from tear downs I have seen there is not a tie wire. But I may have to sacrifice one for science to confirm.
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One interesting snipped I found out last night is that the DJ cantilevers as shown above are not a single tube, but in fact two concentric tubes to give added studlyness. This should make is supremely stiff, but sadly also somewhat massive.
AFAIK the S-120 doesn't do that: rather it's a fat tube, which is the best way to use a mass budget for max rigidity, in a given material.
There is also an argument that the last thing one wants is a rigid cantilever, because then the moving mass is the whole cantilever, rather than the end section that bends....... And suddenly we're back to mechanical transmission lines, providing a low impedance connection at the stylus end, to the high impedance mass of the generator.
IME, extreme hf trackability of the S-120 is very good, but can be outdone by some cantilevers which on the face of it are less rigid. But then, they also have different profile styli with perhaps better polish/finish? Though the S-120 looks good microscopically IME, it is bonded.
IIRC there's a slight uplift at 18-20kHz when an S-120 used with Aurak, which perhaps suggests that's the mechanical resonance is c 20kHz ??
A very good, cheap, and safe, starting point to explore transimpedance loading is the S-120, IMO. Collectively, that should challenge enough icons as to how such an inexpensive thing can perform that well to keep one busy for a few years !
LD
Hmm Interesting. Comes back around to the cantilever on the ortofon Rohmann which has the most aggressive taper I have seen.
A few months ago I was chatting to Dominic and NorthwestAnalogue, mainly as he can obtain the Gyger FGS profile which I was interested in. He has his own cantilever material, which I didn't give much thought to at the time and he said it was 'more flexible that Boron but sounds better'.
Certainly the 'telescope' designs that were popular back in the 70s and 80s make more sense if you are right.
A few months ago I was chatting to Dominic and NorthwestAnalogue, mainly as he can obtain the Gyger FGS profile which I was interested in. He has his own cantilever material, which I didn't give much thought to at the time and he said it was 'more flexible that Boron but sounds better'.
Certainly the 'telescope' designs that were popular back in the 70s and 80s make more sense if you are right.
Yes, makes sense in this context. As does tapering. Though the focus of attention was always on reducing moving mass as though it were a rigid body, actually the side effect is to make the stylus end more flexible, and so lower mechanical impedance as seen by the stylus.
LD
It is certain that Shure's engineers were well aware of cantilever flexibility and modelled it, as shown in L.R. Happ's Design Considerations of the Vl5 Type IV Phonograph Cartridge available on Shure's website (here: High Fidelity Phonograph Cartridge - Technical Seminar | Shure Technical FAQ)
These design techniques were widely available at the time and I wouldn't be surprised if other manufacturers used similar approaches. Wouldn't it be grand to have access to AT's design archive ....
High Fidelity Phonograph Cartridge - Technical Seminar | Shure Technical FAQ
Thanks for this bondini.
It summarizes in very digestible form, nearly all the SHURE stuff I remember from their AES papers.
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Lucky, it describes the essential stuff on the M24 which Les Watts worked on.
The only thing missing from the papers are da fan C eqns which i dun pre10 2 unnerstan anyway.
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It is also the only source outside our R&D Dept that I've seen mention the importance of earthing the cartridge/cantilever. They still miss out that the platter has to earthed too to take full advantage of their brush.
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And it also states that higher compliance can "actually degrade the playback of high frequencies".
Thanks for this bondini.
It summarizes in very digestible form, nearly all the SHURE stuff I remember from their AES papers.
_________________
Lucky, it describes the essential stuff on the M24 which Les Watts worked on.
The only thing missing from the papers are da fan C eqns which i dun pre10 2 unnerstan anyway.
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It is also the only source outside our R&D Dept that I've seen mention the importance of earthing the cartridge/cantilever. They still miss out that the platter has to earthed too to take full advantage of their brush.
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And it also states that higher compliance can "actually degrade the playback of high frequencies".
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No. Les Watts was very American and worked on many important SHURE cartridges including M24 & V15-V.
He now designs & makes microphones.
The L M Watts Technology Polyribbon Microphone Story - ProSoundWeb
L M Watts Technology
Thanks, Richard. I think Shure published these summary articles as part of their marketing material, and much of it has stuck as being an irrefutable source, unfortunately IMO, because much of it doesn't stand scrutiny or has unsatisfying explanation, IMO.......
That said, I think the section on cantilever flex suggests some people at least within Shure knew what was at issue. The novel step I think they perhaps missed was to consider the cantilever a mechanical transmission line: the models they built used lumped parameters, albeit in multi sections. These days we are blessed with desktop tools that make analysis readily possible, whereas it was a significant task back in the day no doubt.
In the full article, IIRC, to reconcile theoretical cantilever model with reality, it assumed boundary conditions involving 2 spring constants: cantilever flex and vinyl elasticity. There was two orders of magnitude difference between them, and they assigned with vinyl elasticity being significantly more compliant, as was the belief. I calculate it to be the other way round, based on classic beam bending as already posted.
Empirically, I think they found a right answer in the V15, perhaps for the wrong reasons. The clue is when tip-mass is used as a figure of merit, which could be marketing of course, rather than tip-spring. Each expresses mechanical impedance as seen by the stylus, and low figures are good for trackability. But low tip-spring means flexibility, and sets different design goals methinks. Perhaps some people understood, or perhaps it's yet to be explored............?
One thing that IMO can't be right in that article section, is Figure 1. Which publishes observed peak programme material versus frequencies, and trackability limits. For example, c 40cm/s@10kHz, which, for reasons set out in the Neumann cutter manual already posted, is uncutable and untrackable, even on outer grooves. Peak stylus acceleration would be about 3800G........(!)
LD
As I said, I better not stir the pot in case the vinyl flex deniers jump down my throat 😀
The reason for using a stepped model was simple. Even the most advanced FEA models didn't have 'transmission lines' and I think the SHURE model was a home grown Fortran item. I think they increased the number of sections until some sort of convergence was observed.
In speakers, it wasn't until Patrick Macy did the first BE for PAFEC air that you could avoid having to mesh your whole room to get sensible results for 'free air'. This was in the early 1990s. I was involved in Beta testing the model.
IIRC, if you read the original paper, these spot frequencies (which certainly couldn't be tracked by any cartridge at the time or even today) were determined by optical examination of the actual records.
Some were from the Sheffield Direct Cut discs which were done with various limiters disabled. (There are severe built in slew limits for tape recording too ... some of which are much more objectionable than vinyl slew limits)
There's the 'degree' of mistracking which applies even if the track cannot be tracked perfectly.
At HF, the most obvious is 'sss' becoming 'tshh'. Cymbal crashes are probably the most demanding but actually its vocal sibilants that are most annoying ... but much less obvious to those unversed in the art than MF & LF mistracking.
Anyone still got unplayed copies of the various SHURE Obstacle Courses?
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Ha! The cantilever flex deniers will have decades of assumptions to retract, come the revolution 😉
Is that even possible in programme material ? I doubt it. Velocity is encoded by instantaneous groove angle, and frequency by period. In a complex waveform from programme material involving content at all frequencies, I'd say it was impossible except by spectrum analysis such as FFT, which is certainly not a visual process !
If it was visual, then it's probably not valid and that might explain the matter?
Yes, I have all the good ones, still in good condition. I even found them again, having gone missing, last week !
LD
la Spagna One of Stan Ricker's Final Cuts is a Gift to Audiophiles | Analog Planet
Apparantly Stan broke a cutter head trying to cut this without limiting. As the CD was £10 I declined £45 for the double LP especially as its not something you'd listen to every day.
Apparantly Stan broke a cutter head trying to cut this without limiting. As the CD was £10 I declined £45 for the double LP especially as its not something you'd listen to every day.
I'm not sure that is the case - I take Figure 5 in the Happ article as just the sort of thing a mechanical engineer would sketch to model a shank composed of a succession of tubes and rods. The analysis could then be conducted in a number of ways, ranging from lumped parameter analysis through to finite element analysis through to explicit solutions based on one or more parameters of interest. While I couldn't find a description of Shure's analytic approach in the article, I was working on vibration problems at the time of those articles - it is just the sort of problem for which I would have developed an explicit solution in FORTRAN ... punched into a deck of Hollerith cards.
Figure 5 in Happ's presentation assigns an impedence Z to vinyl, which would include damping along with compliance - I would do likewise. Could you point me to the full article?
Shure were rather adept at actually measuring parameters - it would be interesting if they cited the source of their data.
Probably homegrown, probably FORTRAN; could have been explicit, could have been finite element. Scratch most finite element routines hard enough and you'll find the original FORTRAN coding. In the world of mechanical engineering, we wrote most of those models between 1976 and 1986.
No reason to deny cantilever flex. It's essential that it occurs. Or something is very wrong with the Newtoniasphere.
IIRC from the full paper, FORTRAN was the weapon of choice and extracts from the code were published. The output plots were a series of * characters on a line printer. Unfortunately, I can't find my full copy, but everything is somewhere.........it'll turn up.
Only if vinyl groove wall indents/moves........😉 I did write a critique of it once, that no doubt went south in the great purge.............
LD
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Actually us advocates of vinyl flex believe in cantilever flex too.
Its yus vinyl flex deniers who are fanatical fundamentalists 😀
Actually its quite easy. If you have played with the SHURE Obstacle Courses with various cartridges, you learn to recognise the sound of HF mistracking and you take a travelling microscope to those grooves on a new disc.
Cecil Watts did this in the 60s. Mono IIRC. And so did Don Barlow. Many his pics in our Engineering Memoranda were of lacquers.
Yes. You are looking for groove angle and you'd get the 'frequency' from analysing the mistracked signal. The SHURE data has limit lines for stylus radii which of course correspond to groove angle & 'slew rate'.
My dim Jurassic memory has popped up that Don's caveats about letting Test Records recover before doing another run may be for the frequency sweep lacquers he had specially cut rather than the CBS and B&K ones.
Is no one with a test record going to do 2 sweeps, one after another to see if this caveat applies to vinyl ? 😡
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Well, neither of them need be offended by the concept of dynamic elastic behaviour being very different from static behaviour.
AFAIK there is no published analysis of the dynamic behaviour of the stylus as it traverses 250000 times its own contact surface of groove per second. I've analysed it from energy considerations, from which there are obvious contradictions which only go away if identation is effectively zero, as close as makes no difference.
Much as I hate analogies, consider a bowling ball sliding at supersonic speed over a giant trampoline surface. There is neither time, nor energy, for the surface to indent, and the trampoline effectively behaves as a rigid plane surface. So it is, IMO, with stylus-groove motion.
When there is no indentation, or very small, the physics/mechanics hangs together IMO, which otherwise it doesn't.
The phenomena generally attributed to vinyl indentation, such as tracing distortion, are just as well described by cantilever flex alone.
And, the observed series of resonances is better explained by modes of cantilever vibration: it's not necessary to include a separate vinyl compliance, IMO because there isn't one unless the stylus is stationary (!)
LD