Pani ... New ART-9 up and running ...

For my set up to hit the sweet spot, what weight cartridge would accomplish this?

The change in cartridge weight won’t impact it as much as the tonearm mass and cartridge compliance. Honestly this combo puts you right in the low end of the sweet spot to slightly below (7-8hz cartridge resonance). You can run some numbers on vinyl engine.

https://www.vinylengine.com/cartridge_resonance_evaluator.php?eff_mass=10&submit=Submit

Along the left you’ll see cartridge compliance. AT rates the ART9 at 18×10-6cm/dyne (100Hz). Assume 18×10-6cm/dyne (10Hz).

I’d be shocked if you weren’t pleased with the setup. You get into that orange area and you’d start seeing issues.

I had some concerns initially and even considered some nylon or aluminum hardware I found online somewhere which might’ve save .5 grams on cartridge weight.  But I never saw any gremlins pop up so I didn’t bother. You’d be hard pressed to find a cartridge in the sub $1000 category that didn’t have multiple shortfalls compared to the ART9.

I’m rambling now. FWIW you’re better on the low end. The higher resonance value will cause a much bigger issue when it falls in the area of the frequency of the music being played. The lower end resonance value becomes an issue with warped records as the cartridge is playing rumble from the bouncing up and down. With a good center weight most people wouldn’t ever know they have a low end resonance issue. If you have a outer periphery ring weight you’d be even better yet. I just have a center clamp (screw down type) and I don’t have a lot of warped records. No issues here.

Here is some lightweight headshell hardware.  

https://www.amazon.com/FYL-Turntable-Headshell-Mounting-Hardware/dp/B01J5FAGQS#featureBulletsAndDeta...

Thanks Wrxified for the information... the nylon hardware certainly looks interesting.   However I am not sure I'd need it if I am reading the chart correctly.  On the left side where it reads 18 for the spec you supplied on the ART9, it lands at 9hz if I come across to 8 to 9 grams which would be the cartridge and some minimal mass from the screws.  That is squarely in the green.   That is if I am reading this chart correctly.   

Sorry I typed that wrong. I’m on my mobile. Meant the following but I’m going to add some data. Also keep in mind the compliance rating on the left side of the vinyl engine chart is based on a 10Hz compliance measurement.

AT rates the dynamic compliance on ART9 at 18×10-6cm/dyne (100Hz), most people would say that the 10Hz dynamic rating would be about 1.5 - 2x the 100Hz measurement.

This would put the 10Hz dynamic compliance measurement at 27- to 36x10-6cm/dyne (10Hz). That is an extremely high compliance cartridge!!! Why Japanese cart manufacturers rate at 100Hz is mind boggling to most people. The problem is there is no direct calculation from 10Hz to 100Hz.

I’ve read other people who say you can take the static compliance of a cartridge, which for the ART-9 is 35×10-6cm/dyne, and divide by 2. Again no direct correlation and it’s only offered as a guide. But if we take the 2nd method, you end up with a much more medium high compliance cartridge which seems to jive with what others are seeing.

On the Hoffman forum ART-9 thread there are are countless members with tonearms in the 10-12 gram range that have the cartridge running. Some describe the cartridge experience as if the moment they mounted the ART-9, the clouds above them opened and angels started singing down upon their audio system. 😂. Several of them also ran the combo through various test records to measure the resonance, and came back with a combined resonant frequency well within the 8-11hz range.

This would lead me to believe the cartridge is a moderately high compliance cartridge, not the extremely high end one that many systems would struggle with.