I have been wanting to do this mod for three years now, but the schematics I have for my machine are terrible and hard to decipher. On a whim, I just tried to see what the poly out points defeated, since I noticed they were upstream of the highpass filter.

Luckily, they were a pure output of the combined lowpass filters.

Something tells me this mod is open to all roland gear. Even the Jupiter 6 and 8.

Every highpass filter eliminates bass, even when it is not turned up.