I'm glad I didn't come across this thread while it was in full flow. 🙂
As it is, I've wasted a whole day going through it and following the links 😱
I've dabbled in cartridge design though, unlike my efforts on speakers, amps & mikes, never as successfully and never for commercial products.
My mentors where Tony Emerson and the polymath, Dr. Don Barlow who used to do it for LEAK.
If I may put my 3 x $0.02 in ...
___________________________
disk melting etc
IIRC, in the early 70s (?) John/Jean Walton who designed the Deram for Decca & had a hand in some of their MI cartridges published a small booklet on record wear .. including, I believe the earliest SEM pics of a groove.
He identified tip mass as the most important factor. His criteria of 0.5mg is met by most 'nude' stylii today but not all shanked stylii.
He also found that with less than 0.5mg, a spherical stylus could have less distortion than a more massive 'elliptical'.
He concluded that the improved sound of the better elliptical stylii was often due to the smaller lump of diamond & hence tip mass rather than tracing distortion.
The dynamics of the record groove are truly dynamic. 🙂
But the interesting thing with regard to this thread was that the SEM shows the groove is polished on 1st play by a low tip mass cartridge. Subsequent playings don't change this (TINY compared to the diamond) polished track much provided the tip mass remained low.
Above 1mg, the groove is irreparably & repeatedly damaged on each playing.
I leave yus pundits to explain the mechanism for this polishing and its relevance to clicks & pops 😀
If anyone has a copy of this booklet, it would be nice to have a copy on the WWW.
_____________________
Friction
Also in the early 70's, John Wright was working on the Audio & Design, mercury contact arm. He published an article in HFN on experiments with anti-skating.
He had a headshell which was pivoted so he could see if the anti-skating was correct.
What he found was that the anti-skating required varied with modulation and also the cartridge
Cartridges with small cantilever damping like the Decca needed less than those with more like the Ortofons.
'Skating' force is of course a direct measure of the 'frictional' forces at the tip .. at least along the line of the cartridge.
It may be Hans' MC cartridge has high midrange damping and hence would show little or no change in 'groove friction'.
I'm not sure how this tidbit helps the argument that 'groove friction' effects are a cause of ticks & pops but it might explain why he doesn't have any change in 'groove friction'.
Hans, can you tell us what is your cartridge?
___________________________
Lastly, in Jurassic times, I was a firm believer in wet playing.
The cartridge was usually a modified ADC XLM/VLM. This doesn't have an earthed cantilever (which the SHUREs do) and that is responsible for at least a few clicks from static when played dry.
I also had access to a KM record cleaning machine and used a Discwasher (IIRC) too.
___________________________
BTW, the mechanical response of a cartridge is complex. In most cartridges, there are at least 2 interacting resonant systems at HF close to each other.
One is the vinyl compliance against the tip mass.
The other is the cantilever compliance (what's usually quoted in specs) vs the tip mass again.
This leads to non-intuitive results like .. a stiffer compliance can often lead to better HF response, trackability, bla bla.
There's a number of SHURE papers in JAES which detail each new variant of V15 from Type II onwards which describe this.
Also a paper on the 'quad' M24 which details some of the tuning.
As it is, I've wasted a whole day going through it and following the links 😱
I've dabbled in cartridge design though, unlike my efforts on speakers, amps & mikes, never as successfully and never for commercial products.
My mentors where Tony Emerson and the polymath, Dr. Don Barlow who used to do it for LEAK.
If I may put my 3 x $0.02 in ...
___________________________
disk melting etc
IIRC, in the early 70s (?) John/Jean Walton who designed the Deram for Decca & had a hand in some of their MI cartridges published a small booklet on record wear .. including, I believe the earliest SEM pics of a groove.
He identified tip mass as the most important factor. His criteria of 0.5mg is met by most 'nude' stylii today but not all shanked stylii.
He also found that with less than 0.5mg, a spherical stylus could have less distortion than a more massive 'elliptical'.
He concluded that the improved sound of the better elliptical stylii was often due to the smaller lump of diamond & hence tip mass rather than tracing distortion.
The dynamics of the record groove are truly dynamic. 🙂
But the interesting thing with regard to this thread was that the SEM shows the groove is polished on 1st play by a low tip mass cartridge. Subsequent playings don't change this (TINY compared to the diamond) polished track much provided the tip mass remained low.
Above 1mg, the groove is irreparably & repeatedly damaged on each playing.
I leave yus pundits to explain the mechanism for this polishing and its relevance to clicks & pops 😀
If anyone has a copy of this booklet, it would be nice to have a copy on the WWW.
_____________________
Friction
Also in the early 70's, John Wright was working on the Audio & Design, mercury contact arm. He published an article in HFN on experiments with anti-skating.
He had a headshell which was pivoted so he could see if the anti-skating was correct.
What he found was that the anti-skating required varied with modulation and also the cartridge
Cartridges with small cantilever damping like the Decca needed less than those with more like the Ortofons.
'Skating' force is of course a direct measure of the 'frictional' forces at the tip .. at least along the line of the cartridge.
It may be Hans' MC cartridge has high midrange damping and hence would show little or no change in 'groove friction'.
I'm not sure how this tidbit helps the argument that 'groove friction' effects are a cause of ticks & pops but it might explain why he doesn't have any change in 'groove friction'.
Hans, can you tell us what is your cartridge?
___________________________
Lastly, in Jurassic times, I was a firm believer in wet playing.
The cartridge was usually a modified ADC XLM/VLM. This doesn't have an earthed cantilever (which the SHUREs do) and that is responsible for at least a few clicks from static when played dry.
I also had access to a KM record cleaning machine and used a Discwasher (IIRC) too.
___________________________
BTW, the mechanical response of a cartridge is complex. In most cartridges, there are at least 2 interacting resonant systems at HF close to each other.
One is the vinyl compliance against the tip mass.
The other is the cantilever compliance (what's usually quoted in specs) vs the tip mass again.
This leads to non-intuitive results like .. a stiffer compliance can often lead to better HF response, trackability, bla bla.
There's a number of SHURE papers in JAES which detail each new variant of V15 from Type II onwards which describe this.
Also a paper on the 'quad' M24 which details some of the tuning.
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Hi Kgrlee,
My feeling is also that the Cartridge and Arm interactions on the effect of playing dry/wet in this thread could be rather underestimated since nobody ever asked for it.
To answer your question, the cartridge I am using is a Benz LP mounted in a tangential arm, connected to a fully balanced Riaa preamp with a CMRR of over 90 dB up to 20 Khz.
Hans
Thanks Hans.
Anyone got a report of midrange trackability of the Benz cartridges? Eg the track of a test record where it give up.
This is one of the best indicators of 'compliance' damping.
LD, I note in one of your original posts that you didn't think the cantilever hinge had much to do with the effect we are discussing "clicks & pops due to friction".
But it certainly has a big effect on 'friction' along the line of the cartridge and how it changes with modulation.
I really should test mine, but as it sails through all my vinyl, including the direct to discs and the Telarc 1812 I marked it as 'adequate'.
Generally, I suspect a groove surface does get 'polished' by its brief interaction with a stylus during playback, at a molecular level visible only by SEM.
However, the whole concept of 'effective tip mass' is quite probably mistaken, at least in terms of it representing the inertia of the cantilever as a rigid body. It is conventionally measured by observing the 'top resonance' of a cartridge f response, typically resonant f falls in the range 12-30kHz - note that is entirely separate from any LCR resonant system, it is entirely mechanical.
It is then assumed that vinyl has a surface spring constant. Then its further assumed that the top resonant system is a spring-mass system, and knowing the resonant frequency allows the 'effective tip mass' to be determined.
However, a cantilever is not rigid by any means. It readily flexes, and a typical cantilever tube structure has a self-resonant flex mode at approx. the same frequency range as the observed 'top resonance'. The physics of vibrating beams applies, and the maths is well trodden for typical cantilever shapes and dimensions, and materials.
Therefore, it is not necessary for vinyl surface to spring during playback in order to explain effects such as 'top resonance' or harmonic distortion which are observed. It is better explained by cantilever flex, IMO.
Furthermore, since there is only one 'top resonance' (I lie, there is a series of hf eigenfrequencies exactly as one would predict from cantilever resonant modes), if cantilever flex explains the top-resonance then vinyl surface does not compress during playback.
A corollary of which is that 'effective tip mass' is a meaningless concept as defined and used within the industry for decades. It is just a restatement of the 'top resonant' frequency, which is determined by cantilever dimensions and materials. It has no bearing on trackability, other than that tracking content containing significant material near the resonant frequency is prone to mistrack - think Tacoma bridge.
Skate force arises because the ONLY direction the reaction force to stylus drag can be applied is along the line of the cantilever, and in an offset angle arm this creates a torque at the tonearm pivot.
Instantaneously, skate force equates directly to stylus drag force in total, including friction which can vary in itself. Skate force is therefore dynamic, and variations in the torque it generates are a significant stimulus for the cart-arm resonant system and headshell instability.
Cartridge suspension damping is typically all there is to damp the cart-arm resonance, aside from bearing losses and sometimes intentional damping. So more damping is good for headshell stability, and pitch stability arising.
However, more damping is bad for force required to move the cantilever/stylus. Damping force increases with modulation velocity, BTW.
A stylus is free to move in 2 dimensions. If required to move laterally by programme content, force to move a stylus/cantilever/cart suspension is applied by one of the grooves via a 45 degree wall angle. So there is an upforce associated with the reaction, which increases with force required to move the stylus/cantilever/suspension.
This is why higher damped cartridges require more VTF to track, or if one prefers why high compliance cartridges can track at low VTF. Compliance@100Hz is mostly determined by damping. Since the same elastomer provides spring and damping, damping and spring constant tend to correlate.
What's this got to do with tick/pops ? Friction, variation in it especially, adds to overall stylus drag, and consumes VTF budget otherwise used to hold the stylus in contact with groove walls. Ticks and pops are momentary loss of contact with groove walls, due to variation in friction, when not caused by contamination.
One is the 'top resonance' see comments above. There is only one! The other is an electrical LCR resonance in MM types. By design, these often are made to interleave and thus extend hf response in MM, and overcome LCR post resonant roll off for the audioband. In MC, often the top resonance is arranged to be above the audioband, but not always.
The resonance of the stylus mass against cantilever flex cannot happen, because the stylus is not free to move, groove walls are in the way. Except during mistracking.
Thank you for a very interesting post, kgrlee.
Seasons greetings one and all.
LD
From inspection of the spec for compliance and tracking force for that cart, IMO that is fairly typical of the modern genre and appears unremarkable in terms of probable suspension damping.
Aside, ye olde Japanese system for specifying compliance@100Hz was directly derived from measuring VTF required to track a certain velocity at 100Hz. Mechanical impedance of the cartridge suspension is mostly set by suspension damping at 100Hz, whereas at 10Hz it is mostly set by suspension spring. Sometimes, mechanical impedance plots versus frequency were published, derived directly from measured trackability.
Required VTF and suspension damping are well correlated, even today.
LD
I probably generalised in the sense that increasing VTF does not escape the friction trap: friction scales with VTF, and so does the 'threshold' at which friction force overcomes VTF and tick/pops micro-mistracking occur.
So cartridge suspensions, although they require various VTFs for a given trackability, don't help or hinder the friction induced noise tick/pop problem.
Naturally, the real world is not ideal and in practice there is some effect, of course. But not as great as the simple effect of stylus quality/shape/polish/alignment on friction coefficient, for example, IME.
LD
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Yes. Anyone have references to SEM photos? I'd very much like to see a copy of Walton's little booklet.
This has been known since Walton or maybe even earlier. As I said, there are at least 2 interacting mechanical resonances. The SHURE papers give chapter & verse. They include the cantilever beam resonances bla bla too.
This has been tested several times since the late 60s by Walton, SHURE etc. I remember an internal Engineering Memo by Don Barlow on his tests to see if one could assume a 'standard' value.
They are separate and both need considering .. especially if you are after supersonic response for a CD4 cartridge.
The true gurus, going back to at least Walton, knew all this.
Understanding some of this leads to the non-intuitive effects I mentioned. Walton used it to achieve 0.5mgm with cheapo stuff.
Probably the World's expert on this is Les Watts who did M24H for SHURE and IIRC, V15-V too.
IMHO, the important factor is HF trackability and you can use that to determine a 'nominal tip mass' for Marketing. But it is the trackability which is important.
Yup.
I bring it up as a much easier & finer measure of stylus drag than modifying turntables etc.
What do you think of my proposition that a cartridge with high mid damping may not show much difference in drag between wet & dry playing?
Makes it more difficult to measure 'friction ticks & pops' as the stylus drag due to damping would swamp it. What about an unmodulated groove?
________________
Seen any measurements on the effect of VTF on 'friction ticks & pops'?
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This has neatly linked into something I have been mulling the last few days and getting nowhere with on research. I nearly PM'd you to see if you had any links. One of the things I had realised is that, with some care, choice and spare money you can put together some interesting combinations of MM cart to meet whatever parameters you want. In particular you can (if so interested) get pretty much any stylus profile you want put on.
Example. Ortofon span the DJ and hifi worlds. Their DJ carts have compliance as low as 7cu, which is a pretty good match for some modern arms cw with 20cu of their hifi MMs. You could send a DJ stylus off to a retipper and get a sapphire cantilever and FG stylus stuck on*. On Paper this would give you a low compliance cart with a 'top of the line' diamond, but what would the VTF be governed by? The 3grams that the conical of the original stylus was set for, or a combination of that and the particular parameters of the profile?
*this is not entirely as mad as it sounds as this would still be cheaper than the OEM top end unit. It does however require a deep pocketed person to experiment with this as you might have to waste a few hundred here and there on frankencarts that don't work.
(as an aside, why are most MM carts still IIRO 20cu compliance when the popular tonearms are 10-12g effective mass and the ultra low mass ones are more than I would pay for a car or very old and in need of a good overhaul).
Example. Ortofon span the DJ and hifi worlds. Their DJ carts have compliance as low as 7cu, which is a pretty good match for some modern arms cw with 20cu of their hifi MMs. You could send a DJ stylus off to a retipper and get a sapphire cantilever and FG stylus stuck on*. On Paper this would give you a low compliance cart with a 'top of the line' diamond, but what would the VTF be governed by? The 3grams that the conical of the original stylus was set for, or a combination of that and the particular parameters of the profile?
*this is not entirely as mad as it sounds as this would still be cheaper than the OEM top end unit. It does however require a deep pocketed person to experiment with this as you might have to waste a few hundred here and there on frankencarts that don't work.
(as an aside, why are most MM carts still IIRO 20cu compliance when the popular tonearms are 10-12g effective mass and the ultra low mass ones are more than I would pay for a car or very old and in need of a good overhaul).
Dual had Antiskate meters. Like this Dual Skateometer. How accurate were these ? I suppose with accuracy friction can be reduced. Isn't it ?
High Compliance Cartridge : I read somewhere high compliance cartridges had more chance to damage record. How true is that? Wouldn't high compliance give more energy in high frequency response ?
Regards.
High Compliance Cartridge : I read somewhere high compliance cartridges had more chance to damage record. How true is that? Wouldn't high compliance give more energy in high frequency response ?
Regards.
A good question. The highest compliance cartridges were around 30cu and tracked at under 1g. They were touted as minimising record wear, but not sure how much real science has been done on that.
Note that compliance is confusing. Its how far the needle moves for a given input in um/mN. So a high compliance cart needs less force to move it. Which of course begs the next question 'so what'. which is one that would take a lot of maths to explain. (and understanding than I currently have) 🙂
Note that compliance is confusing. Its how far the needle moves for a given input in um/mN. So a high compliance cart needs less force to move it. Which of course begs the next question 'so what'. which is one that would take a lot of maths to explain. (and understanding than I currently have) 🙂
From my own work, and 3rd party extended f response plots eg from Shibata associated with decoding SQ quad carriers, there typically appears to be two distinct mechanical response peaks. However, if one examines the relationship of the ratio of frequencies involved, it closely follows an Eigen series law, the same as that governing modes of vibration of a single beam.
Beams, such as a cantilever, can vibrate in various modes, each mode with its own frequency, forming a series of resonant response peak and troughs in mechanical impedance versus frequency. IMO it appears as though and hf audioband/ultrasound sweep below 60kHz typicaly reveals the first 2 available modes of self-flex resonance for a cantilever. IMO it is probably a single resonant system, rather like a tubular bell, having a series of modes.
Not all cantilever vibration modes are available. For example, the stylus end of the cantilever is not free to move, it is retained by groove walls. Neither is the cartridge suspension end of the cantilever free to move in some cartridges, whereas in others it is and is loaded by a significant mass such as the generator.
My point is that, IMO, it isn't necessary to assume any vinyl spring to properly explain the phenomena observed. It's inconvenient, and contradicts the apparent singular system observed, if vinyl were to spring. IIRC Dr Barlow et al measured/analysed static spring behaviour of stylus/vinyl indentation, and assumed that applies. However, dynamic behaviour of vinyl indentation is a very different beast, and there are good energy reasons to consider that it cannot and does not happen. IMO, for practical purposes, vinyl probably behaves rigidly during playback, but cantilevers flex.
Aside as a footnote: there are also torsional flex modes of a cantilever, which are theoretically high ultrasound and never show up IME. There's also a theoretical torsional resonance of a cantilever as a rigid body with the torsional spring of the cartridge suspension that never shows up....
Yes, this is true.
By measuring trackability versus frequency at a given VTF one can deduce mechanical impedance seen by the stylus, ie opposition to move the stylus at a certain velocity. This was done by Shure, Denon, JVC and others and I have a few plots if I can find them.
At hf, mechanical impedance is assumed to be determined by moving inertia, and so one can deduce 'effective tip mass'. However, that assumes a cantilever is rigid, which isn't a safe assumption IMO. If it were true, increasing VTF would be the obvious way to continue to improve hf trackability, which Shure's cartridges certainly demonstrate otherwise.
Furtrhermore, at hf, mechanical impedance presented to the stylus mass to keep it retained tracking is mostly governed by cantilever mechanical impedance, ie flexibility. Increasing VTF therefore has little effect beyond a certain point, because flex of the cantilever is mostly what determines hf trackability.
In terms of using hf trackability to determine moving inertia at a certain VTF, what one is really doing is measuring cantilever mechanical impedance, ie flex and self mass properties. Typically, it's all about the cantilever, except for a single dominant property of the stylus: friction coefficient.
IMHO !
As to measurement of effect of VTF on crackle-pop noise, from my own measurements any effect is small enough to be not worth noting unless using VTF so low as to be below the threshold of useful trackability - at which point crackle/pop surface noise is significantly elevated. I think this is revealing about the mechanism, and IMO suggests the threshold for mistracking due to friction induced events typically scales with VTF, as does friction itself.
Thanks again for a very interesting post.
LD
It's on my list to transplant a nice nude Ortofon stylus into an S-120 suspension......it should work and I predict will have the lf/mid range trackability of the S-120 and the hf trackability and performance of the nudey derived from its cantilever, plus the friction benefits of the decent quality nudey stylus. Waiting for providence to supply the parts !
Because 20cu compliance provides just enough damping for stability in most arms, whilst retaining enough instability for true character ?
LD
Thanks, that's interesting Hiten. Yes, indirectly one is measuring *µ the friction coefficient, much easier than stop time measuements.
LD
OK, tangential arm = no variation in skate force in response to variation in friction. Probably/possibly why you don't observe the signature significant change in lf stability associated with wet/dry playback ?
LD
Braver than I am, I'd pay someone. Looks a little frankenstein http://www.northwestanalogue.com/uploads/5/0/7/7/5077806/4895122_orig.jpg but interesting. I think that is FG profile on ruby.
Except most arms are optimised around lower compliance these days. Although I guess the range of 10-20cu covers most MM and MC in production. <google> Ah hadn't noticed that Ortofon are still on the high end of MC compliance at 15ish for most models. So they have MM of lower compliance than MC. 🙂
That would also be my guess since even with fresh lithium grease applied to the TT's spindle, I observe no difference between dry / wet.
If true it would mean that a tangential has at least some benefit over a more conventional arm, although it does not automatically mean that the sound is superior, but I'm quite happy with it.
Hans
I think the whole cantilever assembly, inc generator, is compatible between 2M series and OM like the S-120, and it's all one piece and straight. Just needs a steady hand and dead reckoning eyesight - I'd have to sober up for a time.....! I predict the outcome would be a low compliance cart that tracks superbly at high VTF and has very nice damping. Plus the upsides of the quality stylus/cantilever at hf/high slew rates. I sort of guess the experiment might expose either stylus wear issues or vinyl burn issues with fine line contact profiles at high VTF, but yer never know until yer try, especially as to friction upside potential? I'm passively looking out for a sacrificial nude elliptical like the 2M Blue which is basically very nice.
It's the wrong side of the cost/sensibility line for me just to punt money at it. It would be decadent though !
He is in microphone business now
L M Watts Technology
Re skating force vs modulation and different cartridges, see this resume:
http://brujic.gradjevinans.net/HiFi/ve_skating_force_and_antiskating.pdf
George