I need a headshell recommendation for Technics 1200 GAE

@invictus005 

Here is detailed explanation of what is Effective Mass, someone posted all that before, i will just quote again: 

"So effective mass in not mass - it's inertia! In fact, even the common measurement (in metric grams) is a misconception. This is brought to you here, by the tonearm manufacturers, as a curtsy to the layman. Effective mass, like any inertia, is measured in Kg/m/s2 (that is kilograms per meter per second squared). Since we're talking very small mass here - everything is divided by 1000 and so we're actually dealing with grams per millimeters per second squared. The general em formula relationships are manipulated such that we're left with grams only - but nevertheless it's Inertia!!!. Keeping that in mind it's easier to regard effective mass for what it is.

Another misconception is the relationship between 'effective mass' and mass. If you add 1 gram to the tip of the tonearm you do not add 1 gram of effective mass to the tonearm No way Jose!. You do not add a 1/3 or a half - none of it catches here. So, how much do you add? Well, that cannot be described in English, it can only be described in a math equation. This is what it looks like:

M(kg) = m(r²/L²) + (Z/3)

m is the counter weight mass
r is the counter weight distance from the pivot
L is the effective length (pivot to stylus tip)
Z is equal to twice the mass of the front end of the tonearm at the effective length. Your headshell mass is part of 'Z'.

M is the effective mass and the whole thing is in kilograms but it doesn't matter. This is just to demonstrate why the relationship between mass and effective mass is not as straight forward as one might think.

L (the leverage or effective length) will affect the importance of the real estate the most. In other words - the tip of the tonearm is the most strategic location where masscan affect inertia. Adding just a tiny amount of mass to that specific location might, just as well, be equivalent to the total effect the counterweight has on the effectivemass of the tonearm. It's that important! This is where 'r' vs 'm' in the formula kicks in.

Having said that... movements of the counter weight back and forth across the back of the tonearm seldom changes effective mass by any significant amount. It's typically punched in and pre-calculated into the specs of the tonearm and it's a generic part of the given effective mass."

Dear @chakster : Of course is part of inertia ( inertia's moment. ) and that's why where we can have the higher changes on that total effective mass/inertia is precisely at the headshell position.

You have to understand that the deep/whole inertia concept/matghematics could be complex to for we " mere mortals " calculate it through tghose mathematics because you have to think that the mass of the  headshell and cartridge is not " seated "/concentrated at only one point but the cartridge and headshell overall body, along that body shape, each mm. is at different distance from the center of the tonearm pivot ! !

That's why things, even that are not absolutely correct, were made more simple for audiophiles and it's what @invictus and every one takes as " true ".

Yes our calculations on that cartridge/tonearm frequency resonance range is out of absolute reality but never mind and follow what we have on hand and be happy with.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

@chakster I understand what effective mass is and the required calculations. What I wrote earlier is correct. 

I have the Audio-Technica ART 9 so finding a low mass headshell may be a priority.  I'm following what invicuts005 is saying and I don't see how he/she is wrong--but maybe I'm missing something.  

If I’m reading the equation correctly, Z is an independent term that is simply added to the calculation after being divided by three. Since you’re only concerned with the delta here, calculating the change in effective mass is (I think) pretty straightforward. Whatever total Z is, the only part of it that changes with the headshell swap is the difference in mass of the shell plus screws, wires, etc (call it the shell package).

If the original headshell was (let’s say) 7.5 grams and the replacement package is 16.5 grams, you’ve increased effective mass by 3 (16.5 - 7.5 =9 and 9/3 = 3 grams) since that’s the unit of measure here.

The change in counterweight position and effective length should be very close to zero.  If you sub in a heavier counterweight and don't move the cartridge, it will be zero.

Yes?