ZYX Compilance

@dolphytrane forget about static compliance, only dynamic compliance is what we need to choose the arm. Vinyl engine is a source with a lot of misinformation when it comes to data. ZYX dynamic compliance is 15cu (horizontal) and 12cu (vertical), both measured at 100Hz.

To convert it to 10Hz we have to multiply on 1.7 (not on 2.2).
So everything you have written is wrong. Where did you get your data, do you have ZYX cartridge ? I have original manual on hands from my ex ZYX Premium 4D SB. Static compliance does not even mentioned in the original printed manual for ZYX (because nobody need it).

at 10Hz ZYX compliance is about: 
25.5 cu (lateral)
20.4 cu (vertical)

This is medium dynamic compliance and it’s quite normal for a modern LOMC. This is the reason why ZYX is fine for most of the modern tonearms.

@chakster
I do have a Zyx cartridge & in my manual it simply says 'Compliance' it does not state whether it is Dynamic or Static or what it is measured at either 10hz or 100hz, hence the reason for starting this topic.
If the compliance is how you have calculated at 25.5cu & using your ETA arm, according to the manual its effective mass is 22g with a 6.5g cartridge, I don't know the weight of your 4D but my cartridge weight with SB is 7.9 so this would increase the mass with the ETA to 23.4g using the calculation in the article link by rdk777 we get an RF of 6.5 it is also stated in this article that the desired range is 9-11 so your combination is well outside the range.
rdk777 states' I'm currently using the ZYX Universe II Silver base (8.2 gm) w/ the Kuzma 4P (effective mass - 13 gm)' if we use these figures to calculate RF we get 6.8 another combination that works well according to rdk777 but is well outside the range.
If your cartridge is working well in your ETA image how much better it would be in a low mass arm. If we aim for an RF of 10 right in the middle of the desired range using your calculation of 25.5 compliance & my cartridge weight of 7.9g I would need an arm with effective mass of 2.1g.I would really appreciate your recommendations of an arm in this range.

I agree - seems like the calcs aren't coming up with the right values or ones that make sense.  I've attached a link to a thread where GT Audio (I believe is the UK Rep for ZYX) says that ZYX recommends tonearms with effective mass of 12-20 gms - which puts it in the medium mass tonearm range.

https://pinkfishmedia.net/forum/threads/zyx-compliance-10hz-or-100hz.195170/

Thanks, quote as stated by GT Audio

EQ Compliance horizontal - 15×10-6cm/dyne
EQ Compliance vertical - 12×10-6cm/dyne

Recommended tonearm effective mass 12grams minimum/20grams maximum

With the TB or SB headshell added it will be:

+TB - recommended tonearm effective mass 9.5grams minimum/17.5grams maximum
+SB - recommended tonearm effective mass 7grams minimum/16.5grams maximum.

Therefore a tonearm with a medium effective mass is recommended for all of the above.

Could someone with a Zyx cartridge and a test record please send in their results. This seems like the only way to get a definitive answer.

I do have a Zyx cartridge & in my manual it simply says ’Compliance’ it does not state whether it is Dynamic or Static or what it is measured at either 10hz or 100hz, hence the reason for starting this topic.
If the compliance is how you have calculated at 25.5cu & using your ETA arm, according to the manual its effective mass is 22g with a 6.5g cartridge, I don’t know the weight of your 4D but my cartridge weight with SB is 7.9 so this would increase the mass with the ETA to 23.4g using the calculation in the article link by rdk777 we get an RF of 6.5 it is also stated in this article that the desired range is 9-11 so your combination is well outside the range.

My EPA-100 (not ETA) has been in use with ZYX Airy III without Silver Base, don’t forget that EPA tonearm has a very special counterweight mechanism to deal with cartridges with different compliance, you can read in Technics EPA-100 manual, this is unique option, no other tonearm will give you something like this. 

If we aim for an RF of 10 right in the middle of the desired range using your calculation of 25.5 compliance & my cartridge weight of 7.9g I would need an arm with effective mass of 21g. I would really appreciate your recommendations of an arm in this range.

Reed 3P "12 Cocobolo was my second arm when i upgraded from ZYX Airy III to ZYX Premium 4D Silver Base (7.9g) , the effective mass of my Reed tonearm was 18-19g (without cartridge). Reed is an excellent toneam for any cartridges, you can buy Reed in 9.5, 10 or 12 inch length and each wood has different mass, so you can buy what you need. Absolutely amazing tonearm with so many unique features. 

P.S. You don’t have to worry that much to keep your arm/cart resonance at 10Hz, this is theory, practically you will not hear the difference anyway, just try to stay in the range of 8Hz - 15Hz.