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Tonearm “rigidity”: beliefs, myths and revisionism

Yank said:
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I always thought that was quite clever in that is was quite stiff torsionally but damped vertically. A simple and logical way to make a very cheap tonearm. I’ve never seen one properly, so no idea about the bearings, but I remember it being liked for its price.
 
Tony L said:
My theory is this is why the Aro, which being a unipivot does not have slop, sounds much smoother and more open across the midband to my ears.
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In the Aro manual, Naim emphasize that the various bolts, etc., in the assembly should not be over-tightened, particularly the bolt that secures the bearing pillar. I took pains to just barely nip it up, and to try and get the cartridge bolts "just tight enough", as well.

However, then I went and tightened up the driver bolts on my (front-ported) speakers. I wonder if I should loosen them back up again!
 
Tony L said:
I always thought that was quite clever in that is was quite stiff torsionally but damped vertically. A simple and logical way to make a very cheap tonearm. I’ve never seen one properly, so no idea about the bearings, but I remember it being liked for its price.
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My recollection is that they abandoned the flat arm and switched to a lightweight metal tube, probably aluminium. Bearing in mind the ease of manufacture of the flat arm, there must have been a reason for changing. Perhaps it was perception, but it may have been that the more traditional tube sounded better. I remember that you could easily flex the flat arm. I don't buy the flappy arm theory at all. It seems like a way to paper over problems (absorb resonances) elsewhere.
 
sonddek said:
My recollection is that they abandoned the flat arm and switched to a lightweight metal tube, probably aluminium. Bearing in mind the ease of manufacture of the flat arm, there must have been a reason for changing. Perhaps it was perception, but it may have been that the more traditional tube sounded better.
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I definitely remember it changing. My recollection was it was public perception, people just didn’t like the look of the flat ones, though IIRC reviewers felt the flat one sounded better. There was a heck of a lot of dogma around at that time as the flat earth “rigidity” thing was just starting and a lot of people still assume what they feel in the hand, see, think etc has any relevance to how something actually behaves at 20Hz-20kHz, which obviously it doesn’t. I have no direct experience with the deck at all, but I got the impression the original design was proper science rather than marketing and that rather more thought had gone into stiffness in various planes, keeping the resonant frequency out of the audio band etc. I only remember it at all because it struck me as a rather clever piece of lateral thinking. It was after all only a budget turntable, Dual 505 level IIRC.
 
Tony L said:
I’m prepared to bet that at audio frequencies the Well Tempered is vastly more rigid than the Ekos and what you preferred was actually a resonance! Any arm with bearings has slop, if it didn’t it couldn’t move, i.e. even the high quality bearing races Linn use will have movement in every plane. My theory is this is why the Aro, which being a unipivot does not have slop, sounds much smoother and more open across the midband to my ears.
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I’ve heard a WT deck in my system, it was superb. I’m afraid your thoughts about the bearings and effect on sound are not correct in respect of Linn.
 
flatpopely said:
I’m afraid your thoughts about the bearings and effect on sound are not correct in respect of Linn.
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Please show your evidence! I’m not singling out Linn, it is the same with any conventional bearing arm. If they had no play they can’t move freely, simple as that. Sure, humans won’t be able to feel any slop in an ABEC 5 or 7 bearing, but it is there on a microscopic level as it has to be for the thing to have low friction. This is not the case on a unipivot, a WT, Schroeder and some other non-conventional designs. These work with a different rule-book.

PS FWIW the old Linn arms have a distinct sound to my ears; the Ittok having a pretty obvious resonance/forwardness in the upper mid (the reason I later went to a Zeta), fun and very tuneful though. I never got on with the Ekos in dems, very easily beaten by the Aro to my ears/taste, though in fairness I never heard the MkII.
 
I once had some Yorkshire Hi Fi 1.3 speakers (they were very good) and they provided pieces of self adhesive foam to place between stand and speaker.. seemed to work....
 
Tony L said:
...a lot of people still assume what they feel in the hand, see, think etc has any relevance to how something actually behaves at 20Hz-20kHz, which obviously it doesn’t.
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I suspect that behaviour below 20Hz is also critical for turntable parts. A 5Hz or 0.5Hz oscillation, even at a duration of half a cycle, will have an audible and possibly deleterious effect on accurate reproduction. Think of the 0.55Hz effect of eccentric record holes. Nasty. I'm almost tempted to suggest that what happens below 20Hz is even more important than what happens above when it comes to tempo, timbre and tunes.
 
Isolation of a cartridge from an arm would be a blob of blutac or a similar material and nothing else, no mounting screws, nothing.

Finger tight still means that there is a contact between two masses that vibrations pass through. It is damped, not isolated by blutac or felt, whatever.

Tighten until it screams was always yet another piece of Linn marketing bollocks. If you tighten something until the materials distort then you've weakened the materials.

Marketing departments are the last people to be told the ideas behind something and the very last to tell you about them in any comprehensible form.

I think that high-end turntables are the result of a few guiding principles but a much larger amount of tweaking and bodging towards what that designer thinks is a good sound.

I've come to the conclusion that I have no idea what I'm doing other than buggering about with a highly tuned instrument. I've always let someone who has been trained handle my LP12.

I say that if you don't like it, change it for something made by another designer that you like better. Or take your turntable to another dealer and see what they think.

You haven't done the studying or spent the hours and hours of experimenting with different materials and methods. Play around with it all you like, but don't pretend that you know what you're really doing.
 
I live in fear about the not over-tightening instruction. If I can’t use a torque wrench I wreck everything. I had to replace some plastic plumbing a few weeks ago, my head sweat produced more water than the leak did!
 
2ManyBoxes said:
Isolation of a cartridge from an arm would be a blob of blutac or a similar...
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No it isn't, that's the point. Water is 'soft' but hit it fast enough and it might as well be concrete. We're looking at materials in slow motion compared to audio frequencies.
 
AndyU said:
There’s maybe similar arguments about speaker stands. The hifi standard was rigid, spiked coupling into the floor, whereas pro studio builders like Northward Acoustics go for elastomeric and spring decoupling between speaker and stand, tuned to around 8Hz.

https://lydmaskinen.dk/viewtopic.php?t=76917
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These different approaches to coupling have different effects depending on many factors including the mass and material of the devices, and which part of the audible range you are concentrating on.

I have heard, and I still think I didn't imagine it, more rigid coupling of speakers with spikes opening up soundstage by more accurate/cleaner high frequency acoustics. I think I've heard more rigid coupling produce a tighter more extended/tuneful bass too.

I'm not saying greater freedom to move can't solve particular problems in certain parts of non-ideal systems, but it may introduce others, depending on a wide range of factors.

It seems to me to be a matter of principle that ideal transducers in an ideal environment will be fixed firmly to minimise the 'doppler effect' caused by parts moving when they shouldn't. The real world may not work exactly like this, but the most accurate turntable and speaker components have been moving in the direction of higher rigidity for 100 years. Progress in accuracy has been significant.

I'm standing up for rigidity and accuracy. I think a turntable is not a Stradivarius - it can aim to contribute the least possible distortion to the signal.
 
I was recommended to try the Origin Live "Cartridge Enabler" which looks like a similar idea to the Funk Firm product. I may still try it (as it's relatively inexpensive) but wasn't sure it was compatible with the tonearm designer's intent. Rega for example design their turntables and tonearms as "vibration measuring" devices and Roksan also promoted their hardware as "groove measuring" devices so would imagine a firm cartridge mount would be consistent with this as opposed to a more compliant mount. I believe Touraj Moghaddam had looked at an integrated tonearm / cartridge when he was at Roksan but discounted this on practicality and cost grounds. Presumably in their choice of materials, finishes, bearing designs, mounting design etc etc all have considered how to address resonances originating from the cartridge. SME's tonearm tubes I believe are magnesium and are tapered along the length of the tube to reduce the potential for resonances. The Artemiz tonearm I use has had various finishes in the product lifespan and employs a decoupled counterweight and interference fit where the armtube joins the bearing yoke. All considerations that would be consistent with the rigidity approach.

As others have said, overtightening of the cartridge bolts amongst other things, could also potentially damage the arm especially if it has not been removed from the turntable so I tend to agree with the "tight enough" approach. TL's post has also got me thinking whether the 3 point cartridge mount employed in say the Linn Troika and now in some of Rega's MC cartridges are about alignment or about achieving a strong coupling between cartridge and headshell.
 
This isn’t something I’ve ever given a great deal of thought over; I am pretty happy with my LP12 & prefer not to fret about the intricacies of its set up.
 
sonddek said:
I'm standing up for rigidity and accuracy.
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You are standing up for your specific grasp of ‘rigidity’ and your perception of ‘accuracy’. Mine is rather different, e.g. I’m prepared to bet that WT is a lot stiffer where it matters than many of the conventional arms that are sold (usually visually) as being “rigid”! We are dealing with audio frequencies here, it isn’t a bicycle fork!
 
I'm not an expert, certainly not on transducing systems like this, but potential points.

- A tonearm will only be rigid to the tube's first bending mode (a couple of hundred hertz or so). Up to that point, the arm tube may couple the cartridge to vibrational energy transmitted via it (e.g motor noise). Hence there's a case for isolation.
- The cartridge will be rigid to its natural frequency and should become a stator around twice that. At that point it should be isolated from the arm and if isn't broadly the case, then the cartridge would work at all.
- If frequencies above this 'stator' frequency transmit through to the arm, then the damping at the cartridge is imperfect or poor. As these dampers tend to be blobs of rubber that a) crude and b) degrade then this seems likely.
- There seems to be a case for better damping techniques in cartridges or at least applied at the cartridge end of the arm. We need a Citroen!
- Each bolt size will have a 'standard torque'. I'd just use that. Maybe even, if there are two fixing bolts, take one to standard torque and do the other one up so it doesn't 'chatter' and no further.

But as I say, I'm no expert.
 
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