When Does A Tonearm Have Medium Effective Mass Etc

[bastlnut]

hallo SF,

hadbags, huh? LOL
i agree that LD is good with math.
i have even said so many times.
i suggested that he includes observation and real world practice and experiments to refine and/or validate his calculations.
if all his work is only as good as using a rule of thumb, then why the effort?

regards,
bas

[Ldg]

then why the effort?

Why the effort ? For a starter, the effort exposes myths and imaginations you confidently assert, to be pure bunk, bas !

Pretty obviously, such tools readily allow simulation of all kind of 'what ifs' that are not feasible to try practically. And to settle on configurations most likely to succeed. But you neither understand the tools, nor the underlying principles, bas. Your loss.

It is obviously important to you that analysis and proper understanding is suppressed, bas. It might expose much of the nonsense you post for what it is. Imagined, baseless, evidenceless rubbish.

It's really obvious that real world practice and experiments are an integral part of developing my calculators. You can see many examples of refinements and/or validation in various threads concerning the calculators, based on feedback. You can't fail to know this. But hey, if you don't try them, you'll never know

[bastlnut]

then why the effort?

Why the effort ? For a starter, the effort exposes myths and imaginations you confidently assert, to be pure bunk, bas !

Pretty obviously, such tools readily allow simulation of all kind of 'what ifs' that are not feasible to try practically. And to settle on configurations most likely to succeed. But you neither understand the tools, nor the underlying principles, bas. Your loss.

It is obviously important to you that analysis and proper understanding is suppressed, bas. It might expose much of the nonsense you post for what it is. Imagined, baseless, evidenceless rubbish.

It's really obvious that real world practice and experiments are an integral part of developing my calculators. You can see many examples of refinements and/or validation in various threads concerning the calculators, based on feedback. You can't fail to know this. But hey, if you don't try them, you'll never know

hallo LD,

yes tools are important. tools are something i am very fond of.
i have tried your version of the tools you linked on your website and this must have been before the refinements.
because of m experience i can do what the tools can without them.
true, most can not.
my biggest issue with any tools is the weaknesses.
based on what you stated about what is important and what has little effect,
i have seen that you can come to wrong and very wrong conclusions.
this is my issue with your version.

a further issue is that society has been trained to look first at numbers and scientific methode rather than there own instinct and common sense.
using both is the best option but we have been taught not to trust ourselves.
so to rely 99% on tools is a problem when the tools ignore things so are incapable of including what is not referenced in the calculations.

taking issue with a rule of thumb because it does not use a tool, or one of your tools is short sighted and arrogant.
if trusting ones self is myths and imagination then i feel really sorry for you.
your refusal to try what you assert is suspect in itself.
this is why i call it hiding behind numbers.
society has been trained to trust numbers.
it is even more tragic that we know that people can use numbers to lie,
make claims that are not accurate and confuse, to help sell something,
but people ignore that fact.
it is just how we are trained via newspapers, films and fear.
you use the tool of numbers, that we have been trained to blindly accept.
with that use, comes the responsibility of selflessness and the need to make sure it is as complete and accurate as possible.
i am not saying that you are doing that.
i am saying that you are ignoring important aspects that could make your version of the tools more valuable.

regards,
bas

[Ldg]

....because of m experience i can do what the tools can without them.
true, most can not.......

You might well believe that bas, but no. For starters you have to understand principles and interactions. From this thread it's evident you don't even grasp basics such as tonearm effective mass and compliance, bas. Let alone how they interact. Then you have to solve reasonably complex equations.........by instinct.........come on !

i have seen that you can come to wrong and very wrong conclusions.
this is my issue with your version.

Or you could well be wrong again, bas If you care to cite an example, we can resolve it, bas. To my knowledge, current versions of all calculators work well. You've never posted feedback of any discrepancy, bas, IIRC.......pretty likely you're wrong again, bas

your refusal to try what you assert is suspect in itself.

What ? Not just me, but many VE members use and provide feedback on the various calculators.

it is even more tragic that we know that people can use numbers to lie,

This again implies i could be lying. The second time on this thread. I find this thoroughly objectionable. It's baseless, and false. But coming from you bas, who couldn't tell the difference anyway, it has no meaning. The calculators mimic reality pretty well, that's the acid proof.

[Ldg]

Here's an illustration of cartridge/arm matching, as to lf stability.

Let's say we have a high compiance, low suspension damping cartridge. And we intentionally put it in a high mass tonearm, with no arm damping. Warpengine predicts this transient reponse :


You can see it's unstable......well pretty much so. Settle time is extended. This is poor lf stability.

Here's the same config in a 6g arm :


You can see settle time is reduced. But still isn't great ! This combination, which is commonly advised, still lacks good lf stability.

Here's the same config with some arm damping :


At last, a decent settle time and good lf stability. Note that increased damping has 'eaten' some of the VTF (cantilever force varies more with warp). But overall it looks good.

So this suggests that a high compliance, lighly damped cartridge might benefit from a bit of tonearm damping, even in a light arm. Which generally reflects experience, I would say. Also suggests running at higher VTF is a good idea in this case.

[bastlnut]

hallo,

nice spread sheets.
i said that you do good work.
you still need to include design aspects that you may not like of find of importance.
it is only fair to all if you do that.
how you calculate ratios etc. makes a large difference in the results.
you may want to calculate the stability factor of a tonearm that uses a different headshell and CW other than the original and factor that into the spreadsheet.
is the CW off axis or underslung? is the headshell higher or lower than the original?
where is the center of gravity of the tonearm? in which plane?
i will have to look at the damping calculator.
what about bearing drag?
and the affect of VTA?
suspended chassis or solid plinth?
the electrical aspects of an overstressed suspension and closer proximity to the magnets?
how about the room temp?

regards,
bas

[Ldg]

how you calculate ratios etc. makes a large difference in the results.

All parameters and ratios have classical, standard definitions. Units are always specified.

you may want to calculate the stability factor of a tonearm that uses a different headshell and CW other than the original and factor that into the spreadsheet.
is the CW off axis or underslung? is the headshell higher or lower than the original?
where is the center of gravity of the tonearm? in which plane?

ALL of those factors get wrapped up into the standard 'tonearm effective mass' definition. That's what 'tonearm effective mass' is all about, it's whole reason to be. At these low frequencies, the arm can be modelled as though it is rigid, and all the various parts of the arm contribute their inertia. It all gets wrapped up into one single entity. Tonearm effective mass is all it's necessary to know. Really !

Of course, each factor has its own contribution to effective mass. Some add, some subtract. You can use the tonearm effective mass calculator to evaluate changes.

NB this only applies to consideration of lf stability. Tonearm effective mass, the topic of this thread, is entirely concerned with lf stability. That is, the behaviour of the suspension spring/damping and the tonearm inertia. Not the vibration of the tonearm itself, whose typical lowest self-resonant frequency is far above the range at issue.

i will have to look at the damping calculator.

When matching cartridges and arms for lf stability, you can see it's crucial to consider cartridge damping. So long as you know any two of the following three you can use loafer to work out the other one. Then it will report damping for you. You need to know any two of :

compliance@static
compliance@100Hz
spec VTF range

what about bearing drag?

There are two sorts of bearing friction : stiction (bad) and friction (good). According to Leigh Phoenix, typical bearing friction comprises a damping ratio of c 0.08. If you don't know the actual value, suggest use this. My own experience is modern arms can have far smaller values, perhaps 0.04 or less. For small values like this, it can just be added to cartridge damping ratio.

One comes to realise that a little bit of bearing friction can be a good thing. If its the right type in the right place and the right amount.

and the affect of VTA?

Virtually none on lf stability. Virtually no interaction with tonearm effective mass.

suspended chassis or solid plinth?

plinth/sub-chassis resonances are vibration sources. To evaluate the effect in warpengine, change the frequency and amplitude to match the source. You'll see how much VTF gets eaten by such sources.

the electrical aspects of an overstressed suspension and closer proximity to the magnets?

in all my various tests, I've never found evidence of mechanical loading via the electrical interface. Pity, because suspension damping could then be manipulated. But no.

how about the room temp?

No idea ! Suspension elastomers probably are quite temperature sensitive as to spring/damping behaviour.

[Ldg]

Here's a screencap of the same high compliance cartridge in a medium mass arm. But with quite a bit of arm damping :



You can see, it's pretty stable. BUT quite a bit of VTF is now used to track the same warp.

Damping is key to lf stability and cartridge/arm matching. Even with a high compliance cartridge in a medium or high mass arm, it can be stable if there's enough overall damping. And there's enough VTF budget available to cope.

Cartridge suspension damping varies from cartridge to cartridge. Tends to follow 'house' rules for different manufacturers. Really lightly damped cartridges tend to have have high compliances, light VTF, and sometimes stabiliser brushes.

Common practice of matching tonearm effective mass and cartridge compliance, to aim for a resonant f near 10Hz, pretty much ignores damping completely. Which is really odd, when you think about it. And pretty crude.

I reckon if you also take both cartridge and arm damping into consideration when matching cartridges and arms for lf stability, you can get far better results than the simple 'mass and compliance' approach.

You can also obtain a far wider range of matches with application of some arm damping, or choosing carts with specific damping values. Just be careful of the available VTF range !

Personally, I think this better addresses the OP. And explains many of the real world anomalies and 'exceptions' the simple approach has in tow.

[bastlnut]

hallo,

how nice of you to quote other sources in your explanations.
have you ever seen a suspended sub-chassis move because of record warp?
obviously not because you would get very different results than your tool gives.
limiting all projections to 1st order simple LF results ignores what happens after and how it moves into the audible frequencies.
friction and stiction is placing a value on the effect of drag and this does not help in understanding its effects.
basically, too much will adversely affect performance as will too little. just right is always the best and is best accomplished by ear.

enough, i will not agree with all that you have to say and you probably none of mine because of whatever reasons you have which i suspect are self serving.
have you not heard that overdamping sucks the life out of the music, and one knows when it is overdamped because one hears it immediately.
maybe good on paper but boring as hell to listen to.

regards,
bas

[Ldg]

have you ever seen a suspended sub-chassis move because of record warp?

There are various sources of lf vibrations. You can evaluate each source frequency and amplitude range seperately, as you like. Just change the frequency and amplitude fields. LF stability is the aggregate of response to such sources.

limiting all projections to 1st order simple LF results ignores what happens after and how it moves into the audible frequencies.

No, it really is that simple. A compliance-mass-damper system. LF stability affects audio through am and fm modulation, and intermodulation distortion.

....just right is always the best and is best accomplished by ear..........overdamping sucks the life out of the music, and one knows when it is overdamped because one hears it immediately.......

Fact is that you have no other method than by ear, bas. So you don't know whether whatever you're hearing is 'overdamping' or not. And it could equally be that your taste prefers a bit of instability. It would not surprise me from some of your other preferences. It's your prerogative, and taste. That's not universal or transferable.

In practice, underdamping is always inevitable. If you ever did truly get to 'overdamped' in the classic sense, required VTF would be infeasible. Critical damping can't be the goal. It's always a compromise.

Personally, lf stability is very obviously audibly best. Unstable lf always sounds worse to me, in a whole host of guises. Based on correlating listening and measurement. And no more damping than is necessary to achieve that goal should be applied. It just wastes VTF.

By definition it's impossible for you to agree, or even credibly discuss, bas, because you don't understand what I am posting. In fact, I believe you would agree if you did. You continue to confuse very basic concepts here. Which is OK. And get agressively defensive into the bargain. Which isn't........

[flavio81]

hallo,
(...)

I've had enough.

Next time, ld, do not give your calculators away so easily. He gets them for free and then he complains that it's not able to predict everything including earthquakes, solve your taxes, make good coffee, and cure AIDS. His "what about VTA?" comment shows that either he doesn't understand a thing about it or he's just trolling.

I think it's clear that this thread is concerning arm-cartridge resonances, not stylus drag, nor turntable suspensions, nor unrelated tweaks.

[flavio81]

In practice, underdamping is always inevitable. If you ever did truly get to 'overdamped' in the classic sense, required VTF would be infeasible. Critical damping can't be the goal. It's always a compromise.

But for tuning the damping you could use a soundcard and add more damping until the point in which the resonant peak dissapears. That would be the "critical damping" point, for practical purposes.

[Ldg]

But for tuning the damping you could use a soundcard and add more damping until the point in which the resonant peak dissapears. That would be the "critical damping" point, for practical purposes.

Hi flavio81. Trouble is, anything like critical damping requires infeasible VTFs. I wonder if this may have once played a part in the old 10g VTF super heavies ? Because such tracking forces don't seem to buy much otherwise..........

As Steve posted, I would try not to let bas get to you, flavio81. Actually, there's some interesting stuff on this thread, not least of which JG's contributions, which just got swamped by the rubbish. Which I suspect could be bas' et al intention. But it's everyone's loss, really.

[bastlnut]

just goes to show you,

the brainwashing that has been done to us all forces almost everyone to only consider the scientific approach.
talk about big brother having us all in its control already.
take a risk and think outside of the box for once!
sheesh

regards,
bas