Vintage Synth Repair

Hi all
As declared inthe files section there is a new image of the outputs 
from the Yamaha CS80 (same on other CS poly synths); leave the Vactrol 
for a moment: just would like to know if these are lowpass shelving 
filters, as they are used by the pedal to control the volume,or instead 
they are common lowpass filter: could anybody tell me if are they two 
pole filters?
Thx for any help!
Max