image it again. Easy enough to ask if that would work. Cost and availability of such a device would be a whole other question, though it would be an interesting study if feasible using IRENE.
At the end of the day, even with all that, there are lots of variables, as several of you have noted. And I'll also wager that as much has to do with proper set up in the first place, as well as cleaning, tracking weight, etc. (ground we already covered here).

 

IRENE looks pretty cool, though it looks like it can only do mono recordings. They talk about doing vertical demodulation for cylinders, and lateral demod for discs, but not for combo of vertical and lateral as would be required for stereo.

I will keep trying on the lighting, and if I can get a good image I'll report back.

 

Getting an image of groove wear should be doable...I've seen many online and in print from decades ago. I don't imagine it's very easy.

 

All the ones I've seen are SEMS, which are destructive. I'm hoping for something I can do to check on records that are still playable after. Have you seen any optical images showing wear, and if so, please give some links.

 

Here's one to start with:
Micrographia: Applications: The microscopy of vinyl records. Page 2.

 

Thanks for that! That level of quality is not so tough, and given the damage can be easily seen is very encouraging. Tough to quantify though.

 

That one image of wear is "only" at 200x. That's in the range of digital microscopes that are commonly available. I found them pretty difficult to use, but it's certainly within the reach of somebody competent. I thought you needed something on the order of a scanning microscope to really see what's what.

 

Some more pictures, cell phone pics from the book, Handbook For Sound Engineers, 3rd printing, 1988:

Oops... where's the upload dialogue?

 

Even though it says "200x", that image was done at much lower magnification. USB microscope specs include the "digital magnification" from sensor to screen, typically 30x (from a 2/3" sensor to 23" monitor). Optical microscopes magnify the image by the eyepiece mag, typically 10x. It's hard to tell what actual mag the objective had, but I'd estimate it at 20x.

Here is an example image I took of a record surface, using a ringlight at ~50deg vs horizontal, focused on the bottom of the groove in order to show the radius of the groove bottom. This image was taken at 10x magnification. The note on the micrographia image says that they used vertical illumination. I plan to try that to see if I can get a similar look to the image. In this case I was not looking for groove wear, only for a good idea of the bottom radius:

 

The impact from an 8g VTF contra a common VTF used today is of course enormously more.

 

i change my stylus every 10 years, whether it needs it or not

 

It is still a topic of interest, especially when buying box lots of used records. I've heard examples so severe it would've been interesting to actually see the damage. What caused it might then have become better understood, recognized and possibly avoided.

 

It is absolutely interesting, I´m not saying it isn´t. You will always learn something. I´m just saying the groove wall forces are very different.

 

Wear at lower VTF would be harder to identify, but I assume it would present similar patterns of wear for similar stylus shapes.

 

Possibly, it can also be so that similar records won´t show any wear at all.

 

Is the reference to 8g tracking force something pertaining to the link @Ripblade posted, or to the Weiler study discussed in Mike's article?
No doubt tracking force, along with stylus shape play a role (along with set up, record cleaning and some of the other factors we discussed). Although there have not, to my knowledge, been recent studies of any depth, Mike did find evidence of stylus wear in the more modern cartridges based on his own experience and examination of his cartridge by Expert in the UK as well as information from manufacturers, including Ortofon, as well as anecdotal reports by other users who had similar experience in shorter than claimed life. One point worth underscoring is that Mike advocates the need for a controlled study utilizing current playback equipment.
How that translates into record damage is a different question and one which is equally deserving of a controlled study in spite of the variables all of us acknowledge.
I made a few phone calls today about just such a study. Whether it is feasible or worth the expense of underwriting is something I will be exploring.
PS: another variable that may have gotten lost in the discussion is vinyl compounds.

 

I think that would be unlikely. Maybe not audibly within normal human perception, but certainly, at some point the vinyl deformation becomes permanent.

 

It´s reasonable that record wear is about groove wall forces. It´s not necessarily so that with a low VTF high enough groove wall forces are obtained.

What I mean is that the highest groove wall forces are obtained when accelation is at max, but if the tip mass is low and the needle damping is low; the difference with a very low compliant needle with very high damping is enormous.

 

Logically, if the VTF is in normal range such that the stylus is not mistracking, then if there is sufficient force/friction to wear a diamond, wouldn't we expect groove wear?

There have been discussions regarding dust causing "cratering" of the groove. I guess the explanation is that the dust caused a localized high pressure on the vinyl surface, breaking away some vinyl. This supposedly leaves a permanent tick or pop at that location. This is something I hope to look for.

Folks also talk about other causes of visible damage, such as mistracking, excessive VTF, and HF attenuation due to worn styli. I expect each of these phemonena would cause a different visible damage signature.

 

In the mid 1970s when I was in grad school I had one particularly noisy record in Sly & the Family Stones’ Stand. It was an assault of groove wear, clicks and pops, so bad I replaced it. A school mate worked in a lab with a scanning electron microscope (SEM). He agreed to image a bit of the lp. So I broke it up (harder than you’d think) to secure a 1”x1” fragment. He electroplated that bit in gold to get the image.

I was stunned when he showed me the high resolution images in black & white. The grooves looked pristine to these untrained eyes. I saw no pits or debris in the record grooves, just smooth undulating v-shaped canyons of vinyl.

This topic is fascinating, I’d like to know more. Thanks Ray for your diligence.

 

My guess is that there will be a small difference at groove wall surface if the record has been played or not.

 

Weiler's 1954 study used 7g vtf on a 1 mil. conical stylus, playing on records of the era of questionable cleanliness compared to today's methods of record cleaning.