My BBD effects sound obviously distorted as well. I’ve built guitar pedals and with analog delays you have to bias each bbd chip to the middle of its operating range with a trimpot and an oscilloscope. I didn’t see a bunch of trim pots in the pictures on gearslutz of the circuit boards, on the board with all of the bbd chips. I’m not sure how they do the biasing. It is possible everything is biased to the middle of its range, but the bbd is simply being overdriven? That’s the best you can do with bbd chips, is just bias them to the middle of their range, so if they clip, it is symmetrical. The way to tell if the biasing is right is to look on an oscilloscope or zoomed to a recording of a daw, to a recording of a 100% wet triangle wave, force it to overdrive the bbd (but not the filter!) and see if the clipping is even on the top and bottom of the wave.