Originally Posted by Technotitclan
The frequency is also set internally for the mid but Bart provides info on how to change it by adding capacitors to one of the connections on the mid pot. I figured if it can be done with the mid maybe it can be done with the bass.
I'm more than happy experimenting with it but I'd like someones recommendation on what cap value to start with to add about 10hz.
I can put the whole schematic in a Spice model and give you a definitive answer, but it may take me a few days to get around to it. Just eyeballing it, you could try adding a cap in the 1uF-10uF range between the green lead and the 25K volume pot. This will roll off the low-lows and move the effective bass center/corner frequency up a bit. The smaller the cap value, the more rolloff. It'll also have some effect on available boost and cut and overall frequency response (less boost, more cut, less low bass at "flat" detent), which you may or may not like.
Using something like fdeck's high pass filter would give you variable control, and a steeper rolloff if desired.