The circuit that gave rise to this configuration is from 1978. In the original publication are used other integrated circuits, but it can be mounted with 741 or LM4136, which is the low-noise version. The source must be symmetrical 6 to 12 V and input cables and signal output must be shielded. The dynamic characteristics are given by the diagram. Consumption is low and used pots are type double, or two potentiometers controlled by the same shaft. Input is for a source of low impedance signals.
