Geophone band extension

#1

Hi to all, I was taking a look to documentation about range (frequency) extension of geophones.
I’ve understood I can do this using negative impedance converter (NIC) and low-pass active amplifier.
Taking a look to old datasheets (such Lennartz) it’s reported optimal negative impedance value is 0.8 geophone coil resistance.
Increasing impedance value (e.g. 0.9) I can furtherly increase geophone bandwidth, so which are disadvantages to increase damping factor?
Thanks.

#2

Hi Elberto,

Branden is out this week but will send you a reply when he’s back in a few days.

Ian