I have joined in the ZYX Family

This cartridge is addicting. 

Racedoc, I'm probably only 1/2 gr from the 25 now. Thanks for the info.

I’m the renegate of ZYX, my last one was copper coil Premium 4D with SB2 paired with ZYX headamp.

Do you guys are aware that after 2000 hrs you will have to invest 60% more to replace your ZYX (with worn out needle) to the new one officially? Since the original 4D is no longer available you will have to invest even more to upgrade to the newest models which are always more expensive. It’s like paying at least $2500 each time when you reached 2000 hrs of playback with ZYX’s Micro Ridge stylus tip. I think it’s extremely expensive service, are you sure you get more complacency when you pay more? Addicted?

Mehran is a very nice guy, i was always looking for Miyajima cartridges he’s offering along with ZYX. But the official Miyajima service is much more reasonable in Japan, not so expensive.

Chakster. I hear you. Two things I'll point out. There are more ways to replace Zyx than through Mehran I bought mine used (200 hrs) at a ridiculous low price. The owner, another audiophile, bought a Universe at a great price and only had this mounted for 4 months. Then, there in Mr Juki. I'm aware that Zyx has changed from the early days where their cartridges were reasonably priced. I'm also aware that 2k hrs is a lot of hrs.

IE, I kept a close  count on my Benz cart (bought new) by tracking the number of album sides. I figure 20 minutes per side avg. I bought the cartridge in 08 or 09 (I believe) I just counted up the hrs on that cartridge. It was 325-350 hrs. 350 is adding 25 for overage.  I did take a 3 yr hiatus. But I was surprised that the number was so low. But it was. Even if I added 20% (25 minutes per side) to that number, I am only at 425. Thats a long way from 2000. So I'm not concerned

Juki sells gray market products with fake serial numbers, i do not trust seller who manipulate with serial numbers. My first ZYX was purchaced from him, second from Mehran.

ZYX refurbished by well known re-tippers are no longer ZYX cartridges! The cartridge body is sealed as far as i know, the cantilever looks way different from any other manufacturers, the way the diamond is mounted also looks quite unique. Someone can glue the new tip, but this method is different from the original method. Nakatsuka San simply exchange the old broken or worn cartridge to completely new cartridge, he does not touch the old broken or worn carts to fix, because it’s too complicated. Nakatsuka-San will never do that with a cartridge with fake serial number from the gray market, carts must be purchaced from the distributor (and can be upgraded to the next model). The owner of ZYX can do nothing better than follow these rules to keep the sound of ZYX if the stylus is worn (every 2000 hrs max). Buyin’ used ZYX with unknown hrs of use is even more risky to end up like that sooner or later. So this truly High-End cartridge is very expensive for everyday use, especially for those who would like to stay with this ZYX sounds forever. It’s a kabbalah, each time the owner of ZYX must pay more to upgrade to the next model, this is how it works. Let’s just face it.

I’m no more user of ZYX premium cartridges, but i do not regret it.
This cartridge is not for everyone, they are good, but practically those premium models are for reach guys and the prices go up every year with the new models, now they call them the ultimate. 

Chakster, 2000 hours is a long time. Even if you do pay $2500 for a re-tip after 2000 hours, think of it as about a dollar per hour of enjoyment.  That's cheap fun, compared to theater, movies, live music performances.  My ZYX UNI has about 40 hours on it now, so I have a long way to go.  I don't know what other similarly excellent MC cartridge would cost much less to use, if you assume you will eventually get a factory re-tip.

I don't know how racedoc figures 25g as being ideal, but if it is, then there is plenty of leeway up or down from that number where the resonant frequency would not be appreciably affected. The math tells us this.

At the risk of being pedantic, which this is, the effective mass of the moving parts is equal to the net effective mass of the tonearm, headshell, screws, and cartridge, plus the effect of the counter-weight on the net effective mass, taken together.  The math for that is tricky (I know that I don't know how to solve it, anyway), so most of the time we are just approximating a value based on the given effective mass of the tonearm, if the manufacturer is kind enough to give us that piece of information.