There are several ways to estimate tonearm effective mass, but none of them are really simple to do. Safe to say that the static weight of the headshell is a factor, but not simply by the ratio of its static weight to that of the stock FR64S headshell. Best way to approach this, in my opinion, is to try it. You might also acquire one of the test LPs that permit estimating resonant frequency. From that information, you can calculate effective mass of the assembly of tonearm, cartridge, headshell, screws, and the counter-weight at the rear.
Another trick: If you think of the tonearm as a seesaw, with the counter-weight on one side and everything else on the other, then you can get at effective mass by balancing the tonearm such that the arm is hanging level in space, zero VTF. Now measure the distance from the pivot to the center of mass of the CW, in centimeters. Then remove the CW and weigh it separately, in grams. The effective mass will be related to the product of the square of the distance from the pivot point to the center of mass of the CW times the weight of the CW. Now, if I can only recall HOW the two are related, you'd be in business.
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I don't know where to begin. If VE says that the OEM FR64S + its OEM headshell have together an effective mass of 35g, that's a good place to start. Then you have to add the weight of the cartridge and the screws and nuts used to hold the cartridge in place. But you'd like to know the weight of the OEM headshell separately, so as to be able to compare it to the weight of the Orsonic, like Raul says. And even then, the change in EM is not the same as the difference in static weight of the two objects. (I don't know what a Decca pod is. Perhaps it's something that goes between the headshell and the cartridge. If so, the pod plus Orsonic might be close to the same weight as the OEM FR headshell. The difference would be negligible, IMO.) If it sounds good, especially in the low bass region, it probably IS good. If the calculated resonant frequency is 7.5Hz, that is not so bad either. You might look here for some help: http://www.resfreq.com/resonancecalculator.html |
Raul, What do you consider proper dampening of tonearm resonance? I was thinking on this subject. There are different methods adopted by different manufacturers. For example, the Triplanar has that elliptically shaped silicon bath mounted on the pillar near the pivot point (and the Triplanar arm wand is wrapped in a shrink-tube-like material), whereas Townsend is alone in providing the damping up near to the headshell, where perhaps it is most needed. Still others, particularly unipivot designs, provide dampening right at the pivot point. And Technics has that resonance control device built into the counter-weight side of the pivot. Further, dampening can be achieved by the choice of material used to make the arm wand. (We know all to well that you do not like the steel FR tonearms, for example.) One potential virtue of wood tonearms in my mind is the very fact that wood, being a natural amorphous material, will tend not to display a sharp peak at resonance and will tend to dissipate resonant energy rather than transmit it. For whatever reason, I find that I have tended to like wood tonearms. I have heard carbon fiber tonearms, and without exception I have found them to be not to my liking; the sound is dull and lacking in sparkle that I associate with real live music performances. This subjective impression suggests to me that it is not only dampening per se that counts; HOW you achieve dampening may also be critical.
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Raul, Audio is not an exact science. In fact, it's not a science at all, and logic does not always predict what will sound best. Thus, while I take your point on damping or "dampening", I still can listen to my FR64S and say "Holy Cow that's good". I am trying to do some research on why it does sound good despite the problems you cite. One possible saving grace of my set-up is that I have the FR64S mounted in its B60 base adjuster, which adds mass closely coupled to the arm structure, and the B60 is in turn mounted into a massive aluminum arm board that is one piece with a bigger piece of alu bolted to the bottom of the plinth. One theory is if you give the mechanical energy a good pathway into a high mass object, the energy will dissipate as heat without the ability to induce motion. It's really dampening by another mechanism. I don't insist this is true; it's just a thought.
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cleeds, While Raul’s English may be a bit fractured at times, he is never "confused" about any of his underlying beliefs, as I am sure he will soon tell you, where the FR64S is concerned. But I agree with you; I set mine up expecting the kinds of problems Raul has repeatedly described, but I don’t hear them so far. In fact, I am breaking other rules as well, using a high mass arm with a high compliance cartridge (Acutex LPM320). I am still giving Raul the benefit of the doubt, because I do respect his opinion, except when he accuses me of "liking" distortions. Before I draw final conclusions I need to replace the 64S with some other tonearm that is both lower in effective mass and higher in "dampening" characteristics, keeping the turntable (Victor TT101 in re-enforced plinth) and cartridge constant.
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Nicola, You raise an interesting question: I wonder how many of us now own or ever did own an FR64S or FR66S. And among this group, what is the opinion of the tonearm in terms of sonic qualities?
I will start by saying I own one and my opinion so far is positive.
(I think the voting among FR64S or FR66S users can be simplified to "positive" or "negative".)
Maybe this should be a separate thread, but it does relate to the OP's conundrum. Nevertheless, if he would rather squelch this investigation, so be it. |
As I implied in one of my responses to Raul, I think the coupling of the tonearm (any tonearm, but maybe especially undamped tonearms) to high mass is another form of dampening. So, you're on the right track, IMO. |
"FR adjustable VTA base" = B60, to which I referred. Using it has the non-obvious advantage of adding mass to the arm by virtue of its close coupling to the vertical shaft of the arm proper. To add even much more mass, I created an aluminum arm board that is in turn connected to a second massive piece of aluminum bolted to the bottom of the plinth, via a half-inch diameter bolt that joins the two. So, from the headshell all the way to the mount, there is solid metal which should facilitate the transfer of energy away from the cartridge. This could be just mental masturbation on my part, but it does sound good, and I hear none of the problems cited by Raul. In fact, the outstanding characteristic of the sound is that it is very "clean", no evidence of a resonant signature in the treble or anywhere else. But I do take Raul's comments seriously, because he is a careful listener, albeit he listens to a system quite different from mine. (By the way, I too am using a light weight headshell; I think it's magnesium. The cartridge right now is an Acutex with very high compliance; I was expecting the worst from this combo but got something great.)
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Raul, As I mentioned once before, the cartridge I am running on my FR64S is an Acutex LPM320STRIII. Acutex say the compliance is 42; I forget whether that is a static or dynamic measurement and at what frequency. I also own the snub nose earlier version M320, but have not tried it yet. Yes, it is a great cartridge. I wonder whether paradoxically MM or MI cartridges like the Acutex might actually work BETTER than MC types on an undamped tonearm such as the FR64S, because the MCs are said to put more energy back up into the arm wand, perhaps due to low compliance. A high compliance cartridge is acting like a good auto suspension to minimize energy that might go back up into the cartridge body, and therefore there is less need for damping the tonearm proper. Plus, I said my piece on mass loading. Just a thought.
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CLeeds, In all fairness to Raul, where do you go these days to buy a NEW FR64S? In fact, so far as I know, Raul has owned his FR64S for a much longer period of time than I have owned mine; there's at least a chance that he DID buy his FR64S new. I would wager that nearly all of us who have commented on this thread bought their FR tonearms as used items. I bought mine off eBay about 3-4 years ago, with "silver inside", from either 2juki or one of the other regular Japanese eBay sellers. When I got it, the bearing was a little stiff. Dertonearm advised me to just leave it in a warm place so as to allow the bearing lubricant to warm up, and indeed he was right; the problem just disappeared while the FR64S was sitting at room temperature in my house. Other than a broken internal wire or a very stiff bearing that does not "thaw out", I don't know what else could go wrong with an FR64S that would not be immediately apparent. Thus I conclude that Raul's opinion, whether we like it or not, is based on listening to a fully OK sample of the tonearm.
By the way, I am wondering whether the lubricant that evidently surrounds the bearing in fact does constitute a form of damping |
