SME V arm: dynamic VTF or straight weight

Hi DerTonarm,

cart compliance is a major input parameter in the calculation of arm / cart resonance, yes?

So, I'm trying to figure were we are regards the maths part of it.
Unless you are saying, a medium mass arm with a higher weight cart becomes a (sort of) higher mass arm. If that is so, then we are actually making things better, considering a medium compliance (12 ~ 16CU), or?

If, as you suggest the cart is heavy (stone body etc.) and the compliance is high (24 ~ 36CU) than the maths should again show, that resonance is out of the acceptable band as mentioned earlier (7.5Hz ~ 12Hz). Or do we have here the first case were the maths/facts do not tell the full story?

Interesting is, to my current understanding and assuming a 'reasonable' cart weight (5.5 ~ 8.5g), a high compliance cart with a light-mass arm, such as was the rave was in the 80s for a while, actually creates lesser IGD issues, YMMV.

There are of course other factors why compliance 'generally' has moved back from that dizzy height (very soft) of e.g. 36CU, to something in between to the other extreme, the VERY stiff (low compliance SPU, DECCA, EMT, etc.) of the 60s.

Now, will the maths tell it, or not?
If not, we all would be relinquished to try lots of different arms, or as I also said, not be able to listen to some marvellous carts.
Makes you think, doesn't it?

Greetings,
Axel

Well said, Daniel. As some have said on this forum, the arm and the cartridge and their 'marriage' are often more important than the platform they sit on.

Hi Axel, well - usually I did not get very sympathic comments here whenever I refered to math/geometry in analog playback set-up.

Maths would tell the story here too, but I will put it in more general words:

- the heavy cartridge body does add to the effective mass of the moving system (tonearm + cartridge + generator - NOT stylus) in a very special way. The body mass of a heavy cartridge can - and will - alter the effective moving mass extremely. Thats why the "regular" calculations (middle-mass tonearm + medium to high compliance cartridge ) are all a sudden null and void. One of the reasons why so many audiophiles aren't thrilled with the sonic performance of the high-priced (and heavy....) stone-bodied Koetsu's.
These cartridges are almost impossible to mate well with ANY tonearm.

High compliance - low compliance - medium compliance - these are are results of special requirements in the design of a given cartridge. This has to do with interaction between magnetic force, suspension material, cantilever stiffness, moving mass of cantilever/stylus and several other factors.

Jonathan Carr could write you a 2 pages post about these.

Coming back to this topic here, - and to concentrate the output.... - the cartridge bodies weight has such a big influence (if of considerable mass) on the behaviour of the tonearm and on its effective moving mass, that it can make it impossible to mate a particular cartridge with ANY tonearm.

A stone-bodied Koetsu will perform well in a very few tonearms. In these tonearm it does so, because these arms do feature outstanding energy transfer abilities and are extreme stiff and rigid. But even in these tonearms it is still a missmatch because the combination of high compliance PLUS high body mass is a NO GO for any tonearm. (God, - the Koetsu-lovers will kill me..... hey there! I like Koetsu's too, but would always go for the RSP....).

IGD - has nothing to do with compliance or mass alone.

Usually you are better off, if your cartridge is a good "tracker".
IGD can most likely be avoided, if your alignment goes for the 2 zero widely spread and the 2nd close to the run-out grooves.
IGD is a question of geometry and trackability. Many high compliance MMs do feature extreme trackability - but this alone does not mean low IGD.
Align a Shure V15VMR with IEC-geometry and play a DECCA SXL with Ravel Daphnis & Chloe conducted by Monteux:

You will get IGD even with the 100µm+ trackability of the Shure.
Because your Shure's stylus will already be close to its maximum error with the big crecsendi on the sides end.

An ultra hard 5-6 compliance FR-7 will easily go through those inner grooves without any distortion if mounted in a FR-60-series and aligned with a Denessen tractor.

Greetings,
Daniel

Hi Daniel,
let me get used to this now --- and welcome once again "In der Loewengrube"

>>> A stone-bodied Koetsu <<<
Yes, I hope you'll survive that one. I get your point, and if only for one reason: the other end of that spectrum the DL-103 i.e. a light body with a very low compliance.
This will need some heavy mass arm, end of story.
But now go to the resonance calculation it will confirm this (I bloody well hope so!)
Daniel do us a favour, go check: http://www.resfreq.com/resonancecalculator.html
and let us know if you're findings will be different. And if so - why?

>>> Usually you are better off, if your cartridge is a good "tracker". <<<
Well, right on the money I say --- BUT trackability was the very reason why folks like vdH went to the extreme of 36CU, right? And the Shure V15's (I owned one ages ago) also. Yet again a BUT, the problem I recall was, the EXTREMLY low VTF used in order not to bottom it out in the first place!

Now lets look at some of the low compliance carts. There is not a single ONE, that can claim better than 60µm, yes? Which is a pretty poor showing --- just looking at the maths :-)
Now one more BUT, they also use humongous VTF! 4g and more! If that needle (almost all had a round type, conical stylus then) dropped on the vinyl it made some sizeable pit mark. So it didn't track too badly because it used VTF like a ton of bricks.

So let’s have your take on that resonance-calculator's findings please. And we'll watch out for those lions not get us chewed up over Koetsu and Denon...

Greetings,
Axel

Hi Axel,

the resonance calculator is fine and will work fine AS LONG AS IT DOES NOT DEAL with cartridges of extra heavy weight and/or on tonearms with extra long (10 - 12" ) effective length.

Why?

Because the extra heavy body is on the extreme end of the lever and therefor its add up to effective MOVING mass is very high. To calculate this you need more than just that 3-way calculator - you would need the effective length of the tonearm too and the added mass of the cartridge taken into account in relation to its distance to the pivot/bearing point.

As for the trackability of low compliance cartridges.
Most better samples SPU's and almost all FR-7-series cartridges I have heard (about 4 dozens so far) do easily reach the 70 µm and beyond if aligned and balanced perfectly in a well-matched tonearm. The FR-7-series performs usually around 2.5 to 2.7 grams VTF. EMTs the same. The SPUs do range from anywhere between 2.5 the lowest and up to 5 for some of the older style samples.

VTF alone doesn't tell you any story about trackability. High compliance can not go with high VTF - for obvious reasons. But low compliance doesn't nessecarily needs extra high VTF either.
So your general assumptions on the trackability of low compliance carts is wrong.
However - most if not all high ultra-compliance carts are MMs. They are - viewed as a group - better "trackers" than the MC anyway. But for different reasons than compliance.

So - the calculator mentioned is fine, as long as you deal with moderate weight cartridges in 9" tonearms. When the total length and/or the cartridge mass do increase considerably, it is a different story and the calculation is enhanced by a VERY dynamic factor. Thats why all these calculations fail as soon as you deal with say a Koetsu Onyx or similar.

The crux is the added mass so far away from the bearing point and its immense effect on the effective (NOT static !!) moving mass.

Hope this helps to clarify the point.

Cheers,
Daniel