Hum in a phono cartridge?

So, my statement was "Balanced and isolated"
Where is the ground contact happening at the cartridge side?

I'm honestly curious, as I've not touched a turntable in decades.

erik_squires

So, my statement was "Balanced and isolated"
Where is the ground contact happening at the cartridge side?

The phono cartridge is only "balanced and isolated" if it's fed into a balanced phono preamp. But very few phono preamps are balanced. (Of those that are, not all meet the AES balanced spec, an issue Ralph frequently points out here.) 

Once a phono cartridge is connected to an unbalanced input, the cartridge is no longer "balanced and isolated."

If the phono cartridge - which as you note in inherently balanced - is connected to a truly balanced phono input, there should be no ground loop or hum problem. If there is, it suggests an issue with the cartridge itself or the pickup arm wiring that results in unbalancing the phono circuit.

@cleeds

OK ... help me out a little here. But even if it gets grounded at the phono input, that is a single ground reference. Where's' the competing ground that the phono catridge attaches to?

I'm not trying to be difficult here... I'm just genuinely not seeing the whole picture.

Of course, YES, phono cartridges are notoriously susceptible to ground loops. My own mental model just doesn't explain it yet.

When you unbalance the phono cartridge, you connect ground to neutral. The difference in electrical potential is between whatever minute voltage is on the ground and 0V, which is where the neutral should be, no?

When you unbalance the phono cartridge, you connect ground to neutral.

If you mean AC, then no.

Otherwise, are you calling ground the preamp shield conductor and neutral the catridge (-) ??