Thorens And Nagaoka Mp-200

the thin end of the wedge
ipapb

Post by ipapb » 17 Jul 2011 11:36

Nagaoka says static : 21 cu (supposed at 10 Hz) and dynamic : 9 cu (supposed at 100 Hz).
is the dynamic value that is the important one when using any spreadsheet like the resonance evaluator.
I dont understand : the evaluator used to détermine resonance arround 6 to 15 HZ, so rather static, IMO.

Hi

bastlnut
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Post by bastlnut » 17 Jul 2011 11:50

ipapb wrote:Nagaoka says static : 21 cu (supposed at 10 Hz) and dynamic : 9 cu (supposed at 100 Hz).
is the dynamic value that is the important one when using any spreadsheet like the resonance evaluator.
I dont understand : the evaluator used to détermine resonance arround 6 to 15 HZ, so rather static, IMO.

Hi
hallo,

that would be nice to be able to choose which value you want to use,
but it does not work that way.
the one you MUST use is the dynamic spec! there is no choice in this!
the rule of thumb is to multiply the dynamic @ 100hz with the factor 1,5 or 1,6.
this will get you to about 15cu @ 10 hz which is the standard used by the resonance evaluator.
this supports the observations made by many people that Nagaoka cartridges work better with mid and slightly heavier tonearms.
so i guess the rule of thumb does work in this case as well.
any methode you use to get a theoretical match is only an indication and no garantie that the combination will sound good.

regards,
bas

Guest

Post by Guest » 17 Jul 2011 12:19

Static compliance and dynamic@10Hz are virtually the same figure, determined by suspension spring constant. Either of these parameters can be used directly in most calculators to determine natural resonant frequency, in conjunction with arm mass.

Dynamic@100Hz has an entirely seperate meaning. It relates to VTF and suspension damping. There is no 'multiplier 'factor' that relates static/dynamic@10Hz to dynamic@100Hz. Rules of thumb, and calculators based on this are therefore quite often misleading. As in this case, where they apparently predict 15cu, but actual is 21cu. That's quite a bit out.

What's more, they're silent about amount of suspension damping present. Which can be a significant omission when it comes to evaluating arm matching, in conjunction with resonant f. More damping implies a more tolerant f match, as in this case.

My calculators use VTF range to associate static/dynamic@10Hz with dynamic@100Hz. And report damping. In cases like this, they produce predictions which better match reality/experience than other calcs and rules of thumb.

bastlnut
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Post by bastlnut » 17 Jul 2011 13:03

hallo,

absolutely not!
dynamic is one value and static is another and they are not interchangeable.
static compliance is almost always higher than dynamic compliance as well.
if you predicate any of your calculations on any other basis then all you have ever done is wrong.
again the problem of pushing numbers.
and all your unsubstantiated claims are obviously in error with your faulty thinking.

regards,
bas

Guest

Post by Guest » 17 Jul 2011 13:15

No, you're mistaken bas. In this case it's proven and verifiable.

Numeric values of static and dynamic@10Hz are virtually the same, and are pretty much interchangeable. Obviously, they have different meanings, but both are dominated by suspension spring constant. Pragmatically, dynamic@10Hz is the better to use, if both are quoted. If there is a large difference, then damping ratio is high, but that's not often seen these days.

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Post by bastlnut » 17 Jul 2011 13:22

i doubt that it is proven or verifiable.
i suspect it is only your theory, or rather wish dream that is making it so in your mind.
even if it was then the specs would always give 100% indication what a good match is,
and we know this not to be the case.

you can have the last word,
but it will still be wrong.

regards,
bas

ipapb

Post by ipapb » 17 Jul 2011 13:37

Numeric values of static and dynamic@10Hz are virtually the same
This seems logical.
I cant imagine a "static" compliance calculated at 0 Hz ! :shock:

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lini
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Post by lini » 20 Jul 2011 06:43

bas, lucky: 1.5 to 1.6 would seem a rather low rule of thumb factor for converting 100Hz-compliance - usually some 1.8 to 2.2 are closer to reality....

ipabp: There's no need to "calculate" static compliance - it's just a simple measurement. And yes, it really is at 0 Hz, 'cause otherwise it wouldn't be static - and usually only spec'ed for the vertical plane, so basically static compliance just lets you predict how far the needle will sink in under a static load/a certain tracking force.

Greetings from Munich!

Manfred / lini

Guest

Post by Guest » 20 Jul 2011 08:47

lini wrote:so basically static compliance just lets you predict how far the needle will sink in under a static load/a certain tracking force.
Hi lini. Yes, that can be its intended purpose. As such, throw involved can be larger than stylus tracing motion, it depends on the manufacturer. In which case, that figure can vary from 'true spring compliance', because of elastomer properties.

None of this is made easy by the lack of a defined standard. What one seeks to know is the spring constant, and damping factor. Defined for the purpose of evaluating the spring-mass system of the cartridge tonearm. Neither of which are often uniquely specified !

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Post by bastlnut » 20 Jul 2011 11:51

lini wrote:bas, lucky: 1.5 to 1.6 would seem a rather low rule of thumb factor for converting 100Hz-compliance - usually some 1.8 to 2.2 are closer to reality....

Greetings from Munich!

Manfred / lini
hallo,

in my experience it really works out to the rule of thumb of 1,5 or 1,6.
1,8 is quite higher than almost any sytem i have had in my hands and 2 or higher is just not reasonable, not even close to any cartridge.

i like lighter tonearms and would love the factor to be 2 or more.
it is just not the case, as much as it would be my wish.

regards,
bas

Guest

Post by Guest » 20 Jul 2011 12:19

It just illustrates there is no useful rule of thumb conversion factor. It varies significantly on a case by case basis, for clear and obvious reasons.

In practice, one can often 'get away' with wide ranging assumptions about the factor, because the matching outcome can be tolerant. But then one frequently ends up with 'exceptions', as is often the case. If one really seeks to optimise a specific case, with confidence, the rules of thumb conversion factors are pretty useless.

There is a far better way of predicting the match.

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Post by lini » 20 Jul 2011 15:46

bas: For example, the Denon DL110 and DL160 are close to factor 2 - and for quite a few Audio Technica MMs it's even higher.

Moerch suggests a factor of 1.5 to 2, btw.

Greetings from Munich!

Manfred / lini

ipapb

Post by ipapb » 20 Jul 2011 18:22

Moerch suggests a factor of 1.5 to 2, btw.
Yes, of course.
There is no need to have an arm/cartridge resonance frequency high-accuracy : inside the range from 8 Hz to 12 Hz is good, I think.

Hi

Guest

Post by Guest » 21 Jul 2011 12:26

Actually, I think this also illustrates the problem. What are we supposed to do, ensure the res f falls in range 8-12Hz for all known conversion factors say 1.3 to 2.2 ?

What if the result is marginal, say dodgy at 1.5, but OK at 2, what are we supposed to do ?

Not only is this not much use, but ignores the opportunity to evaluate suspension damping, and the overall damping likely to result from a cartridge/arm match. Which is a missed opportunity.

Compliance@100Hz comprises contributions from both spring stiffness, amd damping 'stiffness'. But only spring stiffness contributes to resonant frequency. And we don't know the ratio of spring/damping for any given cartridge. So there is no single 'conversion factor', that works across cartridges.

To convert properly, one simply needs to use VTF range, and the definition of compliance@100Hz. Then one can derive both spring constant, for resonant f, and damping coefficient, for damping ratio. And one can evaluate potential match for both res f, and damping ratio. Find out if, and how much, arm damping might be beneficial, into the bargain. Which surely is simply far better than common rules of thumb plus long list of exceptions, as I see it.

bastlnut
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Post by bastlnut » 21 Jul 2011 17:03

hallo,

what you say LD has a lot that is in the right direction, but....
why waste time playing with numbers when we can do it for real by tweaking...which is what that is....instead of pulling out hair making mistakes in theory.
if a tweak is made that is not an improvement or even worsens the situation, then it can be looked at, with numbers too, and another tweak or 2 will make it sound great.
an experienced tweaker will listen and know what to do without any stupid numbers.
those less experienced can ask one more experienced or start a thread on this forum.

playing with your spread sheets just wastes time and an inexperienced tweaker will still be none the wiser but the numbers look good as a place to start with.... :roll:
its like fear mongering, using the calculations.
oh, oh oh, will i get it right?
and in the end it is only a starting point that needs further tweaking.
then there are too many factors to know which to change and the user is in the classic situation of too many cooks.

this is why spreadsheets should be made with help of an experienced person who has good hands on knowledge.
you just have way too little knowledge and experience for your spreadsheet to be really useful.
apologize.

regards,
bas