Thank you both for the advice. I have looked up the MK´s BSC filter and i´m comfortable building this. Can i copy the hole filter at MK´s website or do i have to change the values on the parts?. I dont have much knowledge about this kind of filter and my books doesn´t get into it, so i feel a bit lost here. Is the BSC filter doing the same as the notch only boosting the lows instead of toning down the highs? I would be very happy for a suggestion on the circuit values if i can´t copy the Martin Kings consept!!!! I will soon post some pictures of the Jerikos and some comments of the building and the changes i did to it. Thanx!