This is the page for the little grungy black ranger.
The Manual for the Ranger SS-1: ss-1.pdf
The Ranger: 
Noise
To calculate the fundamental noise limit of the GS-13, we need to add its intrinsic thermal noise with the noise of the readout electronics.
Brian Lantz went through this exercise for the GS-13 seismometer: GS13readout.pdf
The SS-1 is a similar instrument, but with the following different parameters:
R = L = G = M =