Tonearm, Cart, Headshell matching

[Barry]

What is the weight of the Micro Sieki headshell?

[RobbieGong]

What is the weight of the Micro Sieki headshell?

The original headshell is 10g. It's nice and I have it but I fancy the 16g Ortofon.

[Barry]

Try as I might (and I have spent the last hour searching the net), I cannot find a value for the effective mass of the MA-202 arm. However the MA-505 looks similar (it has the same geometry) and it has an effective mass (without headshell) of 7g. It is a significant approximation to assume a similar figure for your MA-202, since I don't know if the arm tubes are made of the same material - but it is all we can go on.

The Ortofon Cadenza Black has a mass of 10.7g and a dynamic compliance of 16.10^-6 cm/dyne (the latter figure is assumed to be valid at ~ 10Hz).

So the total effective mass as seen by the stylus/cantilever is: 10.7g (the mass of the cartridge) + 16.8g (the mass of the headshell) + 7g (the assumed effective mass of the arm) = 34.5g.

Thus the calculated low frequency of the arm/cartridge combination is:

1/(2*pi*sqrt(34.5*16.10^-6)) = 6.77Hz.

Ideally this figure should lay somewhere in the range 8 - 15Hz, so it would appear to be too low, suggesting the whole turntable/arm/cartridge could be susceptable to problems unless it is well isolated.

However this is a calculated result, and in doing the calculation I have had to make some significant approximations and assumptions.

So, (and this might seem like a bit of a cop out) I suggest you simply try it out with the heavier headshell. If you didn't have any problems with the original headshell (with which the caculated LF resonance is still a low 7.6Hz), the new combination will make little difference.

[RobbieGong]

Many thanks Barry for all your effort - very decent of you and much appreciated.

I've not had the pleasure of trying the Cadenza with any headshell yet as my deck awaits it's final upgrades.

I'll try the headshell as you suggest though as It's a very good non resonant one so hopefully it will work / sound good - can only try.

By the way - A big prize to any one who can find the effective mass of the Micro Seiki MA-202 which to date I have never found anyone who has - neither internet or forum

[kcc123]

I don't think the Micro Seiki MA202 is a heavy mass arm (like the Fidelity Research FR64) as My MA505S has an effective mass of only 14-15 grams with its original 10g. HS-202 headshell(Hi-Fi Choice No24 - reviewed by Martin Colloms). I assume if they were similar, the MA202 would have an effective mass of between 14 to 16 grams.

[RobbieGong]

If I go by this https://www.ortofon.com/support/supp...ance-frequency and assuming effective mass of 14g, then 16.8g headshell + 10.7g cartridge + headshell screws/wire = too much total mass for optimal resonance frequency range.

[phonomac]

Assuming that the effective mass is similar to the MA-505 (a reasonable assumption), the 14g includes the 10g headshell. So you need to use 4g + 16.8 + +10.7 + wires etc. That will put you just above 7Hz.

The MA-202 arm tube is slightly lighter than the MA-505 (I've held both of them in my hand )

regards

Angus

[Stryder5]

If I go by this https://www.ortofon.com/support/supp...ance-frequency and assuming effective mass of 14g, then 16.8g headshell + 10.7g cartridge + headshell screws/wire = too much total mass for optimal resonance frequency range.

I can't fault your logic or theory, probably your only course of action is to try for yourself.

[RobbieGong]

Assuming that the effective mass is similar to the MA-505 (a reasonable assumption), the 14g includes the 10g headshell. So you need to use 4g + 16.8 + +10.7 + wires etc. That will put you just above 7Hz.

The MA-202 arm tube is slightly lighter than the MA-505 (I've held both of them in my hand )

regards

Angus

And that's why you are my favourite tech Angus. You spotted that my calculation was flawed as I hadn't included the headshell weight in the 14g effective mass.
I'm liking your calculation and 7hz which would sit things in the right area of optimum range

[martian sunrise]

I've never been able to find the effective mass of the ma202 arm. I will be interested to hear your results.