When Does A Tonearm Have Medium Effective Mass Etc

[Alec124c41]

I do things by trial and error.
I need a heavy headshell to make my MC cartridge sound better.
My stock counterweight is almost falling out the back. Extending the stub of the SME II Improved does not seem to be an option. I add weight.
I think the heavier headshell being at the long end of the arm will make more difference than adding a bit of weight to the CW and being able to use the VTF slider will take away.
I like to play with things more than numbers.

Cheers,
Alec

[Ldg]

I think the heavier headshell being at the long end of the arm will make more difference than adding a bit of weight to the CW and being able to use the VTF slider will take away.

I like to play with things more than numbers.

It's still OK to play with both .............! Look, by definition, Tonearm Effective Mass is an analytical quantity. It doesn't respond very well to intuition, unless you're wired up like Euler back in the 18th century !

It's purpose is defeated by evaluating effects of changes incorrectly. And bizarre to then wonder at the mysteries of how imperical results differ. Unfortunately there's pretty widespread misunderstanding that often contributes.

In fact, counterweight position can make a big enough difference to tonearm effective mass to take notice of. Even a few mm change. It's effect is proportional to square of distance from the pivot. Not intuitive.

And a lighter counterweight actually contributes more to effective tonearm mass than a heavy one. In balance. Again, not intuitive.

There's some dodgy advice about, unfortunately.

These are common 'errors' :

1. Underestimating effect of headshell/cartridge mass changes
2. Not taking into account VTF setting
3. Not evaluating cartridge compliance correctly
4. Getting direction of counterweight mass change effects reversed

As already posted, errors can accumulate and become significant.

I wouldn't blame anyone for avoiding the nitty gritty. It's just a means to an end after all. I'd suggest using one of the calculators. But I would fully endorse putting effort into getting lf stability sorted out.

I do things by trial and error.

Alec, you were about to try a heavier headshell and heavier counterweight together. With intent to increase total effective mass. But one increases, and one decreases effective mass. So it likely wouldn't have the desired result, and you'd never know why. And bas would invent some nonsense 'swinging dumbell' theory to 'explain' it. But the combination would never have done what you'd intended as to total effective mass in the first place !

I trust you can see the problem !

HTH !

[Alec124c41]

I just put the Denon DL-301 II, Sumiko HS-12 headshell, on the 3009. Using a gauge, with the VTF slider all the way back, I can just get a VTF of 2 grams, without the counterweight falling off.
With the modified weight, I can actually balance the arm, and use the slider. I could probably even try a 16 gram headshell.
The rear of the standard weight extends approximately 1 mm more than the rear of the modified one, but it is hanging on by maybe 2 threads, a possibly sloppy connection.
On short listening, there is very little difference in sound, with a possible edge to the modified weight, which is much more convenient to use.
Bill Evans sounds good.
I do think that a general understanding of the principles involved are important, to give an idea of which way to go in the trials. But as they say, the proof of the pudding is in the eating.

Cheers,
Alec

[Ldg]

The reason Bill Evans sounds good is because he was a phenomenal genius. That's the important bit

As to your 3009II set up, adding the heavier counterweight will have reduced effective tonearm mass. Hard to say by how much without knowing the counterweights. Not by much if they are standard SME 1901 and 1902 weights or similar, as seems possible because the location didn't move much. They're designed to accomodate different range of VTF slider weight adjustment, of course. If so, much less than 1g effective mass reduction. Not significant.

No surprise at no audible effect then.

The bigger picture is understanding why the DL-301II suits the SME3009II arm. As previously posted, there's quite a few clues that Denon cartridges have higher suspension damping than you'd think. Then compliance could be 25 to 30cu@static, 13cu@100Hz. Which would suit a 3009 with a slightly heavy headshell pretty well, from an lf stability prediction point of view.

As previously posted, common conversions of compliance@100Hz to static compliance can be a long way out.

Ether way, theory and practice converge here, and theres no mystery. But you can't expect trial and error alone, especially these specific ones, to be repeatable or transferrable in other cases. It's better to at least understand the principles involved.........!

Enjoy Bill Evans. Think I'll play Waltz for Debby now. Even Bill Evans used theory............just listen to the 1st 12 bars of Debby. Chromatic bass, alternating inversions and cycle of fifths ! It's still beautiful.

[bastlnut]

hallo,

Alec,
good to hear that you have found a setting that you like.
why not use the MMT arm for the Benz and see what that is like.

talking about dodgy advice.
ld throws numbers at everyone and still does not seem to have a grip on his theory, which is only a theory and has no experimentation to verify any of it.
any child can verify the dumbbell whip effect because it is used on more than a few toys that are played with.

i do think that making modifications to a tonearm, like increasing eff. mass with add on, does need to follow the basic design premise of the original design unless the structure of the tonearm is being changed.
the SME series III has a set up check in which the headshell is supported and the CW structure is lifted by a thread to balance the weight supported by each knife bearing seat.
there is nothing but gravity keeping the knife bearings seated and anything that reduces the stability of the gravity holding down the knife bearings will degrade the sound.
so you do not want a lot of weight far away from the pivot.

see how easy it is to figure it out without a calculator?
a heavier counterweight that is about the same distance from the pivot as the lighter CW, but with a heavier headshell will have an increased eff. mass.
it will not be lower.
don't need to be an Engineer and Duckteur to be able to figure that out.
i guess you need to be one to get it wrong though.

regards,
bas

[Ldg]

a heavier counterweight that is about the same distance from the pivot as the lighter CW, but with a heavier headshell will have an increased eff. mass.

Yes, a lower eff. mass than if the same counterweight had simply been rebalanced. So the heavier counterweight has reduced the overall eff. mass. versus rebalancing the original one. A heavier counterweight opposed an increase in effective mass from headshell then. QED. My point is proved. You're proved wrong, bas.

Look, you just don't understand it bas. I believe it's beyond your grasp, or interest, to ever do so. But advice you profer on this matter is plain dodgy then, at best. Misleading, in fact. Just add it to the list.............

The 'swinging dumbell' fantasy is your mind's invention, bas. In some mystic way it might make sense to you, but has no basis, can have no evidence. Presumably, at some level, you need to hold an explanation. That's pretty curious for such an impericist as yourself, bas. Better a wrong explanation than no explanation ?......how strange. Presumably 'dumbbell' is the psychololgical slip way of spelling it ?

[bastlnut]

.......
Look, you just don't understand it bas. I believe it's beyond your grasp, or interest, to ever do so. But advice you profer on this matter is plain dodgy then, at best. Misleading, in fact. Just add it to the list.............

The 'swinging dumbell' fantasy is your mind's invention, bas. In some mystic way it might make sense to you, but has no basis, can have no evidence. At leadt we know how the dumb got into dumbell though ........ Presumably, at some level, you need to hold an explanation. That's pretty curious for such an impericist as yourself, bas. Better a wrong explanation than no explanation ?......how strange.

what is dodgy is your reasoning.
a child knows that when the weight is further away from the pivot it takes more energy to bring it to a stop and change direction.
you ignore too much of the physics of the whole for your calculations to be accurate to real life situations.

1g less with the heavier weight closer to the pivot than the lighter one....
that may be, but you even said that you did not know the difference and the weight so your calculations are pure speculation.
then there is the vibration of the CW that is almost screwed out and hanging on by only 2 threads.
you are just referring to the theory of eff. mass
getting the set up to sound better is the goal and not the number crunching.
Alec is right of course, trial and error works better than playing with numbers.
you never try it you never know

regards,
bas

[Ldg]

.......a child knows that when the weight is further away from the pivot it takes more energy to bring it to a stop and change direction..........

We grown ups call it rotational inertia, moment of inertia. What do think effective tonearm mass is a measure of, bas ? Best go find a child to ask...........

Look, you're proved wrong. This topic is either well beyond you, bas, or it comes across as trolling again.

[Ldg]

Enjoy Bill Evans. Think I'll play Waltz for Debby now. Even Bill Evans used theory............just listen to the 1st 12 bars of Debby. Chromatic bass, alternating inversions and cycle of fifths ! It's still beautiful.

Does anyone doubt that Bill Evans applied both substantial theory and 'trial and error' in his music ?

Apols WAPFU for thread drift, but if you really want the best you have to apply both approaches.

By analogy

[bastlnut]

.......a child knows that when the weight is further away from the pivot it takes more energy to bring it to a stop and change direction..........

We grown ups call it rotational inertia, moment of inertia. What do think effective tonearm mass is a measure of, bas ? Best go find a child to ask...........

Look, you're proved wrong. This topic is either well beyond you, bas, or it comes across as trolling again.

you and your statements.
you are the one who is way off base.
reminds me of the cartoon scientist who swears that it will work and then it blows up in his face.
with a blackened face the scientist says.....back to the drawing board!
i know what it is called and i did not use the term so all can understand what i wrote.
the rotational inertia is something that you ignore among other things,
this is why i can not take you seriously and know that you are wrong and misleading in your statements.
why do all tonearm makers make a heavier CW?
becuase they want to keep the CW close to the pivot for the reason of better sound quality.
obviously something you ignore, sound quality i mean, and you unfailingly promote yourself and talk down all others.

so you see,
a child does know better than you because a child does not have tunnel vision.
a child also tries things to see if they like it and keep what is good.
all what you do not do.

personal experience and experimentation.
what you do not have and do not try.
i bet you could be a great help, but you refuse to try anything or, it seems, to think logically for that matter.

i would not send a tonearm for you to test because you will only create computer projections based on some limited factors like weight and size.
my Engineer friends take measurements and conduct experiments.
these Engineers i trust.

regards,
bas

[Ldg]

Best relax, bas. Posting like you're coming apart at the seams.....

.........the rotational inertia is something that you ignore among other things....

Well, that's obviously more nonsense, bas. Rotational inertia and tonearm effective mass are one and the same thing.........

Look, in my mind your reputation has a junk rating anyway. But all you're doing here is justifying that, and proving it to all. If it ever needed proving......

Beyond that, your posts distract from useful and helpful content on this thread, bas. Sort yourself out.

Go listen to some Bill Evans, hear what happens when you combine soild theory with 'trial and error'

[Ldg]

Go listen to some Bill Evans, hear what happens when you combine soild theory with 'trial and error'

At risk of labouring the point, but I mean hear what happens when he (Bill Evans) combines solid theory with 'trial and error'. Not bas, obviously ! ...........In case you couldn't tell

[mattlynch]

hello gents,
so after all your banter could someone just clarify something,
if a user wanted to use a denon DL103 on a rega rb 300 but wasn't getting satisfactory bass should he add mass at the head shell and counterweight?
cheers,
Matt

[Ldg]

......should he add mass at the head shell and counterweight?