Adding a 'middle' tone pot

[Roobin]

I was thinking about 3-tone stacks. I know about high and lowpass filters. However, what i don't understand is how you can make a filter for a particular frequency. Perhaps you could combine two filters (high and low pass) centred around the freq. in question, but there mut be an easier way than this.

Any help appreciated.

[Mark Hammer]

Look at the article on "simple easy parametric EQ" at Geofex.  It's all explained there with some working examples. http://www.geofex.com/Article_Folders/EQs/paramet.htm