This circuit was found in a Popular Electronics from the 90's. The frequencies depend on the components indicated in the table next to the diagram.
This Baqxandall tone control can be used with any low Power audio stage as the input of a audio...
This circuit can be seen in several publications of the same time. The circuit is an application note...
The power supply for this circuit found in a QST magazine is given in the previous circuit. The...