Im having problems with a Micromoog.
In short its low output and NO bass at all as well as the VCA creating a popping sound when set to fast attack.
But I have checked the synth thoroughly and all functions seem to work properly except for the mentioned problems.
Same Hipass result when running Pink noise into the audio input and the cutoff seems to start at around 600hz and severely cuts off at about 200hz resulting in NO low end whatsoever.
In fact when i turn down the cutoff the signal pretty much disappears.
I noticed in the service manual that the filter seems to be split into two sections.
Filter HI end ( 700hz to 1400 hz) and Filter Lo end (44hz to 176 hz ).
There could be a problem with the Filter Lo end section , it has a couple of LM 3046n Ic´s that i have tried replacing without any change.
So far i have tried changing a few caps as well as the output opamp but no luck.