[Takahashi, Mitsuhashi]

The spare pre-amp boards provided by Nikhef are limited. It is necessary to make new boards by ourselves. We tested a prototype board (photo) using the spare geophone pod and the geophone distributor. The plot shows the spectra of the new pre-amp outputs compared with the Nikhef pre-amp. The pod was put on the ground horizontally. To fix the proof mass, the pod was stood up vertically. The prototype board had the noise floor higher than the Nikhef one by one order at 1Hz.