Why don't Rhodes pickups buzz like guitar single coil pickups?

[orangefizz]

I've been experimenting with a little single coil guitar pickup on various strings/tines and reading up on how to shield one against hum. Being new to pickups I didn't expect quite so much buzz (the web is full of how-to guides to shield the pickups...not sure if they're all that effective) but I've not seen similar complaints about Rhodes pickups. Aren't these also single coil pickups? How does it not produce 73 times the amount of hum/buzz?

I also poked around on here looking at whether anyone tried humbucker-style pickups in a Rhodes/Wurli. I'm curious if/how that affected the sound (I'd imagine it would affect the higher registers more).

[The Real MC]

Answer: Impedance.

The higher the impedance, the more sensitive pickups are to interference and hum.

Guitar pickups are high impedance.  Rhodes pickups are much lower impedance.

Rhodes pickups aren't completely impervious to interference - if you stack anything with a power transformer on top of a Rhodes, the pickups WILL hum.

Rhodes pickups are sensitive to loading.  "Loading" meaning the input impedance of the preamp or amp it is plugged into.  The pickups on my Rhodes were very noisy when I tried to take the signal directly off the harp.  If the input impedance is too low on the preamp or amp, the loading causes noise and the piano tone sucks.  But when I tried a Countryman type 10 DI with input impedance of 10Mohms, the noise stopped and I got a great sound from the piano.

[orangefizz]

Thanks, very informative!